Verticle Problems

[moose1223]

My Son shoots F-TR .308 and has recently switched to Berger 215grn bullets 43grns Varget 28 inch barrel with 1:10 twist. The gun loved the 175grn sierra matchkings but the team he shoots with all switched to the 215s with excellent results so he follwed suit. Now horizontal is much better in the wind but the vertical is just to much and he is dropping to many points. The things we have tried are to many to list such as load development, bags, bi pods, bullet jump, and extended the throat.
Anyone have similar problems and/or advice.
We hope to have this figured out before Nationals and Worlds

 

[PhulesAu]

SWITCH BACK.

 

[BoydAllen]

Wild guess, try adding weight to the muzzle, something improvised, mounted solidly, a decent amount. If it shows a difference, play with variations, or raise or lower the load a half grain, depending on if you have room for the powder, and can take some more pressure.

 

[22BRGUY]

Many smarter and more experienced than I but I would suggest finding the "balance point" of the rifle. My guess it would be much closer to the stock end than the muzzle end. If that's the case or whichever, try to add or subtract weight accordingly. I've heard and believe that the "balance point" should be in about the middle of the action. Others please correct me on this.
Thanks

 

[Lapua40X]

... I would suggest finding the "balance point" of the rifle. My guess it would be much closer to the stock end than the muzzle end....

I tend to agree with this idea, except I prefer the balance point to be slightly forward of the action so the rifle is just slightly muzzle heavy for this type of shooting.

 

[BoydAllen]

I have moved a tune node to a slightly lower charge by adding weight where I mentioned. I was specifically not addressing rifle balance, but something that gives somewhat the same effect of a tuner. I have and have tested several different tuners. Weight at the end of the barrel slows its natural rate of vibration slightly, and can make a node come down to a slightly lower velocity and pressure. If you are as high as you can go, out of tune, and need to keep the velocity, this can be one way to have your cake and eat it too.

 

[savagedasher]

What kind of action if it is a savage the rear bolt helps to take vertical out a hard rear bag cause the same problem .try moving the rear bag location an thumb pressure on the stock can cause it or the lack of. The gun has more recoil with the bullet weigh change.When you have tried all that then go to what the bench rest shooter do speed it up or slow it down. Good Shooting Larry

 

[BradY]

First off before doing anything drastic, did he do any load development or just use the same load the rest of his team do? Every rifle is different so it may not actually be in tune with that load. Vary the powder charge up and down if its safe to do so. That way he can see if the vertical can be controlled. If its safe to do so I would suggest a quick test of 3 shots each at 300yds 42, 42.3, 42.6, 42.9, 43.2 and 43.5gr with the current seating depth, primer and case combo in that bullet. Might find that 43gr is giving vertical but 42.6 or 43.2 wont. If you find something that looks quite good in that test start shooting strings with it to see if it will agg. Can also run that load over a chrony to see what the ES is like.

 

[moose1223]

Thanks guys, these are great thoughts
I am leaning toward the balance idea. We had some improvement with rear bag type and placement. During load development we had no real noticeable changes in group size over a large range of loads. We have pushed the throat out .050 which allowed an additional 1grn before we seen pressure. We also tried a weight(12 oz) on the muzzle and that seemed to help with the occasional flier out the bottom and top but other than that no real change. We also took the gun totally apart and checked that everthing was tight and no change. This gun was spot on with 175 and 185 maintaining a 4 inch vertical at 1k. Maybe the sweet spot is very narrow. I guess i am being stubburn by sticking with the 215s but we have plenty of them and the 175 and 185 are scarce, besides that i will not be happy until i figure out this problem.

 

[watercam]

Send a PM to Sleepygator. He is a Champion F-Open shooter who was an engineer for Barrett Rifles. He has been through this problem several times over with various bullet/cartridge changes and will have good, solid advice for you. He shoots bullet weights up to 230 gr. in the .308 and 300 WSM.

 

[22BRGUY]

Think I have a problem with words...I have a picture in my minds eye but in looking at what I wrote, I didn't describe it well at all. Anyway, I meant to say it would seem from what you said, that the rifle may be stock heavy as opposed to muzzle heavy if you check for the balance point....I agree that is is better to have a rifle a little more muzzle heavy especially with heavier bullets that will probably recoil more. I thought Boyds idea made perfect sense as well to slow down the barrel vibration and make the rifle act as though a lighter bullet is being shot. As always, great post and info and hope helpful.

 

[BoydAllen]

No, you don't have a problem with words. You write just fine. Keep it up.

Boyd

 

[22BRGUY]

Thanks for encouragement Boyd, but I always do appreciate when you guys help clarify and /or correct me, but most of all appreciate how you and the other good, knowledgeable and experienced guys here are so willing to help and offer other ideas....what a great group this is!!

 

[Glenn Powell]

I am not a competition shooter and have yet to shoot groups past 500yds. So take this for what its worth. You did not mention velocity with the heavy bullets. Are they still stable at 1000? I only ask because I always read about being mock 1.25 at the target. Just a thought.

 

[CatShooter]

I am not a competition shooter and have yet to shoot groups past 500yds. So take this for what its worth. You did not mention velocity with the heavy bullets. Are they still stable at 1000? I only ask because I always read about being mock 1.25 at the target. Just a thought.

Bullets do not have to be traveling at Mach 1.25 to be stable - that is a myth.

There are many shooters that shoot past 1,000 yds and at distances that bullets are traveling at Mach <1.0, without ill effects. I have shot at 1,900 meters, with no problems.

 

[savagedasher]

Gun balance bags and velocity normally cures it. My self I also use a RAZ tuner brake. 4'' or less at 1000 yd is normal. Good Shooting Larry

 

[moose1223]

Most of the testing was in the 2500 to 2650 fps range which should be well above the mach 1 threshhold for 1k yards with 215s

 

[Tim Singleton]

What kind of action if it is a savage the rear bolt helps to take vertical out a hard rear bag cause the same problem .try moving the rear bag location an thumb pressure on the stock can cause it or the lack of. The gun has more recoil with the bullet weigh change.When you have tried all that then go to what the bench rest shooter do speed it up or slow it down. Good Shooting Larry

I have a couple savages. I'm just getting a new Dasher barrel up and going for long range target shooting.
On the rear bolt do you run it snug, tight ? Or do I just have to tweak it one way then the other to see what this gun likes?
It is pillar then full bedded with deacon in a heavy BR stockade stock

Tim

 

[BoydAllen]

Put the front one in finger tight, then the rear. Set the rifle on its butt and tighten the front one , and then the rear. Experiment, to see what your rifle likes. I would expect that you probably will nee some sort of right angle ratchet to get to the level of tightness that a pillar allows, since you can't get there with a screwdriver type of handle. I would probably get an inexpensive inch pound torque wrench from Harbor Freight to work with. I have spent enough time doing mechanical work, like engine building, to respect the idea of having a way to measure tightness, and, over the years, I have developed a pretty good feel for what small fasteners are telling me as they are tightened. If you lack that experience, it is particularly important to have a way to measure what you are doing.

 

[moose1223]

Progress Report
I put the gun on sand bags in hopes of minimising any anomalies from the bi pod setup.
We found that the gun is very sensitive to load but more so to case capacity. If the case weight is exactly the same (within .02 grains) we lose almost all vertical. The more we push it, the better the horizontal and the vertical gets worse. There seems to be almost nothing in between a clover leaf shaped 3/4 inch group and a perfectly straight vertical line 1 inch.
All testing was at 250 yards, no wind, and no mirage.