Keyholing

R

robhic

New member
I shot some lead bullets from my Glock G19 yesterday using an aftermarket LoneWolf SS barrel. My 9mm 147 gr lead, flat nose bullets from T&B shot well . They were loaded over 4.8gr of AA#5 powder. (specs from load-book)

I also had some same bullets over 4.7 gr of HS6 per same book - max was 5.0gr. It looked like I was grouping MUCH better than I would expect. Brought the paper B-17 bullseye target in (indoor range) and the "groups" turned out to be wide tears in the paper. Looked to me like keyholing and NOT Seal Team 6 accuracy. :(

Barrel was NOT leaded or fouled in any way (only shot 59 rounds) so I was surprised. Only keyholing ever experienced was cheap ammo in .22 pistols. Any ideas/thoughts on what could produce keyholing in 9mm lead from a clean barrel and (seemingly...) hot enough load? I was gonna load a few at 4.8 gr of HS6 and go up until I hit 5.0 gr to see if speed helped. Thanks!
 
what kind of target backing did you have? if you don't have the targets up against a solid backing the bullets will tear part of the target
 
what kind of target backing did you have? if you don't have the targets up against a solid backing the bullets will tear part of the target
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No backing. The "tagboard" (heavier than paper) targets are clothespinned to a bar across a hanger so the target is suspended. I've shot here (exclusively) for years without this issue. I don't suspect the targets, especially since the same rounds loaded with AA#5 (and all other bullets ever shot here) were OK.
 
I've only had one firearm keyhole. A Sig P238 will keyhole on me occassionally. A stronger grip and clean barrel cured it.
 
I would have to guess the barrel is large and the bullets small.

If its true key holing. I would back it up with heavy cardboard and see.

Only way I know you can get keyhole is a mis fit bullet/barrel worn out.

I had not heard of it in a grip situation, so a bit ???? on that.
 
? who is T&B?

I've seen 147 cast FN bullets tumble before, and was not able to determine the cause. Changed brands and the tumbling stopped ? ? ?
 
Look under good light for marks on the paper left by the lead itself. It'll be dark on white paper and slightly shiny on black. If the marks are oblong when you press the tears flat, then you have keyholing. If the black marks are round, then you have some bad target paper that is tearing. Spray-gluing a target to some corrugated cardboard will confirm it one way or the other.

There are several causes of keyholing. The worst I've seen in .22 rimfire and in .357 Magnum both had the same cause. The rifling in the barrel was defective, causing it to be about three times taller on one side at the muzzle than at the other.

A twist rate too slow for the length of the bullet will cause it. You might double-check the rate Lone Wolf uses, though this is a less common issue in handguns than in rifles. Check anyway. If shorter bullets shoot fine, it's a candidate.

Bullet distortion from undersized lead bullets will do this, but gas blow-by is normally accompanied by severe leading, and you said you had none, so I doubt this is the cause.
 
I had keyholing a while back with some handloads I made for my 10mm Glock 20. I am using a Lone Wolf barrel of 5.25" in this gun.

I bought some Extreme 200 grain plated bullets on sale a year or two ago and loaded them over some LONGSHOT at around 1200 fps.

They keyholed like crazy. You should have seen the target LOL.

I still have 400 hundred of them under the bench. I'll drop them into some 40 S&W some time and burn em up a little slower. My guess: they can't handle the velocity. I'm not a fan of Extreme bullets anymore. I shot a thousand 180 grain and accuracy was terrible. I use Rainier HP now and they are excellent even at higher velocities.

;)
 
I would have to guess the barrel is large and the bullets small.

Only way I know you can get keyhole is a mis fit bullet/barrel worn out.
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What rules that out is that barrel, while not having more than maybe 200 rounds through, it doesn't have wear and all other bullet-types shot without incident. Just these and ones loaded same except different powder were OK, too...:confused:
 
? who is T&B?

I've seen 147 cast FN bullets tumble before, and was not able to determine the cause. Changed brands and the tumbling stopped ? ? ?
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T&B Bullets - https://tbbullets.com/ Now you make me wonder if something different in loading because that exact same bullet in an exact same load except powder type has had no problems previously. This is my first time using 147gr bullets. I normally load 115 and 124-5 in 9mm so bullet weight and lighter powder load might be relevant.
 
Look under good light for marks on the paper left by the lead itself. It'll be dark on white paper and slightly shiny on black. If the marks are oblong when you press the tears flat, then you have keyholing. If the black marks are round, then you have some bad target paper that is tearing. Spray-gluing a target to some corrugated cardboard will confirm it one way or the other.

There are several causes of keyholing. The worst I've seen in .22 rimfire and in .357 Magnum both had the same cause. The rifling in the barrel was defective, causing it to be about three times taller on one side at the muzzle than at the other.

A twist rate too slow for the length of the bullet will cause it. You might double-check the rate Lone Wolf uses, though this is a less common issue in handguns than in rifles. Check anyway. If shorter bullets shoot fine, it's a candidate.
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I'll have to pay more attention to the target post-shooting. When I saw (what I felt was) keyholing I just tossed them. I, too had headaches with .22's but that was all until this recent issue. The SS barrel is, essentially, brand new. I use it to shoot bare lead and probably just a couple hundred rounds. It didn't have a mark in it after getting home the other day. Didn't even look like it had been used for 59 rounds.

The barrel and/or twist rate could be an issue except for the fact that all other bare lead bullets (115, 124-5 and these same 147's) never gave a problem.

As I said above, the exact same bullet using different powder(s) didn't keyhole. I had 50 rounds of the 147gr lead flat nose using AA#5 and all shot fine. I reloaded the mags with the same bullet except using HS-6. That's when the keyholes appeared.

I read that a slower powder would give higher velocity. The AA#5 loads were reasonably mild but ran well. I shot same loaded over W123 and those were mild, also. So I thought I'd use the slower HS-6 to see if they seemed hotter.

In all honesty I really didn't notice a difference in recoil or anything. I'm gonna load some more and go from the 4.7gr up 4.8, 4.9 with 5.0 being the book max. I'll not do that (probably...;) ) but see if hotter loads make a difference.
 
robhic said:
T&B Bullets - https://tbbullets.com/ Now you make me wonder if something different in loading because that exact same bullet in an exact same load except powder type has had no problems previously. This is my first time using 147gr bullets. I normally load 115 and 124-5 in 9mm so bullet weight and lighter powder load might be relevant.
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In the exact same barrel?
 
robhic wrote:
They were loaded over 4.8gr of AA#5 powder. (specs from load-book) I also had some same bullets over 4.7 gr of HS6 per same book - max was 5.0gr.
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Were these loads properly developed by beginning with the starting load per the manual and then working up in increments of 0.1 or 0.2 grains? Or did you just look in the book, pick something less than max and decide to start there?

The reason I ask - and the reason that following proper load development techniques is important - is that if you began with the starting load, was there any indication of instability with the increment that preceded the 4.7 gr HS-6 loads?

If the 4.7 gr HS-6 load was not the latest increment in a properly developed load then all I can say is that some powders work better than others in certain loads in certain guns.
 
I should have thought to mention that just as the off-axis rifling can cause a bullet to unbalance enough to keyhole severely, so can internal imbalance. External balance causes like an out-of-square base or an SWC ogive that is off center are relatively easy to identify. But if you have a normal looking set of bullets that misbehave this way when others the same weight and length do not, it is probably worth taking a bandsaw and sectioning a few of them to look for a core that is cast with gaps or dross inclusions, or to look for very unevenly thick copper plating. Either could produce the same effect as the rifling problem.

However, given the AA#5 history, none of that applies here. I guess I didn't quite get what was going on from the original post. I'm going to guess that either a lot of the HS-6 is not getting burned and is blasting against the bullet base as it exits, in which case a magnum primer might fix the issue. The other may be that it is burning just fine and holding barrel pressure up too high for the hardness of the bullet, so the base becomes upset by the high pressure muzzle blast as it exits. You can test the latter theory if you know someone with a 9 mm carbine. The higher expansion ratio of the carbine will let the muzzle pressure drop to a lower value by the time the bullet leaves.

The old F.W. Mann book, The Bullet's Flight… has a lot of pictures of bullets he intentionally put into barrels that were too short so that the muzzle pressure was high and the profiles look like a badminton shuttlecocks, they are blown out so badly.
 
A keyhole typically appears as a side on bullet shape, not a tear in the paper. Keyholing is caused by undersized bullets, an oversized barrel(unlikely here), a lack of lube and sometimes too low velocity(also unlikely in this case).
I think you're just seeing the target paper's low grade and if the target is just hanging on a clothes pin or the like it might be moving upon impact. And causing tearing. Mind you, FP's aren't made for cutting nice round holes either.
Neither HS 6 nor AA #5 require a magnum primer.
 
The only thing that I wonder that hasn't been discussed is lead hardness. Was it so soft that they stripped, or too hard?

Those two loads will be nearly identical, hs6 worked well for me. This will sound crazy, but slug your barrel and send it to wolf, maybe.
 
In the exact same barrel?
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Yep, the one and only LoneWolf SS barrel for 9mm Glock. I've shot other rounds (115, 124-5 plus some of these 147s) and only difference was the powder used.

All right above minimum and gave no problems until the HS-6 was used. That's why I am baffled by this. AND .... yes, the barrel was clean as in no marks from the 59 bullets I fired through it.
 
Unless you have access to a chronograph, I don't know any easy way to take the diagnosis much further. Look carefully at the targets on the next go-around. If you are simply getting tearing and no true keyholing, based on the bullet marks, it almost certainly means the HS-6 load is producing significantly less velocity than the AA#5 load is. That leads to looking at poor ignition. In un-backed paper, even tagboard, fast bullets cut holes, slow bullets start tears.
 
I should have thought to mention that just as the off-axis rifling can cause a bullet to unbalance enough to keyhole severely, so can internal imbalance. External balance causes like an out-of-square base or an SWC ogive that is off center are relatively easy to identify. But if you have a normal looking set of bullets that misbehave this way when others the same weight and length do not, it is probably worth taking a bandsaw and sectioning a few of them to look for a core that is cast with gaps or dross inclusions, or to look for very unevenly thick copper plating. Either could produce the same effect as the rifling problem.

However, given the AA#5 history, none of that applies here. I guess I didn't quite get what was going on from the original post. I'm going to guess that either a lot of the HS-6 is not getting burned and is blasting against the bullet base as it exits, in which case a magnum primer might fix the issue.
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OK, this is probably the 4th batch of these bullets I used. I loaded all the same with Bullseye, Universal, AA#5 and HS-6 the last two during the same range trip. All were loaded about 2 steps up from minimum with a good bit of "headroom" above to the maximum. Bullets identical except for different powders.

I liked the first bunch enough that I ordered more (see above post where T&B sent some extra) and loaded the rest of the 100 lead flat-nose 147gr bullets. I think it says they are BHH 15 or so.

Maybe I'll load more going lower instead of higher OR try the magnum primer as you suggest. Thanks to all.
 
If, as my last post describes, it turns out you just have tearing and not keyholing, then more powder would be the solution, as the velocity is too low. So you may want to keep an open mind about that possibility. As a sort of general rule, the slower burning the powder, the nearer to maximum load it has to be to burn efficiently and without erratic ignition.

For completeness I should mention the magnum primer could also make things worse by unseating the bullet before the powder starts burning well. Only trying it will tell which way that will go for you. A chronograph showing larger velocity SD would also be an indicator of erratic ignition.
 
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