Shrinking the Group

[varmintseeker]

I'm shooting a md 77 mark II 22-250 with a 8.5x25x50 30mm VX3. Bullets loaded are the 50 gr Z-MAX. Powder used was 4895. Started with 35gr and went forward .2 at a time to 35.4 and backwards to 34.8. Best group was with 34.8. C.O.L is as stated in the book at 2.350. Now to try and shrink the group more I would appreciate hearing some suggestions. Do I increase C.O.A.L .010 at a time or what. I know that there are a lot of varget guys out there and XBR guys, but powder is hard to find now so I use what I have. Barrel twist is 14. Thanks


100 yard target 4 shots 34.8grs 4895

 

[RT2506]

Most of the suggested COAL in the manuals are waaaaaaaaaaay off the lands. This is just a COAL that will work in most any rifle. I would load 5 rounds 10 thousands and 5 rounds 20 thousands off the lands or the longest you can that will still work through your magazine and give it a try. I have found that many bullets shoot best someplace between 10 and 20 thousands off the lands for me.

 

[westcliffe01]

The Hodgdon website Cartridge Loads - Hodgdon Reloading Data Center - data.hodgdon.com lists min load at 33.5 to 36.5gr max. So you started somewhere in the middle and have not gone near the limit yet.

You do not mention what group size you got, what kind of barrel you have (sporter or varmint) or how long it is nor how many rounds it had down the pipe.

Unless I am mistaken, the Z max is almost the same as the V max except for the color of the tip. With a 1:14 twist you may want to shoot those a bit hotter to stabilize them better. I would not stop until I got the first pressure signs, then compare if there is an optimum point close to max load.

If this rifle has some miles on it, you might want to have the bore and particularly the throat inspected. The throat is the first area to go and then the shorter bullets will shoot badly. With a 1:14 twist you can't really go to longer bullets anyhow. The 22-250 is fairly notorious for burning out barrels particularly if you shoot it a lot. If it is new, then by all means try seating a few really long, chamber and re-check the overall length, it will get you close if you don't have a gauge. If the throat is worn you may never find that point...

 

[Mikecr]

More or less in agreement with both, I would stop where you're at and use Berger's seating testing method to dial in best seating. Then move as you have further upward in powder until reaching pressure issues & see if something looks better.

A chosen book length could be the very worst place to be.

 

[varmintseeker]

The gun has had 875 rounds through it. It has a 25 inch heavy barrel. As far as COL I was going by the hornady edition 8 manual and max powder was 35.4gr of 4895. I tried to post a pic of the target here, didn't work. I will try again[A.TTACH][/ATTACH]22312​

 

[varmintseeker]

I would also add that the Bore has been looked at with a bore scope and other that a real slight carbon ring it appeared to be in excellant shape. Thanks for any and all suggestions.

 

[benchracer]

I agree with Mikecr. Try the instructions on the Berger website for finding your optimum seating depth:

Getting the Best Precision and Accuracy from VLD bullets in Your Rifle | Berger Bullets

I have found these instructions to work even with non-VLD type bullets.

Once you have found your optimum seating depth, follow these instructions for your powder charge run up:

OCW Overview - Dan Newberry's OCW Load Development System

This will get you to the max accuracy potential of your rifle and do so in a minimum number of rounds.

One note on seating depth with your 22-250: As others have mentioned, you probably won't be able to seat your bullet out far enough to touch the rifling. In that case, seat it out as far as you can, while leaving enough bullet in the case neck for the bullet to remain securely seated. Shorten your seating depth from there in accordance with Berger's instructions.

 

[varmintseeker]

Played with the powder a little more. This last group was with 34.9grs. of 4895. If I measured right it's .221. Should I leave well enough alone or play with the seating lenght now. It's still at 2.350 now

 

[benchracer]

If that group is at 100 yards or more, I would stop tinkering, load some ammo, and go shoot something!

 

[varmintseeker]

That's my plan. As soon as I get off work I'm headed home to load a few of these rounds then it's off to the river bottoms, Hopefully for some yotes. Thanks for your help. Dave

 

[varmintseeker]

Also that was at 100 yards.