Keyholing Reloads

Member 34319 · Apr 20, 2019

Based off the information given I'm going to guess that the velocity of your reloads is too slow to stabilize.

Sounds like a weaker ejection pattern.

All of this is super interesting though. Especially given that the distance this is occurring at is only 50 yards.

Consider me tagged for the cure.

daved20319 · Apr 20, 2019

I have an older 181 series Mini, haven't checked it but it should be a 1 in 10" twist. Oddly enough, it doesn't like 55 gr. bullets, 62's shoot much tighter, haven't tried anything else yet. I was getting around 2" or so at 50 yards with a red dot. Changed the recoil spring to an extra power one, and groups instantly shrank to 1" at 50, no clue why, but I'm not about to look a gift horse in the mouth. I've also changed the gas bushing to a .050", and have an UltiMAK rail on it. I haven't had my Mini very long, only have a couple of range trips with it, but based on the little I've learned so far, I'd say try a heavier bullet, and maybe replace the recoil spring. If that still doesn't help, it's time to get it to a gunsmith to verify a shot out barrel. Good luck!

Dave

DizzyJ · Apr 20, 2019

Tagging.

41mag · Apr 20, 2019

Keyholing ocurred in one of my projects a decade ago. A trusty mid-70s Marlin 45-70 that had never been more than moderately accurate, was on long-term loan from an ill friend. I determined to ignore the 'micro-groove' business & assess what modest REAL loads of the Holy Black in assorted lead boolits, 300-325-350-405-500 weight.

Loaded 10 of each with proper charges & set out to the 50yd line.
Keyholing many loads & missing the entire target with others. Frustration.

Cleaned & recleaned the rifle bore. No effect. Continued keyholing. Various fiddling with various Black Powder. No improvement with another round of specially loaded shells.l Dug out a box of the factory 'Leverevolution' smokeless/jacketed thingies, and voila!!! Return to normal modest accuracy.

I had read up on various theories of the cause. Conclusion was Marlin factory knew what it was doing advising 'lead projectiles are not suitable' for that kind of rifling.

This doesn't solve OPs issue but does reinforce the notion there IS a cause however hidden it may be, for such erratic performance. Good Luck.

ConcernedCitizen · Apr 20, 2019

Dyjital said:
Stability also has a lot to do with speed of the rounds.

What are your reloads running for velocity? Have you chron'd them?

What's your barrels twist rate? Not MFG, but brush down bore method.

When was the last deep cleaning?

@Baseacegoku and I were working through an issue with his AR. My reloads ran fine, everything else keyholed. No solution yet with his.

Thank you! I meant to post this last night, but spaced it after all of my other long-winded posts.

There could be considerable copper fouling, so it might be worth using some copper solvent to see if it helps.

edzz · Apr 20, 2019

So... you have some comercial loaded ammo that is not keyholing. As an experiment pull the bullets from a few rounds of the ammo that is not keyholing and replace them with the bullets you are having problems with loaded over the factory powder charges. Load the bullets pulled from the factory ammo in cases you have prepped and charged with the same powder load your having problems with. Doing so you may identify if it's your load or the bullet causing the problem.
As cheap as chronographs are these days...

Stomper · Apr 20, 2019

The first thing to do (which is obvious), is to stop reloading using those mini clothes iron game pieces from Monopoly games....

CLT65 · Apr 20, 2019

I had a keyholing issue many years ago, in a Marlin 1894 .44mag rifle. I suspect that it was a very different issue to what you're having, but I'll throw it out there anyhow for consideration.

It was the late '80s and I was just getting into guns and reloading. My dad had the Marlin that he never shot, and picked up a couple boxes of gun show ammo, loaded by Miwall, 240gr JHP. They wouldn't even hit the target at 100 yards. On one shot I saw a branch fall out of the tree 10 feet above the berm. Moved in closer and they were all over the place.

I got the idea to pull a few apart, and inside was about 11gr of powder, surely fast pistol powder. I dumped it out and replaced it with the appropriate charge of 2400 as I recall. Voila! I could hit the target! Something about that combination of bullet, powder charge, and rifling twist just didn't work.

I know it's off topic, but interesting that Marlin microgroove rifling and lead bullets is mentioned. I fiddled with that old Marlin .44mag for years before I finally found the right cast bullet that would shoot well in it. It's not easy, but it can be done. That's a subject for another thread...