Recoil effects on Accuracy

[Ray B]

I thought the lead sled was hard on scopes with the shock wave and sudden stop??

Most scopes are designed to withstand the acceleration of recoil but not the deceleration of the jerk to a halt caused by the lead sled. If the lead sled were fitted so tightly to the rifle that the rifle couldn't move without carrying the lead sled along with it, recoil wouldn't be a problem. Unfortunately for the scope, there is enough slack in the connection between the rifle and sled to allow for the short burst of recoil, then the stop- which is what I understand is the source of damage to the scope.

 

[samu]

The biggest influence on accuracy, in my view, is recoil shyness, i.e. the flinch

Started didn't want to discuss this but you're right. Mause M98 lock time is 4-5ms, barrel time of bullet is about 1.5ms. Movement due recoil does matter but lot more can happen before the bullet even starts to move.

 

[Ray B]

The biggest influence on accuracy, in my view, is recoil shyness, i.e. the flinch

If the shooter is consistent enough in his/her shooting technique, the error can be diagnosed by the pattern. the common errors are flinching, jerking, bucking, body alignment and "chasing the bullseye". For a right handed shooter flinching (pushing the rifle away from the face) will result in a 2 o'clock pattern, jerking the trigger= 4 o'clock, bucking (pushing forward with the shoulder in anticipation of recoil)= 7 o'clock; body alignment which causes the shooter to hold the rifle on target using muscles will result in a pattern in the opposite direction of the muscle efforts; and chasing the bullseye (primarily with iron sights, changing the focus of the eye from the front sight to looking at the target as the rifle is being fired, will also result in a pattern that may resemble a shotgun.

 

[One Day...]

The physics of it...

Your opening post is fundamentally correct Ray B.

In simple terms the moment the powder charge is ignited two actions start simultaneously: in one direction the bullet starts traveling through the barrel, and in the opposite direction the rifle starts recoiling. This is just physics.

Of course the bullet takes a very small time to travel down the barrel, but during this time the rifle does move, and how the rifle moves and where the barrel points as the bullet leaves the barrel determines where the bullet will hit. Again, simple physics.

Recoil per se has no intrinsic effect on accuracy, but recoil control, and recoil control consistency are critical to accuracy.

This is the reason why shooters looking for ultimate accuracy (from 50 meters .22 LR 3 Positions Olympic Match, or prone English Match shooters, to 1,000 yards Palma Match shooters, to military or law enforcement snipers, etc.) will never shoot a rifle that they have no sighted themselves, because the variables in human nature, shooting form and recoil control techniques are such that no two shooters control recoil the same way.

This is the reason why British double rifles makers in the golden age asked their clients to come and shoot the rifle during the regulation process, because they realized that a critical variable in the double regulation is the control of the recoil and the yaw. The same .470 double rifle will assuredly shoots to different points of impact, and likely produce different group sizes, with 120 lbs Jack who rolls with the recoil and 230 lbs John who fights the recoil.

Of course, the effects are magnified with high-recoil rifles, but the principles also apply all the way down to .22 LR rifles. I shot pre-Olympic for about 5 years with an Anschutz 1913 Super Match 54 rifle that weighed 11+ lbs, and it is hard to believe that shooting something like that, prone, with competition sling, compression jacket, etc. still comes down to consistency in recoil control. With an 11+ lbs .22 LR rifle shooting low speed match ammo, for crying out loud, one would think that there is no recoil to control, right? Wrong...

Now get to .458 Lott or darn anything in between, and you get the implication: the biggest factor in shooting accuracy is recoil control and consistency in recoil control. The faster and bigger the recoil, the more difficult...

Beside the obvious: the caliber and load (specifically: bullet weight, powder weight, burn rate, and barrel timing, i.e. the time the bullet takes to exit the barrel), the factors at play include virtually anything you can think of: rifle weight, stock design, stock fit, recoil pad characteristics, shooter position, rifle support, shooter mass, shooting form, shooter clothes, etc. For example, a rifle will change point of impact (POI) subtly (or no so subtly) if you as much as change the recoil pad on it... It may not show much difference between a 3/4" and a 1" Decelerator, but experiment adding a slip-on absorbing recoil pad on a military rifle that has a steel butt plate and you will be surprised at the outcome...

So, the reality is that shooting with or without a lead sled does produce a shift of POI, not by feet mind you, but by an inch or two typically, because the recoil control dynamics change, even if we do not typically see it when shooting at game where, truth be told, we do not measure POI vs. point of aim as long as the bullet lands somewhere within a few inches of where it was intended and kills cleanly, but if you want to verify the lead sled effect, there is nothing simpler. Shoot 5 rounds with the sled, then 5 rounds without the sled, you will see a shift of POI, it may be big or small, depending on your technique, but it will be there, it is simply the physics of the application of forces.

I will be the first to say that as long as the shift of POI does not exceed 1" or 2", who cares !!! Heck the wobbling of the rifle on the sticks or in field shooting positions, sitting, kneeling, or, God forbid!, standing off hand, will create a lot more variation in the POI that the use or not of the sled, but you will never see a sniper or competitor use a sled to sight their rifle...

In the end, this is why some calibers (especially those that recoil fast and furious) have gained the reputation of being "difficult to shoot well." Of course there is nothing difficult in aiming them or pulling their trigger, and nothing inherently wrong with their ballistics, but keeping them pointed in the right direction under fierce recoil is difficult, especially when the recoil is fast - hence when the bullet still has a substantial portion of barrel to go through while the rifle moves a lot, and doing it consistently always the same way is even more difficult...

Changing the characteristics of the rifle (adding or removing muzzle brakes or suppressors, etc.) obviously change the dynamics of the recoil, hence the POI.

Then we can add the next layer to the discussion, which includes all the types of shooter errors (general category: flinch) caused by recoil that either scares or hurts, or both...

Some appear to be impervious to recoil but most of us are not, and this is why most of us, myself certainly included, shoot a .223 a lot better than a .458

 

[Uwe Jaspersen]

The physics of it...

Your opening post is fundamentally correct Ray B.

In simple terms the moment the powder charge is ignited two actions start simultaneously: in one direction the bullet starts traveling through the barrel, and in the opposite direction the rifle starts recoiling. This is just physics.

Of course the bullet takes a very small time to travel down the barrel, but during this time the rifle does move, and how the rifle moves and where the barrel points as the bullet leaves the barrel determines where the bullet will hit. Again, simple physics.

Recoil per se has no intrinsic effect on accuracy, but recoil control, and recoil control consistency are critical to accuracy.

This is the reason why shooters looking for ultimate accuracy (from 50 meters .22 LR 3 Positions Olympic Match, or prone English Match shooters, to 1,000 yards Palma Match shooters, to military or law enforcement snipers, etc.) will never shoot a rifle that they have no sighted themselves, because the variables in human nature, shooting form and recoil control techniques are such that no two shooters control recoil the same way.

This is the reason why British double rifles makers in the golden age asked their clients to come and shoot the rifle during the regulation process, because they realized that a critical variable in the double regulation is the control of the recoil and the yaw. The same .470 double rifle will assuredly shoots to different points of impact, and likely produce different group sizes, with 120 lbs Jack who rolls with the recoil and 230 lbs John who fights the recoil.

Of course, the effects are magnified with high-recoil rifles, but the principles also apply all the way down to .22 LR rifles. I shot pre-Olympic for about 5 years with an Anschutz 1913 Super Match 54 rifle that weighed 11+ lbs, and it is hard to believe that shooting something like that, prone, with competition sling, compression jacket, etc. still comes down to consistency in recoil control. With an 11+ lbs .22 LR rifle shooting low speed match ammo, for crying out loud, one would think that there is no recoil to control, right? Wrong...

Now get to .458 Lott or darn anything in between, and you get the implication: the biggest factor in shooting accuracy is recoil control and consistency in recoil control. The faster and bigger the recoil, the more difficult...

Beside the obvious: the caliber and load (specifically: bullet weight, powder weight, burn rate, and barrel timing, i.e. the time the bullet takes to exit the barrel), the factors at play include virtually anything you can think of: rifle weight, stock design, stock fit, recoil pad characteristics, shooter position, rifle support, shooter mass, shooting form, shooter clothes, etc. For example, a rifle will change point of impact (POI) subtly (or no so subtly) if you as much as change the recoil pad on it... It may not show much difference between a 3/4" and a 1" Decelerator, but experiment adding a slip-on absorbing recoil pad on a military rifle that has a steel butt plate and you will be surprised at the outcome...

So, the reality is that shooting with or without a lead sled does produce a shift of POI, not by feet mind you, but by an inch or two typically, because the recoil control dynamics change, even if we do not typically see it when shooting at game where, truth be told, we do not measure POI vs. point of aim as long as the bullet lands somewhere within a few inches of where it was intended and kills cleanly, but if you want to verify the lead sled effect, there is nothing simpler. Shoot 5 rounds with the sled, then 5 rounds without the sled, you will see a shift of POI, it may be big or small, depending on your technique, but it will be there, it is simply the physics of the application of forces.

I will be the first to say that as long as the shift of POI does not exceed 1" or 2", who cares !!! Heck the wobbling of the rifle on the sticks or in field shooting positions, sitting, kneeling, or, God forbid!, standing off hand, will create a lot more variation in the POI that the use or not of the sled, but you will never see a sniper or competitor use a sled to sight their rifle...

In the end, this is why some calibers (especially those that recoil fast and furious) have gained the reputation of being "difficult to shoot well." Of course there is nothing difficult in aiming them or pulling their trigger, and nothing inherently wrong with their ballistics, but keeping them pointed in the right direction under fierce recoil is difficult, especially when the recoil is fast - hence when the bullet still has a substantial portion of barrel to go through while the rifle moves a lot, and doing it consistently always the same way is even more difficult...

Changing the characteristics of the rifle (adding or removing muzzle brakes or suppressors, etc.) obviously change the dynamics of the recoil, hence the POI.

Then we can add the next layer to the discussion, which includes all the types of shooter errors (general category: flinch) caused by recoil that either scares or hurts, or both...

Some appear to be impervious to recoil but most of us are not, and this is why most of us, myself certainly included, shoot a .223 a lot better than a .458

Good post, One Day - thank you

 

[Longwalker]

I have had some puzzling misses in the field when using a couple different rifles of substantial recoil. The worst one was a Marlin guide gun .45-70 with heavy loads. It shot very well off the bench when rested firmly on front and rear sand bags. But in the field shot very low.
I figured out that the rear bag was acting like a hinge, stopping the butt from recoiling naturally, and so the muzzle was rising more than when shot offhand. I got better field results when I started shooting from the bench with the butt not touching a bag, but instead had the sandbag supporting my forearm and wrist of my trigger hand. Elbow of the trigger hand must also be free to move. I put my elbow on some soft padding or position so it is supported but hanging over the rear of the bench. Fore end supported by a firm grip, with that hand is resting on a sandbag.
This method duplicates the muzzle rise more naturally than when a rifle is rested solidly on sandbags. It also worked well once I started shooting my .450-400 Merkel and my 9.3x74r Beretta double rifles.
It is far less necessary with a modern straight stocked rifle like my Sako M85 Kodiak .375. I hardly notice any difference in point of impact vs resting technique when shooting that rifle, I assume because of the straight stock.

 

[Forrest Halley]

@One Day... Your post makes me smile. There is so much wisdom there. I too have fired the 54 and recoil consistency is very applicable even in such a small scale. You did leave out the different positions having different zeros, but it's a known to you and overlooked as having been covered in the varying recoil consistencies. How the double rifle people missed/dismissed this point is beyond me. Thank you for reiterating some things I knew and teaching me about bucking. That's new to me. I have never experienced it but now I will beware of it. I'm going back to zeroing my guns off good called shots offhand watching the sights lift.

 

[Red Leg]

Most scopes are designed to withstand the acceleration of recoil but not the deceleration of the jerk to a halt caused by the lead sled. If the lead sled were fitted so tightly to the rifle that the rifle couldn't move without carrying the lead sled along with it, recoil wouldn't be a problem. Unfortunately for the scope, there is enough slack in the connection between the rifle and sled to allow for the short burst of recoil, then the stop- which is what I understand is the source of damage to the scope.

According to whom? Specifically? I have used one for a decade. Lots of rounds and lots of rifles. Mine and others. Big caliber and small. I have never had a scope damaged. Not one. Never cracked a stock. A good friend is a nationally recognized custom ammunition loader. He uses one as well with the clients’ rifles. Never an issue.

@One Day I would also reiterate that I notice no change in impact between a lead sled group and simple sandbag supported group (unless it is the lead sled is typically a hair tighter); certainly not one to two inches. And as I noted, I use one extensively and consider myself an experienced and good enough shot to notice the difference.

A final point. I am hardly the first person to opine that most recoil is generated as gasses exit the muzzle rather than during the compression phase. In other words AFTER the bullet has left the barrel. Indeed bullet resistance actually counters recoil - that is an internal ballistics issue that becomes very important with 80 lb rounds fired from an artillery piece. Ergo, I would argue, with respect to accuracy, the real challenge of recoil is returning to target for the next shot.

Open sights are another issue entirely. Everyone sees the sight picture differently and everyone sees the sights differently depending how the rifle is held and supported. With scopes, it is far less an issue. In that case, focus and parallax are the main challenges between shooters.

 

[One Day...]

@One Day I would also reiterate that I notice no change in impact between a lead sled group and simple sandbag supported group (unless it is the lead sled is typically a hair tighter); certainly not one to two inches. And as I noted, I use one extensively and consider myself an experienced and good enough shot to notice the difference.

That is entirely the point, Joe. I suspect/believe that you fall in the category of "well-trained / well-practiced / far-above-the-average shooter" and that you likely have excellent recoil control technique, i.e. you do about as good a job as the lead sled does of controlling consistently the recoil, and therefore your POI shift with or without the sled is small enough to be lost in the typical 1" groups you shoot. As I stated: "you will see a shift of POI, it may be big or small, depending on your technique." Many shooters do not have your training, experience and extensive practice...

In truth, I too do not see much shift in POI whether I shoot from a forearm sand bag (I do not use anything under the rear stock) or from a field rest, but my field rest groups open up compared to my sand bag groups, and based on past experience shooting competitively, I expect that my larger field position groups hide the shift of POI inside them. All it takes is going from 1" groups from the bags (or sled) to 2" groups from field positions at 100 yd to hide a 1/2" shift of POI...

Many folks with less formal training, experience, practice, can see several inches of POI shift, especially when shooting high and fast recoil calibers, further compounded by one size fits all light rifles...

Forrest Halley is 100% correct, any competitor in .22 LR 3 Positions Olympic Match has at least 3 zeros: prone, kneeling, standing. I used to have 4 because we were shooting outside and winter clothing produced a definite different zero from summer clothing when prone. Admittedly, the shift of POIs was hardly an 1/8" to a 1/4" at 50 meters between winter and summer clothing, but it was enough to wander off the 10 ring into the 9, and it would cost you a highest score... I am sure that if I had been good enough I would have had different kneeling and standing zeros for winter and summer too, but my kneeling and standing groups were not tight enough to discern the shift of POI... (which is why I never made the selection...)

 

[Ray B]

According to whom? Specifically?

I presume those questions to be rhetorical since you then went on to provide your own explanation as to why my comments were incorrect. However I will answer, since I live in the United States the only maker of quality scopes that I had the means to contact was Leupold and Leupold customer service was the one that related stories of scopes that had been returned as damaged due to having been fired on heavily weighted lead sleds.

Some people need to brag, others don't.

 

[Ray B]

I am hardly the first person to opine that most recoil is generated as gasses exit the muzzle

Since you are so knowledgeable on the subject please explain to us less knowledgeable people how this is. Particularly, I'd like the physics presented for two examples. the propulsion effects of a .308" bore 180 grain bullet powered by a 100 grain charge of powder, 26" barrel, exit velocity 3400 feet per second compared to a .458" bore 500 grain bullet also powered by a 100 grain charge of powder, 26" barrel exit velocity 2500 feet per second.

 

[Red Leg]

That is entirely the point, Joe. I suspect/believe that you fall in the category of "well-trained / well-practiced / far-above-the-average shooter" and that you likely have excellent recoil control technique, i.e. you do about as good a job as the lead sled does of controlling consistently the recoil, and therefore your POI shift with or without the sled is small enough to be lost in the typical 1" groups you shoot. As I stated: "you will see a shift of POI, it may be big or small, depending on your technique." Many shooters do not have your training, experience and extensive practice...

In truth, I too do not see much shift in POI whether I shoot from a forearm sand bag (I do not use anything under the rear stock) or from a field rest, but my field rest groups open up compared to my sand bag groups, and based on past experience shooting competitively, I expect that my larger field position groups hide the shift of POI inside them. All it takes is going from 1" groups from the bags (or sled) to 2" groups from field positions at 100 yd to hide a 1/2" shift of POI...

Many folks with less formal training, experience, practice, can see several inches of POI shift, especially when shooting high and fast recoil calibers, further compounded by one size fits all light rifles...

Forrest Halley is 100% correct, any competitor in .22 LR 3 Positions Olympic Match has at least 3 zeros: prone, kneeling, standing. I used to have 4 because we were shooting outside and winter clothing produced a definite different zero from summer clothing when prone. Admittedly, the shift of POIs was hardly an 1/8" to a 1/4" at 50 meters between winter and summer clothing, but it was enough to wander off the 10 ring into the 9, and it would cost you a highest score... I am sure that if I had been good enough I would have had different kneeling and standing zeros for winter and summer too, but my kneeling and standing groups were not tight enough to discern the shift of POI... (which is why I never made the selection...)

We are likely talking past one another (it has happened before ), and it is also possible we are conflating the effects of position and hold with open sight picture and telescopic sights. I too am an old competitive smallbore shooter (Louisiana State Collegiate champion in '73!! - that is laughing at myself @bruce moulds not bragging) and I agree that everything alters to some extent in every position - all of which affects sight picture. My field and range experience with both military and personal firearms has been the same. In fact, all of my final sight-in shots with open sights are always done from a field rest (nowadays usually sticks). But scopes reticles are on a single plane, and in my experience at least, far less subject to the effect of position on sight picture. So, any difference between the rest (lead sled, sand bag, etc) and the field sight picture is not really much of an issue. I personally believe that is the actually greatest contributor to my observations of no detectable difference between the lead sled POI and the field.

I agree that "muzzle flip" can affect accuracy, but I don't think it is meaningful. We would both agree, that without a shooter and no hindrance (shoulder or lead sled) a rifle will recoil straight back with equal and opposite force as that generated by the firing of the projectile. Initial mitigation is rifle weight and bore friction (back to that in a bit). I was always taught that the initial recoil impulse (which does indeed begin at ignition) is relatively small until the bullet clears the barrel when the gas jet accentuates the perceived impact - essentially why muzzle brakes work. I am a history major, not a physicist, but let's say the typical rifle bullet leaves the muzzle in about 1 millisecond (I am deliberately doing easy math by the way - I tried to take my required college math classes with the basketball team ) and let's say a rifle moves 300 inches in one second, then it can only move .3 inches during the period of time the bullet is in the barrel regardless of how the firearm is held. So worst case, the rifle's point of aim is only influenced by whatever muzzle flip occurs in the first third of an inch of movement under recoil. I admit that .3 inches over extended ranges can be meaningful, but it also means we're actually compensating for only a small initial part of the recoil impulse.

Thus again, I think the real purpose of the vast majority of our technique is to mitigate against the perceived and anticipated movement of all stuff coming out the end of the barrel - not to mitigate the effect of actual muzzle flip. None of which has very much to do with multiplane sight picture other than make technique all the more demanding.

With respect to friction. I am not even sure a meaningful measurement could be made for a rifle. But it is a real input of the internal ballistics of say a 155mm artillery round. The opturating bands create friction in the bore, mitigating recoil and "flip" to some small extent which nevertheless is perceivable when engaging a target at 18 kilometers rather than 180.

 

[Red Leg]

I presume those questions to be rhetorical since you then went on to provide your own explanation as to why my comments were incorrect. However I will answer, since I live in the United States the only maker of quality scopes that I had the means to contact was Leupold and Leupold customer service was the one that related stories of scopes that had been returned as damaged due to having been fired on heavily weighted lead sleds.

Some people need to brag, others don't.

Sigh. Bruce, if owning a hundred dollar lead sled for a decade and using it extensively is bragging, then I guess I am guilty of whatever you perceive to be bragging. I admit that I haven't ever had to speak to Leupold customer service about one of their scopes that I damaged on a lead sled because I never have - and I have owned just a few. Though, I am not entirely surprised that a company rep would be happy to point a finger at something other than one of their own scopes when it was returned for repair. What I have heard and read is a lot of nonsense about lead sleds damaging scopes and breaking stocks, etc etc written or related by people who have never owned or used one. I suspect that the good folks at Caldwell would have had a difficult time staying in business if their product was actually destroying rifles and telescopic sights. I am simply relating my extensive actual experiences with one.

 

[Red Leg]

Since you are so knowledgeable on the subject please explain to us less knowledgeable people how this is. Particularly, I'd like the physics presented for two examples. the propulsion effects of a .308" bore 180 grain bullet powered by a 100 grain charge of powder, 26" barrel, exit velocity 3400 feet per second compared to a .458" bore 500 grain bullet also powered by a 100 grain charge of powder, 26" barrel exit velocity 2500 feet per second.

See above. Pretty bare with respect to the physics, but the math is simple enough.

 

[Red Leg]

Sigh. Bruce, if owning a hundred dollar lead sled for a decade and using it extensively is bragging, then I guess I am guilty of whatever you perceive to be bragging. I admit that I haven't ever had to speak to Leupold customer service about one of their scopes that I damaged on a lead sled because I never have - and I have owned just a few. Though, I am not entirely surprised that a company rep would be happy to point a finger at something other than one of their own scopes when it was returned for repair. What I have heard and read is a lot of nonsense about lead sleds damaging scopes and breaking stocks, etc etc written or related by people who have never owned or used one. I suspect that the good folks at Caldwell would have had a difficult time staying in business if their product was actually destroying rifles and telescopic sights. I am simply relating my extensive actual experiences with one.

And @bruce moulds the only reason I respond to the Lead Sled criticisms is because it has proven for me to be a wonderful tool for someone to use in sighting in a hard recoiling rifle. Lots of shooters struggle with recoil off the bench - experienced or novice. They become afraid of their own rifles; they don't properly sight them in; and they don't shoot them enough to become proficient. The lead sled gets them through those initial rounds and insures that they at least have a proper zero with their telescopic sight. For me in particular, it insures that I can sight in a new rifle and scope or verify a zero with an absolute minimum of shots from the bench. I don't like taking a beating sitting in a chair either.

 

[Red Leg]

And @bruce moulds the only reason I respond to the Lead Sled criticisms is because it has proven for me to be a wonderful tool for someone to use in sighting in a hard recoiling rifle. Lots of shooters struggle with recoil off the bench - experienced or novice. They become afraid of their own rifles; they don't properly sight them in; and they don't shoot them enough to become proficient. The lead sled gets them through those initial rounds and insures that they at least have a proper zero with their telescopic sight. For me in particular, it insures that I can sight in a new rifle and scope or verify a zero with an absolute minimum of shots from the bench. I don't like taking a beating sitting in a chair either.

LOL - 5 am - sorry to put your name in this string @bruce moulds !!!!! Obviously @Ray B I was responding to you.

Hope it's the early hour and not the virus?

 

[Shootist43]

Red Leg, a question for you. How much weight do you put on your lead sled? To me that is the key to the scope damage "thing." I too use a lead sled, but only with a couple of sandbags on it to somewhat dampen the effect of recoil. My shoulder absorbs the rest. If one puts enough weight on the sled to eliminate rearward movement something has to give, be it the stock or scope or both. My shooting technique always attempts to control "lift" whether on or off a lead sled. I haven't seen anyone comment on the effect that the anticipation of recoil has on shot placement and or group sizes. IMHO that may be the biggest contributor to the "equation."

 

[Red Leg]

Red Leg, a question for you. How much weight do you put on your lead sled? To me that is the key to the scope damage "thing." I too use a lead sled, but only with a couple of sandbags on it to somewhat dampen the effect of recoil. My shoulder absorbs the rest. If one puts enough weight on the sled to eliminate rearward movement something has to give, be it the stock or scope or both. My shooting technique always attempts to control "lift" whether on or off a lead sled. I haven't seen anyone comment on the effect that the anticipation of recoil has on shot placement and or group sizes. IMHO that may be the biggest contributor to the "equation."

I use a bag of shot.

 

[Shootist43]

Red Leg, Your use of a 25 lb. weight on the lead sled allows it to move as well. Especially when used with a 30-06 caliber rifle and above. That is why you've never experienced the scope failure others have. For an example a 375 H&H rifle weighing 9.5 lbs., loaded with a 300 Gn. Swift A Frame pushed by 74 Gn. of H4350 for a velocity of 2545 FPS
produces almost 43 ft. lbs. of recoil. Assuming the sled and the shot bag of lead weighs 30 lbs. It will move rearwards when fired. Put two or more bags of shot on that sled and bad things will start happening to your rifle stock, scope or both.

 

[Red Leg]

Red Leg, Your use of a 25 lb. weight on the lead sled allows it to move as well. Especially when used with a 30-06 caliber rifle and above. That is why you've never experienced the scope failure others have. For an example a 375 H&H rifle weighing 9.5 lbs., loaded with a 300 Gn. Swift A Frame pushed by 74 Gn. of H4350 for a velocity of 2545 FPS
produces almost 43 ft. lbs. of recoil. Assuming the sled and the shot bag of lead weighs 30 lbs. It will move rearwards when fired. Put two or more bags of shot on that sled and bad things will start happening to your rifle stock, scope or both.

Well, of course. The sled is designed by the manufacturer to use a 25 lb bag of shot (or seven lbs of sand). I would assume everyone would want to use it as it is designed to be used?