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Posted - 02/15/2004 : 7:28:08 PM
I finally got out to shoot my M91/28 TS carbine. I used the new Hornady .268 160gr RN 6.5 Carcano rounds. At 50 yds, the best I could do was a 4 1/2" group with several fliers. All of the rounds keyholed.

Would counterboring the muzzle help with accuracy and the keyholing problem?

Posted - 02/15/2004 : 10:08:14 PM
If all the rounds keyholed, something is wrong. First, are you sure you have an M91/28 and not an M91/24? The 24s have a cut-down M91 long rifle barrel with gain-twist rifling; there is not enough spin imparted to the bullet in 17 inches of barrel for stability. Second, what kind of condition is the bore? I would think it must be pretty bad to keyhole bullets in a 91/28. Third, what does the barrel crown look like? A really bad burr might cause what you describe. And finally, what load were you using? My favorite short-barreled Carcano load is 33 grains of IMR 4064 under the Hornady .268 bullet seated just deep enough so the round fits the magazine. I get groups of 2-2 1/2 inches at 100 yards from the bench with a Moschetto Cav.

Give us a little more info, and I'll bet somebody here can figure things out.

Posted - 02/15/2004 : 10:42:32 PM
It's a 91/28 with the small adjustable rear sight. The rifling looks well used but still shined up OK. I was using Hornady commercially loaded 6.5 Carcano with 160gr RN .268 bullet. The crown looks good (no dings) but the rifling is very thin at the crown.

I don't know if it's worn out or if counterboring would help it. I bought the best ammo available for it (not Prvi Partisan). Any suggestions would be appreciated.

Posted - 02/16/2004 : 5:21:04 PM
This is the first time of hear of this problem with Hornady ammo. I know during development the bullet was tested with fairly good results in a 91/24.

Stupid question: are you sure you do not have a 7.35mm carbine? That would not fit with the adjustable sight, but I wanted to ask anyway. Did you buy the box from a reputable dealer, or was some sort of gunshow table deal?

1) slug the bore
2) measure the diameter of the bullet
3) inspect carefully the bore to see if there is any bulging or other rifling problems that could damage the jacket
4) check spent cases for signs of pressure

If the abobe yelds nothing noteworthy, contact Hornady for clarifications, possibly offer to send in a sample for refund and for investigation if the cartridge meets specs.

Posted - 02/17/2004 : 6:41:39 PM
Definitely a problem somewhere. DMALA post probably contains the answer to your problem. Good luck.

Posted - 04/06/2004 : 4:10:20 PM
UPDATE: I finally got it out to the range after being counterbored and now the holes are ROUND! It seems to have worked.
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