A little keyhole' n trivia.

Last weekend I spent half a day shooting all my revolvers verifying zero, making sure everything was still working properly, trying different loads, firing from field positions, and just general practice; getting ready for deer season. Everything was going as good as it could till I got out my last revolver; Reeder 475 Linebaugh. I'd worked up progressively through the caliber's, starting with 357 and finishing up with the 475.

I shot a few cylinders full of 325 xtp's over a max dose of H110; making sure my red dot was still holding up. I then filled the cylinder with the loads I'll be hunting with: 385 gr Miha cast hollow point over 14.5 gr of HS6. These loads are clocking around 1200 fps.

Now to the trivia..... Once I started shoot the cast loads, my impacts were erratic and with closer inspection, were keyhole'n at 50 yards. Just to let you know, I figured out why, but have never experienced or heard of the reason before. It was a quick fix and things were back to what they were supposed to be.

I would like to here your theories/solutions of what you think it could have been. If no one figures out what it was, I'll give my findings.

It was more than likely the gun. I should probably take it off your hands and do some proper testing with it. Let me know if you need me to help you with this problem.

It was the gun, but quickly got back on track. 😜

I hate you KRal!!! I glanced at your post and went on. Then I had to come back and read it again. I have been going nuts trying to figure it out. And I am definitely not the ballistician in the group....just the most OCD. LOL I was leaning towards something with the load. But, you statement "it was with the gun" pushed me over the edge.

Ok, from my limited experience with keyholing I was using too heavy a bullet for the twist. OR, not having enough velocity to stabilize the bullet. Here is a dumb guess just so I can move on and come back later.
1)You had too much copper fowling. Bullet could not grip lands and grooves to stabilize.
2) you were supposed to put gas checks on but forgot.

REALLY bad flinch?

Since you said it was the gun, was the base pin not locked securely resulting in a loose cylinder causing the issue? Best guess I've got, as I've only had one sip of morning java

Ken, that would probably do it, but would be hard to correct quickly.

Something on the crown

This gun has a brake, so the crown it pretty well protected.

The barrel was getting loose (unthreading)

Excessive leading @ 1200 with the soft cast?

So much for that idea then.

Is the brake integrated? Or was it not on completely?

All good theories, so far. Most of what went through my mind.

OK...gun related keyholing bullets....HAS to be due to bullets not completely stabilizing in the barrel OR getting de-stabilized upon or after exiting the barrel...assuming barrel and bullet dimensions are in spec..."quick fix" makes it even more mysterious!"

So we have analyzed cylinder alignment, barrel alignment, barrel crown...

WHAT are we missing KRAL!!!

X2! I'm stumped if it was not one of the problems already posted.

Lol.....patience, gentlemen. I want to here some more theories before I let the cat out of the bag.

It only took me about one minute to fix the problem; about half that time to diagnose it. But, I did have the gun in possession

Some of the holes in the brake pluged with fowling?

Did the problem go away when you went back to your 325 grain XTP loads? Were your cast loads per chance for another caliber??

Lol...they were Linebaugh's. I didn't go back to the 325s, but the keyhole'n stopped as soon as I corrected the problem.

I'm stumped.

Cylinder indexing?

Loose nut behind the trigger??

Ok....I think all possibilities have been covered; other than the problem.

My grip frame had worked loose will shooting the peppy loads and I didn't notice it. Those rounds may have been unstable also, but I can't confirm that cause I wasn't zeroed for them and they weren't hitting the target. I was just shooting them to make sure my red dot was still holding zero.

When I went to my cast loads, that I was zeroed for, is when I discovered the erratic impacts. My first thought was that my red dot had bit the dust again. But when I walked down to the target, I noticed the keyholes. Since I was shooting from field positions (off my back pack) I was afraid I might have been modifying my pack, but after checking that out there were no holes.

I then started inspecting my gun; that's when I noticed the loose grip frame. I really didn't think that would cause it, but it needed tightened,so I did. All the frame screws had worked loose. After torquing all of them back down, I tried shooting again....WAHLA! Rounds striking 2" high at 50 yards like they were zeroed; two cutting the same hole! Went down to inspect and no keyhole. Shot a few more to verify and still good to go.

Who Wud of Thunkit?

Good to know! Never would have thought of that! I'm the same as Gregg-- thought it would have had to be at the entrance point to the barrel, or last thing as its leaving the barrel.

Good education right there! Think I'll go check my grip frames!

My guess would have been the ammo. Bullets traveling too slow for a twist rate, or something along those lines. At least you identified it and got it fixed.

It makes perfect sense when you think of the gun as a system. The twist was not being fully utilized with the gripframe giving slightly during the slugs travel down the barrel. Probably wouldn't have been as pronounced with a faster stepping round that had less dwell time in the barrel. Kral stumped me when he called and told me for sure. The load is a known load and has always shot well in his gun and others including mine. Pretty much ruled out the ammo right off the bat. It does remind me that I need to go and take a screwdriver to the safe soon

That to me indicates that bullet and that load are on the ragged edge of stability in that gun with that twist. I might add a couple tenths just for margin of error ;-)

Glad you got it figured out, Kim.

So the slugs were not being fully stabilized in the barrel...

I have had POI shift because of a loose grip frame, but no issue with key holing.

Exactly.



Myself as well.

So, loose screw behind the trigger. Just what I thought!! LOL

Exactly 😜