strange problem with load development...

T

tpbscha

Beginner
Dec 19, 2006
50
0
I have a Hart-built 25/300WSM and I keep getting 2 distinct groups on paper. The groups are typically 1" - 1.5" apart. Checked scope mounting and that is all tight. This is a Howa action/#4 Hart barrel/4.5-14x44 Zeiss. The stock is a B&C Sub-MOA. Think it could be a bedding issue? Shooting 110 AB w/ IMR 7828, MagPro, and RL22.

Thanks!
 
From what you wrote, sounds like your components are top notch. However there are a fair amount of varibles that can cause that issue.

Some of the things I have experienced that come to mind:

Does this rifle have a good track record and it just went south?
Have you removed the barreled action from the stock and reinstalled, while watching for stock flex?
Hows your trigger?
Are you typically getting the spread with all loadings?
What is your shooting rest and technique?
Consider a faster powder, the ones you list are a tish to slow for me.

It is hard to troubleshot an issue from behind a keyboard, but the above are some of the things that come to mind for me. I am sure more folks will jump in with their experiences and sugestions.

Good luck and keep us in the loop..

Rod
 
Thx for the reply. This is a new rifle that I have just started working with. Shooting from the bench and doing 1/2moa with other rifles. I have worked the factory trigger and it is fair. May go ahead and get a Timney. I am going to bed the stock tonight and see if that makes a difference. I have some RL19 and IMR4350 that I may try also. I usually load 4 rounds for load testing. It will put 2 in one big hole then the other 2 go in another hole 1" away.
 
Double grouping = mounts/scope issue or bedding 95% of the time.
 
Is it the first two in one hole, then the second two in the second hole, or are they mixed up? It could be related to barrel temp, which would indicate a bedding issue in the barrel channel.
 
I allow 4-5 minutes between shots. There is no barrel contact past the shank. The shots move randomly. Shots 1 & 2 may go together or it may be shots 1 & 3 or 1 & 4. End result is almost always 2 here and 2 there and always in the same relationship to each other.

Hopefully bedding will take care of it...
 
What kind of rest are you using? I would double check to make sure there are no variable at the bench.
 
PoP's probably right. That's where I would start. Mount, free float, bedding.
Also, are you using a Magnum Primer?
 
Four or five minutes between shots? :shock:

That's a very long time. Both benchrest and highpower prone shooters put 'em downrange much faster than that in competition, to take advantage of conditions being "right" and stable. I don't know what the conditions are like in your area, but 4 shots spread out over 20 minutes here would see rather different wind conditions normally, leading to different points of impact.

I see the BR guys getting all five of their rounds downrange in a minute or two, and us NRA "highpower" prone shooters usually take a little longer because the target is pulled, scored and marked between each shot. Typically around 10 minutes for all 20 shots in their required strong of fire. Twenty minutes is allowed for 'em, but they rarely take it. The speed with which BR guys fire when their conditions are "right" amazed me.

Much better to get 'er done!

Just mentioning this as conditions play a huge role in what the group looks like downrange. More so than many of us give credit for.

Just a thought. Guy
 
I am using Mag primers (WLRM). Whenever I can find some std primers I intend to try that too. Velocities were ~3430-3500 and SD was 12-31 with the various loads.

I guess 4-5 minutes may be excessive, but I had plenty of time and would rather not smoke the barrel too soon! :roll:

Conditions were perfect yesterday evening and I was able to shoot 1/2moa @ 200yds with another rifle. My rest is similar to a lead-sled kinda gadget.
 
I had a very similar condition with a new 257 Wby MkV. I had it re-bedded and re stocked it and tried every kind of loading variation. two groups. .5 in. but 3 " away from each other. I could shoot 20 shots and they would be in one or the othe group. I traded the gun. I kept the scope. 15 yrs. later I put the scope on a rifle that was a known tack driver. Same problem split groups. The scope was defective. I don't know if the mounts were out of align and torqued the scope or it was just defective but something internal was loose and shifting. So what was said by others about loose mounts or a bad scope may be it. Most bedding problems result from a hot barrel touching the stock and the group strings further and further in the same direction. It doesn' bounce back and fourth to the exact same spots. Try removing the scope and checking the mounts and rings for tightness and temporarily put some other scope on the rifle and see if that fixes it. I didn't find out about trueing the scope rings untill later but I've read that scopes can be torqued pretty easily and cause problems due to fairly minor mis-alignment.
Good Luck
Elkhunt
 
Greg, have to disagree about the bedding. Having run into the exact problem we are discussing more than once. Bad scope once, skim bedded the other and the groups came together.Rick.
 
Rick, Greg, Either one of you guys could be right. The only reason I didn't suspect the scope, was I saw who made it. If it has said bushnell, tasco, simmons ect, the scope would of been much higher on my list. I'm just not aware of many problems with Zeiss scopes.
 
No matter the maker, a scope can be the problem. Parallex gives many shooters problems and they are not aware it exists. I don't expect a quality scope to give problems but it does happen.Rick.
 
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