Now that's interesting leading

[jonk]

G33/40 8mm carbine. 21 gr of 5744, 175gr Lee bullet, BAC lube. Only thing different from last time I shot it is, I bought some aluminum gas checks off ebay that don't crimp on like the Hornady ones. I've used aluminum checks before with no issue, but in this gun they were seated below the neck. Which I've never had issue with with Hornady checks, but I think it was an issue here.

Rather than a nice lube star, I got a star of lead at the muzzle, spraying out from each rifling groove. Naturally I had nightmares of having to break out the kroil, long soaks, steel wool, etc.

However: after brushing with a bronze brush and using some Ed's red, the bore cleaned up quite easily. No gray streaks on the patch, looking down the bore I don't see any lead smears. All that leaded was the muzzle itself; the lead flaked off with a light dental pick scraping.

Anyone else ever get leading on the muzzle of a gun but not in the bore?

Given there wasn't any in the bore, the bullet fit is fine I think, it just has to be those checks slipping off (some slipped just in handling the sized bullets), and I'll superglue them from now on; it would also explain the poor accuracy with a load the gun normally does well with.

[338RemUltraMag]

The checks were probably too thin, what diameter is your check shank? Some people on ebay will sell you a shat sandwich and swear it was gold.

Josh

[Larry Gibson]

Non crimp on GCs seated below the neck are probably coming off the base of the bullet in the case before or after the cartridge is fired. Go back to Hornady's or don't seat below case neck. Thicker GCs may help also as could gluing the GC to the base of the bullet. Probably not worth messing with so the Hornady's or Blammer's are the best "cure".

Larry Gibson

[Garyshome]

Glue them on till you don't have any more left.

[runfiverun]

the muzzle leading indicates you exceeded the alloy's limits.
this is something that the gas check helps combat.

[jonk]

the muzzle leading indicates you exceeded the alloy's limits.
this is something that the gas check helps combat.It's WQWW with a few ounces of tin added, with a velocity of under 2000fps (about 1800 iirc). So it has to be that the checks are falling off.

They're good looking checks. Not thin pop can stuff, .014" aluminum as per my micrometer. I think that superglue is the way to go, and/or a different bullet for this gun that has a bit longer nose and doesn't need to be seated below the case neck.

[338RemUltraMag]

It's WQWW with a few ounces of tin added, with a velocity of under 2000fps (about 1800 iirc). So it has to be that the checks are falling off.

They're good looking checks. Not thin pop can stuff, .014" aluminum as per my micrometer. I think that superglue is the way to go, and/or a different bullet for this gun that has a bit longer nose and doesn't need to be seated below the case neck.

The Lee 329-205 is a great boolit that does not need to be seated below the case neck, I shoot it in my M48 with great accuracy.

[leadman]

Just a plug for 338RemUltraMag's checks. They work great with no issues. OP could try these and see if it makes a difference.

[grampa243]

lead or carbin build up??

just say even shooting J-words I have seen a carbin star on the muzzle from powder burning.

[longbow]

I had a Siamese Mauser converted to .45-70 back in the 1970's. Then I bought a Marlin 1895 in .45-70 so was loading for both.

I stuck to top end Marlin loads for both guns just so I didn't have to worry about getting a Mauser rated load accidentally into the Marlin. That and the Marlin loads had enough oomph at both ends anyway.

Same load in the longer barreled Mauser leaded about 2" at the muzzle. No problem with the Marlin. In those days I was not smart enough to slug bores so really have no idea of fits. Not sure if I was running out of lube or getting a bit of gas cutting in the Mauser but it only leaded at the muzzle and only with the top end loads. Since I was not running max. pressure by any means, I decided to add a .410 fiber wad for the Mauser. That solved the leading at the muzzle with no signs of pressure or other problems.

Oh, the boolits were Lyman 457124 (385 gr.) and 457125 (500 gr.) that I shot most of the time and both were plain base.

So, gas cutting, running out of lube or pushing too hard for the alloy I do not know but a bit of protection for the base (which should have increased pressure some) solved it.

That probably doesn't help at all but yes, I have had leading at the muzzle.

Longbow

[jonk]

Update: I glued on the checks with superglue, and the leading disapeared. Accuracy returned to normal. So we found the culprit.

The checks are decent, just not what I was used to. Last time I used slip fit checks, they were fully supported by the neck.