Keyholing/tumbling boolits - what am I doing wrong?

[Wardo1974]

I'm loading some 405 grain boolits today in my .45-70 for the first time.

The boolits are tumbling and I have no idea why:

Barrel, slugged at .457 (Browning 1886)
Boolits, sized at .459, lubed, soft lead
Load: 32 grains of IMR 4198 behind the 405 grain boolit, for about 1450 fps according to the tables.

I am using a Lyman die set, with the "M" to flare the cases to enable the boolits to slide in better.

The bullets are tumbling by 25 yards out. No leading of any kind visible in the barrel - shiny clean.

I wondered if I'm crimping it poorly? I pulled a boolit and it looks tapered near the end just beneath where I crimped. It does measure less than .459 in that spot. But the main driving band out front remains fine of course, since it's outside the case.

Am I crimping too hard? Or is this even the problem?

Would a FCD be less "squishy" on my boolits?

[wv109323]

Sounds like you are doing everything right. My first guess is the base of the bullet is being sized down when seated since it is soft lead.

[labradigger1]

New or used gun?
Any loose spots when running a tight patched jag through the bore?
Last time I had a gun keyhole I had a loose spot from 1" to 3" rom the muzzle. Cut off, re crowned and problem solved.

[Reg]

Check the crown, look carefully. Try .458 dia. Twist ? Out of round in bullet ? Check bore with tight fitting patch. Try different weight bullet. How is the leade or the transition from chamber to bore. Have seen some factory chambering waaaay off, TIR wise. Check this with a chamber cast.

If you are tumbling at 25 yards it has to be something obvious.

[Wayne Smith]

What is your gun? Trapdoor's are notorously .360+, you may be way too small as well. Need data.

[mjwcaster]

What are you measuring with?

I thought I had good boolits with my first mold, until I got a micrometer and found that the boolits were way out of round.
Leaded like crazy.
Better round boolits are working fine.
Just could not measure small differences with calipers.

[44man]

Some Brownings have 8 lands and grooves and are sort of like a micro groove so it might need a .460" boolit.
I don't know about the 1886 but the high walls are 8 groove.
Look at fired cases and see if any crimp is left on the brass, you might have the boolits getting sized by the crimp. Try harder boolits. Even though you find no leading you could be skidding the boolit.

[Wardo1974]

After some fiddling, I think the boolits went undersized from seating and crimping.

T

[Wardo1974]

As a follow up for guys who offered advice: I seated and pulled a bunch of boolits to measure them. Even without crimping, the case tension was putting the boolits from .459 down to .457 or so. Pure lead boolits, so this shouldn't be a surprise I guess. Even seated without a crimp at all and fired single shot from my repeating rifle, they tumbled.

I wound up powdercoating the boolits using the standard tumble method, and the added layer of PC took the boolits up to .462 or so in size. I decided to not resize them down and use them as is.

Reloaded thusly, suddenly the shots straightened out, and I could make 1"- 1.5" groups at 50 yards in the rain off a picnic table through my Marbles peep sight.

So at the end of the day, my original boolits were too small. Thanks everyone.

[44man]

Good show!

[mjwcaster]

Sounds like a winner.
I just had Lathesmith make up a larger expander for my dillon 550 to help keep cases from swaging down my 9mm/380 boolits.
Now I just need to try it out, and get my mold to drop round boolits.
Maybe this weekend.

[williamwaco]

Welcome to the club. You are now a certified problem solving reloader.

I am sorry to inform you - There is no known cure.