running a pistol so hot it keyholes

Mr. Friendly

Mr. Friendly

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hey guys. was at the range to day with my Mark III w/5.5" SS Bull. I did run it rather hot today with ammo. but got something unexpected...keyholing?

I put up 5x 4" targets at the 20 yard line. my routine is unloading all 5 of my mags into that 4" target and then counting out how many actually stayed on target. I ran 60 rounds on the first target, then ran another 60 round (after the gun cooled for the few moments it took me to reload...which probably isn't much) on another target, and then 10 rounds on my 3rd, 4th and 5th target. when I checked with my scope, I saw rectangular holes. they were definitely not three shots in a row. we (myself, my shooting buddy and an older competition shooter that was there). he said he'd never seen keyholing in a .22LR pistol before. however, when I told him how many rounds I ran through it straight, he did say that wasn't wise.

anyhow, here are some picture. thoughts?

2z6s0pf.jpg
 
I experienced keyholing with my Ruger Mk III as well a few years back. Thought maybe it was crappy ammo. Took me a week of soaking it in CLP to clean out the bore. Its all good now but something I had never expected.
 
in this instance, it would have been Remington Thunderbolt. There is a slight possibility it was Winchester Wildcat or Federal Auto Match, but pretty sure we were running Thunderbolt at this time.

you can see it was shooting properly on the far left target, which was the first. looks like it started to keyhole or whatever at the end.
 
How does your bore look? Only time ive had keyholing in a rimfire was a pps50 that i put 3 drums of blaser as quickly as possible. At the end it was so leaded up parts of the bore where about 2/3 there original diameter.
 
Any time I've seen .22's keyhole it has been from a thoroughly leaded up bore. Time to clean that barrel out. If you have a scale, see how many grains of lead you peel out of it.

-DF
 
Ammo I was using that was keyholing and eventually fouled my barrel was Winchester XPERT H/V, 36 grains. Now I only use Federal 525 Value Pack ammo and I have not had any problems.
 
I definitely agree with this one regarding non-plated rimfire ammo. Plated Ammo like Federal Bulk, Win 555/525/333/222, Win M22, CCI Mini Mag are my choices of plated ammo. Runs flawless on my rimfire pistols and R597 HB rifle. CCI Blazer is not bad. But Win Wildcat, horrible. What is good on my rimfires my not be a good choice in your rimfires. Buy a box of 50 rds and see what your firearm will like. Plated ammo runs cleaner in your barrel. Some shooter says waxed lead ammo (CCI Blazer) is a bad choice, but I have not seen any problem yet after thousands of rounds. The only inconsistency I have encountered is horrendous misfires with Win Wildcat and fewer misfires with Win 555/525/333/222.

jody_v said:
Ammo I was using that was keyholing and eventually fouled my barrel was Winchester XPERT H/V, 36 grains. Now I only use Federal 525 Value Pack ammo and I have not had any problems.
Click to expand...
 
Had the same issue happen with my Father's H&R 999 and Remington Thunderbolts.

Normally we shoot CCI Mini Mags but we were given a free pack of ~500 thunderbolts that day. After about ~200 to ~300 rounds down range we noticed accuracy issues and weird impacts on the target. 1x50 box later we started to get what looked like keyholing. A quick look down the barrel showed about 1 inch of the rifling at the start was completely smooth due to lead buildup. I don't know if that is the case for you but I figured I'd share haha. (Same ammo caused some cylinder binding in my S&W 17-2 after 100 rounds. I have since given the leftovers away)
 
Remington Thunderbolt and Target are the only .22LR ammo types I have seen that will foul a bore with lead to the point where bullets keyhole.

Generally speaking, Remington does not make very good .22 ammo.
 
As mentioned, most likely caused by leading. Key holing is caused by undersized bullets, an oversized barrel and sometimes excessively low velocity. It's possible that the heat generated melted a bit of each bullet and leaded the barrel to the point the bullet didn't contact the rifling.
 
Happens occasionally to my MKIII. Usually after about 400 - 500 rounds in 1 range trip. When it happens, you can pull out large flakes of lead when cleaning it. Was using CCI blazers the last time it happened (old stock, not manufactured by Federal)

It's most likely because i have 5 mags, and am using one of those McFadden Ultimate Clip loaders :(
 
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