Barrel starting to lead...

[blueline541]

I'm shooting a 175 gr. cast bullet (Lyman mould, straight WWs) through an HK USP .40 with a polygon barrel. I started with 5.0 gr. of WSF which produced fantastic accuracy. I fired two hundred rounds which caused enough barrel leading just past the chamber to require a good five minutes of scrubbing to clean.


I reduced the charge to 4.5 gr. of WSF and the accuracy was atrocious. One hundred rounds produced much less leading, also past the chamber, which was cleaned out after three passes of a bronze brush.


I plan on testing various charges of WSF between 4.5 gr. and 5.0 gr. in an effort to keep the accuracy and lessen the leading. Beyond that what are my options? I already swapped the FCD with a taper die before I began loading cast bullets. And I slugged the barrel, .398 I believe, and am sizing at .401. Could this be something I have to learn to live with because I'm shooting a polygon barrel?

[cohutt]

dem polly gone barrels get lead sticky dey say

[Boge]

FWIW, there is an older guy I know who shoots at a local range and he blew up an H&K shooting lead. The gunsmith there told him several times he was playing with fire but needless to say, he did not listen and "KABOOM"!!

[MakeMineaP99]

Leading in your throat is a sign of two things:

Undersized bullet.

Too hard of a bullet.

I don't think you have an undersize bullet, since you're sizing at 401 thou and I assume culling out anying undersize slugs when you lube.

You may want to soften you alloy some. Or you can bump up your charge some to get the bullet to seal, as you're not sealing when the gas cloud hits the bullet. Or a combination of both. When lead, you really have to wring out your loads to the nth degree.

You can run lead in a poly barrel, despite what you may read on the internet. You just have to apply best practices for lube, size and develop your loads.

[blueline541]

I have load data from a rather new manual that lists the starting load for a 170 gr. lead bullet at 5.2 gr. WSF and max around 6 grains. I'll start at the minimum and go from there and see what happens.

[BigSlick]

Fotay can be a biyotch wit a 175 Lyman. Nice bullet all da way, but all barrels weren't designed ta shoot dat bullet (ideally).

I would do a couple things first before I went to dealin with changin alloy right off.

First, find out what BHN ya workin wit. Like AdamN says, 50/50 a be a good place ta start.

Second, dump some ALOX on some of da bullets ya already have an see what dat gets ya.

If ya lead is already soft enough, an da ALOX cleans things up a little, I would take a hard look at da barrel condition. You might have some copper fouling in da throat leftover from jacketed causing issues.

Gotta scrub it squeaky clean if ya want best results, copper fouling and lead ;)

You bullet dimensions sound good ta me, but maybe a cerrosafe cast of da throat a shed some light on da situation. I've seen em all over da place. Just because ya groove dimension is good, doesn't mean da throat isn't fat.

If it is, you gotta decide how far ya wanna go with sizing. If groove size is .401, I would prolly be OK wit going up to maybe .403, dependin on if a round would chamber at any OAL I was willin to work with.

Cast da throat, get a good dimension an see if da ALOX helps any, after ya make sure da barrel is completely free of *any* fouling.

You a find happiness, jus gotta work out some details...

[blueline541]

I went to town on the barrel with Sweet's 7.62 before transitioning to lead rounds, but I'll hit it again and see if it makes a difference.



This has to be one of the most fun aspects of shooting I've encountered so far. And the volume of bullets is staggering.

[MakeMineaP99]

Blueline, if you want some cerrosafe, I can send you some.

[blueline541]

I'll keep the offer in mind. I'm going to poke at it from several angles and see what happens. Worst case scenario, I have a very accurate round which requires a little scrubbing now and then.

[BigSlick]

I went to town on the barrel with Sweet's 7.62 before transitioning to lead rounds, but I'll hit it again and see if it makes a difference.

This has to be one of the most fun aspects of shooting I've encountered so far. And the volume of bullets is staggering.

You might wanna pick up some Hoppe's Elite foam an foam dat barrel real good (as in full) an let it sit for a while.

You a be amazed at what comes out of it even after it looks clean. Amazing stuff for what it is. Also sold as MPro7, same stuff, different label.

If ya barrel doesn't have a fat throat, check closely for rough spots, they're rare, but it does happen. Dull reamer, crappy final polish etc..

If ya can get a cerrosafe cast, keep in mind the final dimensions are .002 (maybe .003) off, don't remember exactly offhand. But the cast dimension (factored) will tell you for certain what you're workin with.

EFK Fire Dragon has a replacement barrel for a USP for about a buck an a half. Not sure about LW or SL

[AdamN]

With the polygon barrel Im not sure. The only polygon barrels Ive seen that were lead friendly were the Glock 45acp.

Shooting/cleaning a few times may help, if not just buy a cut rifled barrel. Then you can swap barrels if you shoot lead or jacketed

[blueline541]

EFK Fire Dragon has a replacement barrel for a USP for about a buck an a half. Not sure about LW or SL




Although I'd prefer to make this polygon barrel work, I'm not ruling out a replacement barrel down the road. I don't know the first thing about EFK Fire Dragon's barrels other than their price ain't too bad. Anybody here have any experience with this company's product?

[Slim Chance]

I've had much better luck with very hard cast bullets in my Glocks. Seems like softer alloys "skid" just ahead of the chamber before grabbing the rifling.