Vertical strings when hot?

[JamieD]

I am making final preparations for Zim in Aug. I not used to shooting when it is very hot.

Is it unusual to get vertical shot groups when it is hot 85-95 degrees and 70-85% humidy?

Both guns that are doing this the 416 is worse then the 375.

Both guns are in plastic stocks and freefloted.

I shoot 3 shot groups, I takes me 2-5 min. to shoot a group.

The groups run perfectly vertical between 1 3/4" to 4 3/4" it seem that I have something going on as the are so strait. Very little difference side to side. This makes me think that these guns could do much better.

Any incite would be good.

 

[Mike70560]

Jamie,

I would check to make certain your velocity is consistent. That is what comes to mind when I see vertical stringing, however at 100 yards it should not be that much.

Is your first shot placement consistent?

 

[JamieD]

I think that my velocity is fairly consistent, with my crony it is more of a guide than a science,

I need to shoot some more groups to check on first shot consistency, I've been trying to find out my problem, so different scopes, work on bedding, checking screws etc. So my groups have been moving around.

How do you hold a big boomer? I tend to hold it down tight to reduce muzzle jump. I see some people shooting with there off hand not even on the gun. What is the best way to hold a big gun of off the bench?

 

[enysse]

I get vertically strings with my 338 Win when it's hot like you said. My gun is a stainless steel, synthetic Remington 700 with Leupold 3.5x10.5 50 mm scope on top. The barrel gets so hot after shooting a group you can't touch it!

Shooting off the bench I hold my hand over barrel stock region....just ahead of the scope. How tight, depends on how tight I shoot offhand or off sticks. I never hold ahead of the stock....on the barrel only.

 

[DOC-404]

What rifles do have? What ammo are you shooting,factory or hand-loads?Hot hand-loads will give you vertical strings,even in MILD weather.Hot factory loads will definitely string in HOT weather,bet on it..! Never overheat your barrel,let it cool after every three shot group.

As for holding your rifle,firm grip,cheek bone on and tight in the shoulder.Keep your left hand on the stock as you normally would and DON'T touch the barrel.Also don't try to pull the rifle down into the rest to avoid muzzle lift.Try to 'ride' the recoil.Lastly,the nasty one,ask a fellow rifleman to watch you for flinching..!I've seen this being the answer to many rifles going 'walkabout'.Good luck.

 

[James.Grage]

JamieD

Are these the Rifles that you had re-bedded?

The following will cause bullets to walk upward or downward...

I was doing some reading and one of the things it mentioned for accuracy and consistency was that you needed to hold your rifle in the same place on the forearm.

They went into your bullet placement will change with the placement of your hand ahead or backward on the forearm....

One of there suggestions was to have your hand and resting areas near your front swivel stud (on stock with the swivel in the wood) they were trying to make sure it is the same for every shot.

 

[JamieD]

I found the reason for my strings.

I tried everything that I could think of, up load, down load, seating depth, different bullets, different powders. The day before yesterday was cool. I shot all day, even with a lead sled and past pad after 75-80 rounds of 375 RUM and 416 Rigby I wasn't sure I could hit a barn anymore. I finally put the Rigby away and decided that it wouldn't go to Africa, I couldn't get better than 3 1/2"-5 1/2" groups.

I decided to shot two more groups with the 375 one with the rifle on the rest and one with the gun in my had. I shot 4 shot groups rather than 3 hoping that I would find a pattern to the madness. By the third shot of the second group I could call the shots. The two groups could be laid on top of each other and see the holes on the second paper, two 4" groups that were a perfect match. My smith had said to try shooting without the magazine, I thought he was full of it, but after these groups that was the only thing that I could think of that would change from shot to shot that constantly. I toke the magazine out and shot another 4 shot group with the 375, 3/4" after 75-80 round of cannon fire for the day. I had a sore head and my hands were shaking. so I didn't shoot the 416 again that night. The next morning I still felt I wasn't up to it but couldn't wait, shot a 3 shot group the paper was tore but looked to be a .3-.4" group. and I've shot a couple groups out of each that are very similar.

I couldn't get a hold of Wyatts on the phone so I e-mailed him he responded today and said he would be back in town Fri. and would call me. I hope he can give me some answers.

Thought some of you would find this very interesting, I sure would if I didn't have two expensive one shooters for a trip in 20 days.

 

[James.Grage]

JD

Thanks for the up date...i only have one rifle with a drop out box...

Who would have thought..

 

[sestoppelman]

When shooting my rifles from the bench I dont touch the rifle ahead of the trigger. I use my left or off hand to control the bag under the buttstock for shifting up and down. I see guys with their off hands holding the forearm down or over the top and stuff like this... Just keep your off hand away from the gun all together and use it to squeeze the rear bag and nothing else. One thing that drives me nuts is watching guys too lazy to remove their sling and placing the forearm on top of the sling so it can slide all over the place while shooting. Take the bloody thing off the gun at the bench! And except for very heavy barreled Sharps type rifles never rest the barrel on the bags, only the forearm. Its amazing to watch some guys shoot. You wonder did they ever read a book or a magazine on proper shooting?

 

[JamieD]

I try to make shooting of the bench closer to field conditions, leave on sling, hold forearm. have shells in magazine, shell holder on stock. DO NOT TOUCH BARREL. I have a friend that does this and he can never get why his groups move.

I know that it doesn't make for the best accuracy but if I have to put my gun over a rock or limb the sling will be there so I want to always have my guns in there hunting clothes. If I shot single shot of of the bench I wouldn't have found this issue.

Everyone has there own ways to do things. Some work and some don't.

Thanks for following the thread. I'll let you know what Wyatt has to say. He builds sniper rifles so he should know how to fix this.

 

[sestoppelman]

Well the point of shooting from the bench is really more about the gun than you or the field. In order to find good loads etc one must remove as much interference as possible. AFTER finding good loads and confirming that the rifle shoots properly then fine, hang all the gingerbread on your gun and shoot from FIELD positions and off STICKS or hanging upside down from a sausage tree but not until. Just my very Humble Opinion.

 

[James.Grage]

every one does things different however we are still trying to reach the same results...

We want to hit the target we are shooting at...

With that said once you have your rifle sighted in then you are able to do your field style shooting...

Large rifle are a pain in the shoulder to shoot a great deal from the bench...

that is why i like to go prairie dog hunting with my rifle after initial sight in...

 

[JamieD]

sestoppelmen

I would love to see the pictures of "upside down from a sausage tree". I can never get how to do the laughing face.

Have a good day!

 

[JamieD]

I spent the day yesterday at the smith, no good ideas, talked to Kevin Wyatt 2-3 times no go, finally we decided to open the receiver more front, back and sides. This way the magazine doesn't touch the receiver at all. This helped some. Then I put some shims under the bottom metal to lower the magazine some. This way any movement has less effect on the harmonics of the rifle. This helped some more the first group was 2" much better than 3 1/2"-5 1/2 and it wasn't straight vertical. I added a little more shim and put some electric tape on both sides of the magazine to reduce movement.

We"ll see what that does tomorrow.

 

[sestoppelman]

I must have missed somewhere the particular rifle thats giving you fits, what is it?

 

[JamieD]

Two rifles both started life as Rem. 700 BDL 7mm-Mags, old ones no letter in SN. One is now a 375 RUM with MPI stock. The other a 416 Rigby with a McMillan stock and Pacific Tool and Gauge bolt. Both have Jewell triggers, have been pillar bedded. They both had Seekins magazines first but we couldn't get them to feed very well. We sent them to Kevin Wyatt to have him install his magazine system. When they came back they fed great but we had the stringing issue. It was quit hot when they came back that is why I blamed the heat for the stringing. After a cool day I realized it had to be something to do with the magazines.

I think with some TLC I'll get them to shoot, maybe not what they would single shoot. The 416 seems to be very touchy about anything that will change the harmonics. After I get some consistency I may try to give it a pressure point in the forearm to see if that makes it less picky. For now I just need to get some consistent groups hopefully under 2"

 

[sestoppelman]

Jaime, I hate to say this but it sounds like in the attempt to fix a nonexistent problem with all kinds of modifications, you created a monster, a fussy gun. Its too late now you must either fix the new problems or take something else if you had the time. 100 percent reliability is the prime consideration.

 

[James.Grage]

ses...i would have to agree with you...

JamieD i see that you live in Iowa i am not sure what part of Iowa...i know a top notch gunsmith in Minnesota (one of the best in the us) that if given the time would be able to make your rifle function...however he is extremely busy..however he would fit you in...if i were you, I would call Laib's and drive up and take my rifle to him and see if he can make the repairs you need. i send my guns to him when i need things done...

Jaime, I hate to say this but it sounds like in the attempt to fix a nonexistent problem with all kinds of modifications, you created a monster, a fussy gun. Its too late now you must either fix the new problems or take something else if you had the time. 100 percent reliability is the prime consideration.

 

[JamieD]

We found the problem !!!!!

I'm not positive what it was. The last time I visited the smith we duracoated the bolts to tighten up the actions and we opened up all the way around the bottom metal to relieve any pressure points.

I' guessing that it was the bottom metal as it was fitted very tight. I thought this was a good thing but I think that it was so tight that it was causing harmonic changes as the weight changed in the magazine.

I'm getting 3/4" groups out of the 416 in very hot weather, and 1" out of the 375 but the groups were horizontal rather than vertical. Tonight I took the scope of to check the base and it was loose. I guess that it is a bad idea to put a alum. base on a gun that kicks that hard. Although I probably wont put this many rounds through it the rest of my life. I found some odd screws to use so I can shoot it (the screws were all shot) and ordered a steel base. This should tighten the groups even farther.

Thanks for the advice you guys gave.

 

[sestoppelman]

I hope that solves the problem especially since you are soon off hunting! Good luck!!