Help load development

[sveltri]

I am almost at my wits end with load development on my gun. Almost regardless of powder, charge, seating depth, and bench support I consistently shoot two touching (or very close and 1 out of the group. Most of them are MOA or sub, but this is driving me nuts. I have been bow hunting for the last 10 years and really only shot a few rounds before season (if I had a rifle tag) and then went hunting. I've killed everything I've shot for the last 10 with a gun. The first two pics below are 59.05 H1000 at likely 6 different seating depths, being new to reloading I was trying to test seating depth based on COAL (I've learned the errors of ways now), the bottom left is 59.5 H1000, middle is 60 H1000, the right is 56.5 RL26 all seated at the same depth. All groups are shot with 156 Berger's gun is a Savage UL 6.5 PRC. I know without a doubt some of this is me, but I doubt I'm exactly 66% right 100% of the time. Any thoughts, suggestions, or questions to help me figure this out?

 

[sierracharlie338]

Pic didn't attach correctly that I can see

Is this a factory barrel or aftermarket?

 

[Maol]

I am almost at my wits end with load development on my gun. Almost regardless of powder, charge, seating depth, and bench support I consistently shoot two touching (or very close and 1 out of the group. Most of them are MOA or sub, but this is driving me nuts. I have been bow hunting for the last 10 years and really only shot a few rounds before season (if I had a rifle tag) and then went hunting. I've killed everything I've shot for the last 10 with a gun. The first two pics below are 59.05 H1000 at likely 6 different seating depths, being new to reloading I was trying to test seating depth based on COAL (I've learned the errors of ways now), the bottom left is 59.5 H1000, middle is 60 H1000, the right is 56.5 RL26 all seated at the same depth. All groups are shot with 156 Berger's gun is a Savage UL 6.5 PRC. I know without a doubt some of this is me, but I doubt I'm exactly 66% right 100% of the time. Any thoughts, suggestions, or questions to help me figure this out?

Can't see the photo. Is always the 3rd shot?

 

[sveltri]

 

[Rick Richard]

If that is a factory barrel, then that maybe all you will get out of it. Make sure you let it completely cool between shots since that looks like a typical pattern with skinny barrels and not allowing to cool between shots. Have you tried 140s?

 

[sveltri]

Can't see the photo. Is always the 3rd shot?

No it isn't. Should be able to see it now.

 

[sveltri]

If that is a factory barrel, then that maybe all you will get out of it. Make sure you let it completely cool between shots since that looks like a typical pattern with skinny barrels and not allowing to cool between shots. Have you tried 140s?

It is a factory Proof barrel. I typically give it at least a couple minutes between to allow some cool down.

 

[sedancowboy]

There are several threads about this on LRH. It is almost always something loose and moving such as scope mounts or action screws need torquing or the action is shifting in the stock.

 

[sveltri]

We've torqued the action screws and scope screws. I think it's something I'm doing but cannot figure it out.

 

[Taco John]

It is a factory Proof barrel. I typically give it at least a couple minutes between to allow some cool down.

You are not alone.

I bought a new proof cfw barrel here for a 308 win.

It hates every normal 308 load you can think of.

Stumbled onto Speer grand slams @ 2900 fps w/ varget. Those it will shoot one hole.

I put it together for a friend, but I've never wanted to pull my hair out more.




A .308 win should eat just about every thing you feed it.

It's maddening.

 

[Shane Lindsey]

Try getting aggressive with seating depth. I have tightened the flyer up by this. Worth a shot.

From current. Try .050", .070", .090" deeper.

If any show promise take the best and work .003", 006",.009" in each direction.

May need to lower your charge weight first.

 

[Hugnot]

Looks like my last adventure with my 6mm-06. In my case I quit using the loads that produced fliers, pulled bullets and retreated back to my laboratory, verified the twist,. I then elected another bullet that was optimum for my barrel twist and started about 1.5 grains below estimated max (it's that wildcat thing) and worked my way up in .5 grain increments bullet seated .05 down. I got a good handle on the problem and will finalize tune up next time. I take it that the rifle is a 6.5 PRC, those 156 grain 6.5 bullets must be real long & pointy. I shoved a cleaning rod having a tight patch on jag, down bore about 1 foot, wrapped masking tape on rod, marked tape with felt tip pen, lined up tape with receiver ring and slowly pulled rod out and stopped & measured upon 1 complete revolution - sure enough an 8 twist - just like the nice gun smith crew was directed. I also checked, neck tension, bullet run-out and trim length. I also measured my bullet lengths.

Twist Rate Stability Calculator

Our newly updated Twist Rate Stability Calculator not only tells you what your SG is, but it also lets you know if you are reaching your optimized BC.

bergerbullets.com

This might help. An 8 twist gives "marginal stability" as per Berger Sg analysis. I don't have a clue of what the twist rate for your rifle is. Should shoot 140's beautiful.

 

[nwmnbowhunter]

Clean, tighten everything down good and make sure nothing is binding. Try a known good scope from another rifle.

When I have ever felt like I'm chasing my tail it has usually been the scope.

Don't force something you want... give the gun what it tells you it likes.

Also how heavy is your trigger pull? Shouldn't be more than 2.5 pounds or else you'll end up with groups exactly like yours.

Don't get frustrated... just use it as a learning experience.

 

[Gamesniper19]

So some PROOF barrels are subject to POI shift. What puzzles me is that although the POI shift MOA is similar, the position of the POI shift is different. As a guide, lateral POI shift is usually the rifle and vertical POI dispersion is usually the shooter.
I would shoot a few groups and let the barrel completely go cold between the groups. That may mean 5 mins between shots. If you do this and you shoot a consistent group, it is likely a heat induced POI shift from the barrel. If that is the case, save all your photos and experiment data and call PROOF and see if they will send you a new barrel