SmallCaliberCentral

I have something I can not figure out. My stevens 200 I turned into a mod 12fv has a wierd problem, and I need help. This thing shoots like a house of fire, most grouping in the .2 to .3 area. But every once and a while It lets loose a keyhole round. I thought it was bullets,It did the same thing with diferent bullets. The thing shot great with 32 g seirra bks then one day it keyhold a bunch of them. So I tried 39 gr seirra bks shoot great till tody let two key hole rounds out of 60 rounds fired. It shoots dog towns good never had a key hole yet with them, but dont grounp like the Seirra's. It will key hole like crazzy with hornady factory ammo. It shoot hornady 40's ok something like a .7 group, never had a key hole with them.

The crown looks fine. I have no idea. Hopefully someone can help me out. further info the barrel I got new, The barrel has 304 rounds down the tube. Never been hot.

Thanks Pat

Welcome to 32 & 39 Sierra's in the Savage barrel. Mine does the same thing.

The bearing surface on the Sierra's is quite a bit longer than VMax's. So, I use the Hornady's in mine.

The problem gets worse as your barrel dirties as well.

acloco wrote:
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The problem gets worse as your barrel dirties as well.

Yes, I would also suggest looking for copper in the bore.

Are the keyholes latter in your shooting or do you get them from the get go?

They are sporadic, may get one from the get go may not; may get one after firing 20 rounds have a keyhole and after that fire another 20 rounds without one.

My guess is a rough copper deposit. Copper deposits change continuously as you shoot. As the copper builds it could easily become rough than smooth out again, then develop another rough spot, so on so on.

The Sierras have a thin jacket. My theory (no proof at all) is that the lead in the bullet is actually forcing its way to the front of the bullet. Or to put it another way the jacket is lagging behind due to excess friction. This would force the hole in the jacket tip to open allowing the tip to fly out. I developed this strange theory when I began loosing the nylon tips on the 39smk's. Unfired I could not pull out the root of one of those tips with a plier. But I found some relatively perfectly intact nylon tips in the backer board and targets. Actually noticed two holes develop at once. One bullet hole (nasty flyer, no keyhole) and a small keyholed nylon tip.

Keyholing Hornady bullets is rather rare. I think you have some nasty copper hiding somewhere in your bore. Pauls Wipe-Out is the best cure I've found for that.

Try changing to a slightly sootier powder. IMHO R-10X is just to dirty although many have had good luck with it.
I'm using Viht 135 at the moment with 40 Bergs. Great accuracy around 3730 fps. I have shot up to two hundred naked rds without cleaning. Two or three patches of Shooters Choice and two dry and I'm done. No copper at all. No carbon in the throat. Life is good.
H-4895 will turn my bore orange.
Good Luck

I shot about 1000 40gr Vmax's, 2000 Sierra 39 BK's,and about 500 35gr Bergers out of my two Savages. 97% of them were at paper, and "never" had one keyhole. Although I never shot more than 60 rounds without a good cleaning. I would also like to see what the inside of your barrel looks like.

It's easy to compare bearing surface lengths of two different bullets. Just open your calipers to .201 and lock. then put the two bullets in the jaws point first.Line them up 90 degrees to the jaws and wala. It's easy to see where the boat tail starts You'll be surprised what you find Good luck and keep us posted.

Good info already given on the copper fouling which could be causing the problem but my experience puts the problem with a carbon ring just ahead of the chamber. This is much harder to remove then copper and actually "sizes" the bullet down as it passes. A loose bullet doesn't rotate properly and/or will distort. The thinner the jacket the less hard carbon it takes. Factory barrels don't clean easily and carbon is the biggest problem though some will copper foul too. Check this artilce Precision Shooting article on the Hawkeye borescope and cleaning test:

http://www.precisionshooting.com/psm_2006_01_issue.html

Just because your .223's are cleaning up doesn't mean the same routine will do it in a .204R, .199" lands with 25-30grs. of powder down them each shot.