M1 carbine key hole

[sixpointfive]

I have an M! carbine that shoots 1" groups perfect at 25 yards using jacketed bullets. When I went to shoot my 130 Lyman 311410 sized .309 with 12gr of H110 they key holed on target. What is going on here, please help.

[KCSO]

Size it to 311 or so and give it a try.

[MtGun44]

+1 on larger diameter. Have you slugged the barrel? You want to be at least .002 over
groove diameter with rifles in my experience.

Bill

[Le Loup Solitaire]

Hi and welcome to the forum. Your cast bullet is not fat enough and is not getting a good grip on the rifling in the bore. It needs to do that to get the full amount of spin. If undersize it also can and usually does, tilt on its own long(itudinal) axis and comes out of the muzzle tilted...and then goes downrange with a wobble. The result is oval/egg shaped holes in the target. Sizing to .309 or .310 should improve/fix the problem. LLS

[Shiloh]

I've yet to see a .30 cal. boolit shoot well sized at .308.
+1 to above posts. I'd try .310

Shiloh

[beagle]

I'll second the .310". Mine shoots well at .310"./beagle

[sixpointfive]

Thanks Gents, loaded the bullets at "as dropped" dia .310/.311 and the key hole problem disapeared. Rifle is shooting great lesson learned.