i have a B78 i 22-250 that likes to double group anyone have any ideas on the matter,perhaps magnum primers?

What do you mean by double grouping? How many shots fired? High or low? Right or left?

Can be:

scope or base loose
bad scope
bbl-to-receiver mating
powder position
loose buttstock
forearm bedding
shooter-&-rest technique

...and a host of other possibilities.
Regards, Joe

a b78 is a single shot rifle - try only loading 1 round at a time

quote:

Originally posted by butchloc:
a b78 is a single shot rifle - try only loading 1 round at a time

quote:

Originally posted by butchloc:
a b78 is a single shot rifle - try only loading 1 round at a time

Yeh, and that test stuff our Uncle Sam loaded with two bullets (one cupped into the base of he other) doesn't give very good target results either. Use commercial ammo, not surplus....

Need pics of several targets showing the double groups!

thanks for the info,took all the above into consideration,just wondering if someone else had the same problem,the rifle will print 3 in one hole then 2 in one hole but about an inch or so apart any possible cures other than a new gun

Strictly a guess, but I'm with J.D. as far as forearm bedding goes. It seem that heat expansion or some such triggers a change of pressure point/ amount. You need to go through a process of elimantion, one item a a time until to find the cause. FWIW --- John303.

quote:

Originally posted by rockchuck3006:
thanks for the info,took all the above into consideration,just wondering if someone else had the same problem,the rifle will print 3 in one hole then 2 in one hole but about an inch or so apart any possible cures other than a new gun

Been awhile since checked back on this thread.

And the answer is yes I did have one that shot 2 groups - That's why I asked to see a target.

From your description above, your rifle is not double grouping like mine was. Mine would shoot 2 groups, alternating shots between the 2 groups.

I had a similar problem. Could be the same problem. Out of a series of five shots, same handload, three would produce a good group, and two would produce another good group. I don't remember in what order fired in relation to which group. I don't think it matters anyway.

This is a new custom Encore barrel and I have been using new brass, factory primed. After shooting a batch of 50 one time, and the two group syndrome was rather consistant through all those, I meanwhile decided to order a neck sizer. I tried it with maybe 15 or 20 shots, and so far it has stopped producing the two groups. More testing will affirm.

I'm pretty sure I'll have to partial FL size in the future, since the brass is pretty tight on closing the breach. But for accuracy testing, I wanted it snug against the shoulder.

Sure, all those things mentioned in above posts MAY cause this issue, but if you are like me, you have already checked those things and it comes down to the notion that it's one thing that's causing the problem. Just discovering what is by a process of elimination. I had a hunch that somehow the fireformed brass may align the cartridge better in the chamber. Just a hunch, and in some ways it doesn't make complete sense. After all, if the factory brass caused the problem, looks like it would be random spread rather than two groups.

Anyway, I changed powder to Varget, changed bullets to lighter weight, neck sized, and worked up to the max per book load. Maybe a combo helped. Anyway, it was pleasing to get five shot groups all together in about 1". Hopefully if I can do it twice, I can keep doing it.

KB

FWIW, I had the same problem with a Ruger RSM in .375H&H. It was throwing alternating shots into the two groups with every commercial load and first handload. 2.5" to 4".

Folks encouraged me to check that scope internals weren't damaged. Swapped to known good scopes and had the same problem. Other culprit folks mentioned was it could be bedding. I didn't fix this because at that point I hadn't bedded a stock, and I loved the wood on the gun and didn't want to screw it up or send it to Ruger and have them change it out.

I switched from Rel15 to 760. The second handload threw the two patterns all into 3/4". Still, two distinct "groups" with all bullet holes touching.

HTH,
Steve

i have a B78 in 45-70 that does the same, the first 3 are dead center and if the barrel is warm the next go 1" high and left. once the barrel is cool they go back to center.