Peak pressure and recoil profile

[Grumulkin]

I do have an observation: it seems to me that bigger fellas feel the recoil more than little guys/gals.

That is urban folklore.

http://www.orchardphoto.com/460Weatherby.m4v

Six feet 10 inches and 310 lbs.

 

[colorado]

Typically speaking, recoil is a function of a huge number of things. To accurately determine recoil, you would need to have a huge amount of info but it can be reasonbly calculated via calculators. The only things it can possibly be a function of are: bullet weight, bullet velocity, powder weight, mass of air in the barrel in front of the bullet (small but there) and gas exit velocity. The last one is not as significant as the others but it would be important in say, a shorter rifle barrel where pressure is still very high by the time the bullet leaves the barrel. Conservation of Energy has problems with it when figuring recoil because energy can be dissipated in a plethora of different ways, Barrel heat, friction, shockwave as the gas exits the barrel, heating the air in front of the bullet via supersonic shockwave (assuming bullet is supersonic.) Conservation of momentum would be the best way for the average person without a lot of Newtonian and Fluid Dynamics calculations or software, to determine relative recoil. It goes something like this:

If you just want to see my honest opinion, skip all the math and read the last paragraph.
Momentum(p)=M*V, Let's say we have a 9.5lb gun and a 400 grain bullet with 90 grains of powder propelling it to 2,400 fps

p(bullet)=(400/7000)lbs + (90/7000)*2400f/s
p(bullet=0.0700lbs*2400f/s= 168lb*ft/s

So p(rifle) has to equal p(bullet)

p(rifle) = 168lb*ft/s
168lb*ft/s = 9.5lb*V(rifle)
(168lb*ft/s)/9.5 = V(rifle)
V(rifle)=17.684 f/s

Using this we can determine that the recoil energy of the rifle:

e=1/2MV(rifle)^2 with M being 9.5lbs/32f/s(gravity)
e=(.5)(0.297slug)(17.684f/s)^2
e=46.439ft*lbs

This is very simplistic because it doesn't take into account the rocket effect as it changes depending on how much pressure is left at the muzzle and the mass of the gas being expelled. But it gets you the recoil on a closed system. the rocket effect will typically add between 25%-35% to the total recoil depending on several factors. I am not going to get into all the calculations for rocket exhaust velocity and such because people are probably sick of reading my post as it is.

So I say all that to say that the pressure spike is not going to have an appreciable difference in the felt recoil. Time in the bore and exhaust velocity are what will determine if it is a sharp smack or a push BUT... I have a feeling that you aren't going to notice a difference between an impulse that last .0015 seconds and one that lasts .0022 seconds. It is my opinion that recoil velocity, stock design, recoil pad design and the clothes you are wearing at the time you shoot are going to have a much more drastic effect on percieved recoil than any sudden spike in pressure. I know there are a huge number of calculations left out but... most people don't care about the math... I just love it!

I also find this fascinating. In my 500 Jeffery, I'm using H4895 (kind of fast) with a 570g bullet. I've topped out at 2400 fps, but my hunting load is 103g for a consistent 2300 fps and sub MOA groups. I've gone faster with a lot more IMR4350, but man with 120 plus grains of IMR 4350 and a 570g bullet at just over 2500 fps it's kind of ouchy. At that level nothing is a push.

 

[ChrisG]

Chris - OK so I am going to out you as an engineer! It's OK though my Dad is one and I recognize your type and have been trained in your ways! Go to U-tube and look up a video called "the knack". I think the problem is more complex and has to do with the rate at which the work is being done. This must have a very sharp initial spike with exponential decay for the Remi and a more gradual build and decay for the Rig. I know my rifles that operate at high pressures are more annoying to shoot. Now to measure this or try it out is the question. My 416 Rigby gets out of 10 day cooling off in 2 hours and 4 minutes. Anyone have a 416 Remi and lives within driving range of LA?

Rick Hill[/QU

Mechanical Engineer, yes... you caught me. Not a ballistics engineer so... my analysis may be completely flawed.

I agree that it might have a slight effect. My point is that if the Rigby is a slow push and the Remington is a sharp smack is, unless the rifles are EXACTLY the same except for caliber, with the same rate of twist, mass, recoil pad, stock and length of barrel, and you were wearing the same clothes then it would be impossible to judge accurately. To pit a Winchester M70 against a CZ 550 is not going to tell much other than one is more comfortable. Now, if someone had 2 identical CZ 550s, took both to the range the same day and fired both side by side, then we could probably judge something. Volunteers?

I will say this, I have owned or do own a .338 Win, a.375 h&h and a .416 Ruger. None of them are unbearable but I don't feel like either "pushed" harder than the others. The smack just got harder as I went from .338-.375-.416. All different guns mind you but the difference was definitely real. I don't know why people say that a .338 shooting a 250 at 2700FPS smacks harder than a .375 shooting a 270 at the same speed unless the h&h had a kickeez on it and the .338 a steel butt plate. I'd wager that, were they the same rifle, the .375 would hit you decisively harder. Again... I am not a ballistics engineer and I don't design rifle cartridges. It's just what the math bears out. You can say Newton was wrong and it's all just theory, but we didn't get to the moon on perceived physics... math got us there.

 

[mark-hunter]

However, math could be out of reach for us, poor souls and ordinary average Joe hunters...

For example:
Rifles with strong recoil, generally will have straight stock. (not, for example hog back, or Monte Carlo... etc...)
Also, on some rifles, a muzzle brake is fitted. (there are many different designs of that, too)

So, how to put stock design, or shape, and various designs of muzzle brakes in mathematical formula, to get mathematical value of recoil?

Stock design may divert a part of recoil in other directions, especially as barrels center of gravity is higher and above of the stocks center of gravity, and when the recoil movement starts, there are vectors involved. But putting it in numbers, is not that simple, at least not for me.

 

[Ray B]

I have found there are three aspects of recoil that are undesirable 1. jolting my head,neck 2. hitting me in the face, and 3. beating-up my shoulder. According to Elmer Keith the reason for the forward sloping cheekpiece was so that the rearward motion of the rifle would push the stock away from the face. additionally, having the rifle supported at the butt as close to inline with the bore as possible (and still allow the bolt to cycle) minimizes the rising of the muzzle resulting from the rearward push seeking the avenue of least resistance. If a recoil distribution pad is worn on the shoulder it will disperse the recoil over a larger area resulting in less "per sq.in" push. I suppose I'll still get headaches from having my neck snapped from the recoil, but at least my face and shoulder can abide by the range session. If I wear stout hearing protection, the noise factor is also alleviated.

 

[mark-hunter]

As I have (so far) never been hunting in Africa, I had no experience on really hard kicking tropical calibers.
The strongest I ever tried on range was 375 H&H, from standing position, and that was manageable.

However, there is also a 4th aspect of recoil, and that is effect on my wrist.
As I have once, some years ago, had broken wrist, cumulative effect of recoil is felt as a pain in the wrist, after some number of shots from prone position. I noticed that this will depend of caliber (power), weight, and ergonomics (stock design).

And then, I can feel effects or adverse effects of recoil, on the wrist.

For example, shooting 8x57 mauser from classic military 98k (with steel but plate), results in my slight wrist pain after 20 shots.
30-06, bavarian stock, without scope (scope is 520 grams, plus some weight on mounts) - results in pain after 12 shots.
However, same 30-06 rifle with scope and mounts - no pain at all. (added weight about 600 grams, about)

Same as shooting very same 8x57 caliber, from hunting rifle, hog back stock, rubber pad - no pain at all, can go on all day long.

What I want to say, ergonomics (and weight) of rifle, play very important role in handling recoil, when it comes to individual sensibility of shooter.

Oh, yeah, not to forget - rifle mechanism, as well plays a role. Semi auto rifle will reduce recoil very much.
In gas operation system, when moving parts start going backwards, and before the bullet leaves the barrel, it reduces recoil significantly.

 

[ChrisG]

Typically speaking, recoil is a function of a huge number of things. To accurately determine recoil, you would n eed to have a huge amount of info but it can be reasonbly calculated via calculators. The only things it can possibly be a function of are: bullet weight, bullet velocity, powder weight, mass of air in the barrel in front of the bullet (small but there) and gas exit velocity. The last one is not as significant as the others but it would be important in say, a shorter rifle barrel where pressure is still very high by the time the bullet leaves the barrel. Conservation of Energy has problems with it when figuring recoil because energy can be dissipated in a plethora of different ways, Barrel heat, friction, shockwave as the gas exits the barrel, heating the air in front of the bullet via supersonic shockwave (assuming bullet is supersonic.) Conservation of momentum would be the best way for the average person without a lot of Newtonian and Fluid Dynamics calculations or software, to determine relative recoil. It goes something like this:

If you just want to see my honest opinion, skip all the math and read the last paragraph.
Momentum(p)=M*V, Let's say we have a 9.5lb gun and a 400 grain bullet with 90 grains of powder propelling it to 2,400 fps

p(bullet)=(400/7000)lbs + (90/7000)*2400f/s
p(bullet=0.0700lbs*2400f/s= 168lb*ft/s

So p(rifle) has to equal p(bullet)

p(rifle) = 168lb*ft/s
168lb*ft/s = 9.5lb*V(rifle)
(168lb*ft/s)/9.5 = V(rifle)
V(rifle)=17.684 f/s

Using this we can determine that the recoil energy of the rifle:

e=1/2MV(rifle)^2 with M being 9.5lbs/32f/s(gravity)
e=(.5)(0.297slug)(17.684f/s)^2
e=46.439ft*lbs

This is very simplistic because it doesn't take into account the rocket effect as it changes depending on how much pressure is left at the muzzle and the mass of the gas being expelled. But it gets you the recoil on a closed system. the rocket effect will typically add between 25%-35% to the total recoil depending on several factors. I am not going to get into all the calculations for rocket exhaust velocity and such because people are probably sick of reading my post as it is.

So I say all that to say that the pressure spike is not going to have an appreciable difference in the felt recoil. Time in the bore and exhaust velocity are what will determine if it is a sharp smack or a push BUT... I have a feeling that you aren't going to notice a difference between an impulse that last .0015 seconds and one that lasts .0022 seconds. It is my opinion that recoil velocity, stock design, recoil pad design and the clothes you are wearing at the time you shoot are going to have a much more drastic effect on percieved recoil than any sudden spike in pressure. I know there are a huge number of calculations left out but... most people don't care about the math... I just love it!

I just realized that I made a mistake in my calculations and I wanted to fix it before someone points it out and says I am a horrible engineer.
The momentum calculations are wrong because I used weight instead of mass so the correct numbers are:
p(bullet)=p(rifle) 5.25lb*ft/s
Everything still works out after that I just wanted to clear my name I'm done now

 

[Ray B]

It's that nasty acceleration of gravity thing. Oh to be in outerspace!!

 

[Rick Hill]

ok i own 416RM and have shot friends 416rigby and we both say my 416RM whacks more, hows that for some science! unscientificalls the rcoil in my 416RM is sharper and faster rigby more big push. but who cares in the end we each love our guns and they are just the perfect recoil to us

I still vote to actually measure the recoil vs time characteristics and develop rounds that maximize performance and minimize self abuse. I had the 404 Jeff out 2300 fps with 400 Gr @ 10 lbs and the 416 Rigby 2400 fps with 400 Gr @ 10 lbs . Both have the same LOP, stock design, weight and shooter. All I can say is that last 100 fps cost a lot more recoil, blast and muzzle flip. Even adding a 1 lb scope to the Rigby still left a huge advantage in favor of the 404 Jeffery. The Jeffery was very surprisingly a pleasure to shoot, a sort of shorter focal push. The Rigby was a longer more intense shove with a lot more muzzle flip. Maybe we can grade recoil on rounds per shooter headache. Myself 20+ for the Jeff; 10 for the Rigby and 8 for my 450 NE. The Jeffery earned itself a nice scope and a smile when I look at it.

Rick

 

[colorado]

I still vote to actually measure the recoil vs time characteristics and develop rounds that maximize performance and minimize self abuse. I had the 404 Jeff out 2300 fps with 400 Gr @ 10 lbs and the 416 Rigby 2400 fps with 400 Gr @ 10 lbs . Both have the same LOP, stock design, weight and shooter. All I can say is that last 100 fps cost a lot more recoil, blast and muzzle flip. Even adding a 1 lb scope to the Rigby still left a huge advantage in favor of the 404 Jeffery. The Jeffery was very surprisingly a pleasure to shoot, a sort of shorter focal push. The Rigby was a longer more intense shove with a lot more muzzle flip. Maybe we can grade recoil on rounds per shooter headache. Myself 20+ for the Jeff; 10 for the Rigby and 8 for my 450 NE. The Jeffery earned itself a nice scope and a smile when I look at it.

Rick

If you're getting a headache you should stop and fix something, like don't shoot from the bench without a lead sled or a sand bag. A headache may mean a mild concussion. Having boxed golden gloves in my teenage years, having a headache after sparring or a match meant taking a week off.

 

[mark-hunter]

Gents,
In order to follow better this meaningful discussion, as I have never tried serious tropical caliber, except 375 H&H, for all of you who have experience in more then one, could you advise in your opinion which of the African 40-ies calibers will have the strongest recoil?

Or, opposite, which one will have most comfortable recoil? It seams that 404 Jefferey is one of the softest? Am I wrong in this?

Thanks!

 

[Ray B]

A Win 70 458 had the factory 22" barrel on it and it was replaced with a CP Donnelly 24" barrel that weighed 13 oz more, bringing the total weight to 10 lb 11 oz. The 500 grain bullets, with the same loads gain over 50 fps in the new barrel but the perceived recoil seems noticeably less. The powder is Rl 7, so it is at the fast end of the suitable powders. So: what would increase the recoil? the increased muzzle velocity. What would decrease the recoil? the added 13 ounces, the location of the weight (out on the barrel, decreasing the lift), the extra length moving the blast 2" forward, and the decreased "jet" affect from having 2 more inches for the pressure to drop. I don't know how all of these factors play into the movement of the rifle when it is fired, but I do know that when I fired it with the original barrel and full power loads it was "attention grabbing". While shooting the new barrel certainly leaves no doubt but that it fired, I can concentrate on "follow through" and keeping my focus on the target through the firing process. Or maybe it's just that I'm more accustomed to it and knowing what to expect, I can concentrate on the matter at hand.

 

[PHOENIX PHIL]

Gents,
In order to follow better this meaningful discussion, as I have never tried serious tropical caliber, except 375 H&H, for all of you who have experience in more then one, could you advise in your opinion which of the African 40-ies calibers will have the strongest recoil?

Or, opposite, which one will have most comfortable recoil? It seams that 404 Jefferey is one of the softest? Am I wrong in this?

Thanks!

A bit difficult to answer your questions with the number of variables that come into play. The caliber I disliked the most was .416 Rigby. I had a CZ in this caliber. I'm also a hand loader afflicted with the penchant for loading my rounds to capacity. In a modern rifle, the massive brass of the .416 Rigby can be loaded with 100gr or more of powder. I did not chromo my loads, but would guess the 400gr bullets I loaded were exiting the barrel at 2500fps or more. This was just too much. I could shoot the rifle and quite accurately so, but I did not enjoy it at all. On the range after only a few shots I was done.

I now own a .458B&M which is a wildcat caliber with ballistics between a .458Win and .458Lott. It will get your attention to be sure, but the stock design as well as somewhat slower velocity of the bullets makes this much more pleasant to shoot.

Regarding your .404Jeff question, I would agree that it is the least punishing. You would not be giving up anything if you decide on a rifle in this caliber.

 

[Rick Hill]

If you're getting a headache you should stop and fix something, like don't shoot from the bench without a lead sled or a sand bag. A headache may mean a mild concussion. Having boxed golden gloves in my teenage years, having a headache after sparring or a match meant taking a week off.

Roger the lead sled!

 

[ChrisG]

Gents,
In order to follow better this meaningful discussion, as I have never tried serious tropical caliber, except 375 H&H, for all of you who have experience in more then one, could you advise in your opinion which of the African 40-ies calibers will have the strongest recoil?

Or, opposite, which one will have most comfortable recoil? It seams that 404 Jefferey is one of the softest? Am I wrong in this?

Thanks!

As Phil said, It depends on so many variables... but all elses being equal and using factory loads, my best guess would be in this order going for least recoil to most: 450-400 NE, 404 Jeffrey, 416 Ruger, 416 Remington, 500/.416NE/ 416 Rigby/.425 Westley Richards, 416 Weatherby, and then they go up from there. I can tell you that when I went from .375 H&H to .416 Ruger, the recoil difference wasn't all that noticeable standing, but benching the rounds. At the bench, I can shoot probably 10 .375 H&H rounds (300grains @ 2550fps) vs. about 4 .416 Ruger rounds (400grains @2,350fps). Thats pretty much my limit. Of course, Ruger builds the Hawkeye African to weight only 7.75 lbs empty and with the scope mine only runs about 8.5lbs. So it slaps you pretty good with that little thin Hard rubber "pad". My H&H weighs 9.75lbs with scope and 4 rounds loaded.

 

[PHOENIX PHIL]

As Phil said, It depends on so many variables... but all elses being equal and using factory loads, my best guess would be in this order going for least recoil to most: 450-400 NE, 404 Jeffrey, 416 Ruger, 416 Remington, 500/.416NE/ 416 Rigby/.425 Westley Richards, 416 Weatherby, and then they go up from there. I can tell you that when I went from .375 H&H to .416 Ruger, the recoil difference wasn't all that noticeable standing, but benching the rounds. At the bench, I can shoot probably 10 .375 H&H rounds (300grains @ 2550fps) vs. about 4 .416 Ruger rounds (400grains @2,350fps). Thats pretty much my limit. Of course, Ruger builds the Hawkeye African to weight only 7.75 lbs empty and with the scope mine only runs about 8.5lbs. So it slaps you pretty good with that little thin Hard rubber "pad". My H&H weighs 9.75lbs with scope and 4 rounds loaded.

Replace that hockey puck of a recoil pad with a Limbsaver or Pachmayr, get a PAST pad to wear on your shoulder and you'll get more shots off the bench.

 

[Velo Dog]

Gents,
In order to follow better this meaningful discussion, as I have never tried serious tropical caliber, except 375 H&H, for all of you who have experience in more then one, could you advise in your opinion which of the African 40-ies calibers will have the strongest recoil?

Or, opposite, which one will have most comfortable recoil? It seams that 404 Jefferey is one of the softest? Am I wrong in this?

Thanks!

Hello mark-hunter,

If you decide to get a .40+ caliber "African rifle", hopefully you are a hand-loader.
If not, I highly recommend that you take up hand-loading your own ammunition.
That way, you can start with the lower velocity / pressure data in your manual.
This will noticeably reduce recoil, until you get somewhat used to it.
Then, if you want to, you can ease your way up toward learning to tolerate heavier recoil.

Regarding exactly which of these decent kickers to get:
Actually, you cannot go wrong with a .375 H&H.
However, after firing a friend's Mauser .404 Jeffery just like others here, I want one.
Unable to locate an affordable .404, I eventually caved-in to buy a CZ 550 Magnum, in .416 Rigby from Cabela's, (during an "over-stocked sale") a few years ago.
I only paid $800. US for it, new in the box, whereas at that same time, CZ advertised pretty much the same rifle but in .404 Jeffery, for over $3,000. (!?!?!?!!) no thanks.

Anyway, not being fond of recoil, I load my .416 down to the good old Pre-War .404 ballistics - 400 grainers at just a whisker over 2100 fps.
(I think my recoil outlook is called being a "sissy").
This reduced .416 Rigby load requires a spacer between powder and bullet, in the cavernous Rigby case, in order to avoid hang fires.
I promise you, hang fires in this caliber are very sporting to put it mildly, even at "only" .404 equivalent ballistics.
The recoil is noticeably less than today's standard Rigby load of 400 gr at around 2350 fps.

Also worth mentioning is the .458 Lott.
Rifles for it are common and affordable (I am partial to the large and robust CZ 550 Magnum bolt action).
.458 Diameter bullets for hand loading are also quite common, and available in various weights / shapes as well.
You can load this cartridge up or down as you see fit.
IMO, the .458 Lott is about the only cartridge developed since perhaps around the late 1940s or 1950s that was worth the effort.
I load my Lott down a bit as well.
With 500 grainers, going "only" a little over 2100 fps, it duplicates the old .450 NE ballistics, forever considered very adequate, even for huge grumpy bull elephant.
This load generates noticeably less recoil than the standard spec load of 500 grains at about 2300 fps.
Also in this cartridge, loaded with a 400 grain Swift A-Frame, I would merrily hunt almost anything on earth.
Loaded with 500 grainers, (soft or solid appropriate to the animal), I would hunt anything that walks.
The .458 Lott is a very excellent choice for anyone wanting a more powerful rifle than the .375.

Blah, blah, blah out,
Velo Dog.

 

[ChrisG]

Replace that hockey puck of a recoil pad with a Limbsaver or Pachmayr, get a PAST pad to wear on your shoulder and you'll get more shots off the bench.

It's funny you mention that. I can shoot 4 off the bench without the PAST on. With it my limit is about 6. It still hammers you pretty good off a bench even with the pad on. I already bought a 1.15" thick Pachmayr with the cushion cells and I have it all drilled out and the pad marked. I just have to sand it to fit. I may also add a half a pound lead rod into the buttstock... we'll see what the new pad does first. It is really nice to carry though!

 

[colorado]

I recommend also using a slip on Limbsaver recoil pad for the bench in addition to your decelerator pad. The bench is tough. Offhand is easy. I just use the bench for load development and sight in. After that it's either offhand, sitting or kneeling. I use a lead sled for any extended shooting from the bench (load development) but I know a lot of people have issues with them. I only put 25 lbs on the sled, with that much weight the 500 picks the whole thing up and usually knocks off my ear protection lol. I should have my son take a video

 

[375 Ruger Fan]

Realguns.com has an article on the 416 Rigby and graphically compares it with the 300 WM, in terms of chamber pressure and velocity. Agree with using a lead sled with only 25 lbs when shooting the big boomers on the bench. With 25lbs, the recoil is managble and the sled will slide. Load it heavier and you run the risk of doing damage to your stock.

http://www.realguns.com/archives/179.htm

Also, a recoil calculator is available: http://www.realguns.com/calculators/recoil.html