Key Holes

[dschliem]

I have a 3 year old Border barrel on my Rem 37. My group sizes are a lot worse than when it was new. I'm lucky to hold a .500 group at 50 yards. The people who score my targeta say it looks like some shots are keyholeing. I have set the tuner to Eley Black box ammo. It seems to like it. My question is, what other things beside an oversized bore can cause this condition. If it is strictly the barrel I will replace it, but before I do I would like to know if anyone else had this condition and cured it without replaceing the barrel. I thank you all for any feed back you can tell me.....Slim

[Fred J]

Slim:
Have you tried another brand od ammo?
What does the bore look like?

[cpeters]

What kind of temperatures have you been shooting in and have you measured the actual twist? They are not always what they are supposed to be.

Charlie

[ProneShooter]

If it is a 17.5 tight-bore barrel it will not shoot Eley in temps below 60 degrees. I have 2 of them ( both on 1813 actions) and they shoot great when it is warm and horrible in the cold.

[obx22]

Check the crown, hidden by the tuner, you could have any number of issues.
Bullet speed, twist rate, and density altitude could all work together to cause a keyhole as well.
Take care,
warren

[Kent Owens]

What is the lot# of the ammo? Some of the 1006-!@#$ and 1077 prefix stuff keyholed bad while the newer Eley lots do not do it, in the same guns.
I shot 17.7 twist barrels last year and had no keyhole problems at temps down to 40 Degrees.

[dschliem]

I want to thank everyone that sent in a reply, Fred J., CPeters, ProneShooter, OBX22, and Kent Owens. There are several things I'm going to look at. The temperature out here is what you get. The ammo is not of the lots mentioned, Yes, I have tried other ammo, very little change, my twist rate is 16 to 1, I am going to have the barrel recrowned. It may be what is effecting the performance of the rifle. If the condition clears up, I will let you know.......Slim