What causes bullets to key hole?

[DWS1117]

I picked up a used model 19-5 2 1/2 over the weekend. Took it to the range for the first time this evening. It's nice shooting gun, accurate for the short barrel, and fun. I used two different targets. One for 38's and the other for 357. The 357 target had a bunch of clean cut holes roughly in the center. The 38 target's holes were also fairly centered but several looked as if the bullet had gone through the paper sideways. They clean cut semicircle at the bottom and at the 12 o'clock the paper was torn in a cone shape. What could cause this and Why with one caliber but not the other?

Ammo used was Monarch (green box from Academy) 158gr SJHP for both 38 and 357.
I did not try any other ammo as this range's ammo is at least 30% higher than anywhere else. I am not paying 29.99+tax for WWB.

 

[DWARREN123]

Bullets not stabilized since the 357 mag rounds were good. Maybe not enough speed or bullets not expanded to the rifling.

 

[XavierBreath]

I would take a close look at the crown.

 

[earplug]

I had A revolver that had A constricted barrel where it was screwed into the frame. It would keyhole bullets.
I betting you need A new barrel.

 

[MCgunner]

I had a M19 that wasn't that accurate with .38s, why I eventually sold it, but it didn't key hole. I think it might be your ammo. Either the bullets are undersized or they're stripping in the rifling or something. Sounds like an ammo problem. Have you tried other .38s? Round nose stuff sux IMHO. Try some hollow base Remingtion 148 grain wadcutters. If it won't shoot THEM without keyholing, then the gun has problems. Either sell it or try to get it rebarreled or something.

 

[Logos]

Shorter barrels mean the bullet has less time in the grooves and so can't stabilize as well as a longer barrel.

So, you can get a keyhole once in a while if other factors are not just perfect.

It was probably mostly the ammunition. It may even have had something to do with the way the target was situated.

Give the barrel a good treatment with Hoppe's or another good cleaner. Let it soak overnight in the barrel and then brush and clean it really well.

Try several kinds of ammo on the same target.

I think you'll find the problem is not a serious one, but if you still have problems, it's trade-in time.

 

[the naked prophet]

I'm not so sure it's keyholing. The way you describe the target holes, it seems like the bullets may just be going slow enough that they aren't "cutting" clean holes so much as "tearing" through the paper.

Do the holes look like a cylinder with one rounded end? Or do they look like a teardrop or upside down ice-cream-cone? The first would be keyholing, and the second would just be a slow bullet tearing the paper.

I have had lots of round nose .38 ammo cut a partial hole but tear the rest of the way through the paper. It was exactly like you described, a clean cut semicircle with a wedge-shaped torn area above it.

Try shooting some semiwadcutters of the same bullet weight and construction, and see if it still happens.

 

[MCgunner]

I'm not so sure it's keyholing. The way you describe the target holes, it seems like the bullets may just be going slow enough that they aren't "cutting" clean holes so much as "tearing" through the paper.

That's very possible. Here again, try some wadcutters.

Shorter barrels mean the bullet has less time in the grooves and so can't stabilize as well as a longer barrel.

No matter how short the barrel is, the bullet will stabilize if things are right with it. Snubbies are quite accurate. I can regularly ring a 15" diameter gong at 100 yards with my Taurus M85 2" .38. The thing is only limited by its short sight radius. I can put five shots into 3" with it at 25 yards off sand bags and there's no keyholing or it wouldn't even hit the target board at that range, much less the gong at 100. What it did do when I first got it was lead the barrel pretty bad with lead bullets which affects accuracy. The barrel apparently was a little rough. Several thousands of rounds later, it shoots good now with lead. The barrel roughness must have lapped itself smooth.

 

[DWS1117]

Or do they look like a teardrop or upside down ice-cream-cone?

Bingo! The gun is not new. It's a 1983 vintage from the info I've received. Accuracy was good. That wasn't a problem. Thanks for the tips. I'll try some different ammo.

 

[MCgunner]

If accuracy was good, it ain't keyholing. When a bullet tumbles, accuracy goes to pot quick, to the point you won't even be hitting the target board. Sounds like you're just tearing paper with round nose bullets.

 

[YosemiteSam357]

I've found that photocopied targets don't cut/tear as well as the "official" NRA certified-type targets on that special brown manila paper. That stuff seems custom made for target use. Come to think of it, it's probably written in a specification somewhere...

-- Sam

 

[Random Discharge]

I used to have a NAA 32 Guardian that keyholed. The rifling was almost non existant in the barrel-my guess as to the problem. It went back to NAA and they remachined the crown - didn't fix it. How does your rifling look?

 

[bill larry]

If accuracy was good, it ain't keyholing. When a bullet tumbles, accuracy goes to pot quick, to the point you won't even be hitting the target board.

Not true all the time.

I have a Colt Model of 1917 .45 revolver that keyholes consistantly. Accuracy is still good, real good in fact. However, the rifling is nearly all gone. Maybe if I put another thousand rounds through it accurcy will begin to fall off. So far that hasn't happened. Its not a range gun.

I know I surely would not want to be on the receiving end of a tumbling .45 round, though. In fact, I kind of like the potential there.

 

[Geno]

In a revolver it can also be a build-up of lead in the forcing cone area. I saw this with my daughter's BearCat. As soon as I cleaned out the lead, it was back to producing good groups.

 

[DWS1117]

Thanks for all the good discussion. It's helping me learn more and more about revolvers.

I believe that the ammo was the culprit. I shot two different types of ammo and the Monarch. The Monarch was the only one that gave the problem. 158gr LSWC hand loads produced nice clean holes pretty much where I wanted them and some factory Winchester 130gr FMJ made nice holes also, although not as accurate as the hand loads.