Lead smear on checks from shaving lead off shank?

[mongoose33]

Just bought a new RCBS 38-158-SWC mold from a buddy who bought it at an estate sale.

I've never used gas checks, so this mold is a perfect opportunity to learn. Bought some .357 checks (Hornady), and yesterday I casted up some boolits to see how it all works. I used both linotype and #2 as alloys, the boolits drop about .360 with lino, just over .358 with #2.

Well. The checks won't fit over the shank at the base of the boolit. Sometimes when I seat them with my Star lubesizer, they'll fit very nicely; sometimes one side will shave some lead from the boolit, and then the lubesizer will iron that lead onto the check. I can scrape off that lead on the check with my fingernail, but it seems like something's not right.

Here's a pic; the one on the left shows the lead on the check, the one on the right, no such lead:

152297

Is this just something I have to accept? The checks are seated squarely; they just shave lead about half the time.

[Retumbo]

Don't worry about pretty, how do they shoot?

Plain base?

[mongoose33]

Don't worry about pretty, how do they shoot?

I'm not worried about pretty; the gas check will be inside the case so no one would see it anyway. I expect to PowderCoat these as part of the process, and if I'm struggling to get the check on now w/o shaving the lead, well, won't happen at all if PC is on there. I'd rather attach the gas check prior to PC'ing.

I haven't shot them yet. Lead smears on the check, wondered if that's typical, and if so, what do people do about it, if anything? I'm looking to push these hard through a Rossi model 92 lever action, which is why the gas check. I'll also try them as plain base after PC'ing, perhaps might coat them upside down so the nose isn't coated by the base is.


Plain base?

It is a gas-checked design.

[Nueces]

Some folks deal with it by turning up a tapered punch to slightly flare the gas checks.

[Retumbo]

It is a gas-checked design.

How does the gas check designed internal dimension stack up against the base dimensions? There is a formula for gas check dimensions/material thickness/base dimension...


I think this was stickied somewhere but can seem to find it. Installing gas checks requires the checks to be accurately sized to fit your cast bullet.

The optimal thickness of the base material of the check can be determined using this formula:

T = (Sd - SHd) / 2
T = Material thickness required.
Sd = The Bullet Final sized diameter
SHd = The Bullet Gas Check Shank Diameter

Using this formula will create checks designed to fit tight to the gas check shank of your bullet. I would not trust neck tension alone to hold your checks on. This can create problems with the checks simply falling off in the case or coming off as the bullet leaves the case and heads down the barrel.

Same thing goes for overly tight checks

[Calamity Jake]

Some folks deal with it by turning up a tapered punch to slightly flare the gas checks.

^^^^^^^^This^^^^^^, or you could send the mold back to RCBS stating that the GC shank is to big,
the mold they replace it with may be smaller or it may not.

[mongoose33]

Still working on this--thanks for the input.

Retumbo, of course, hit to the heart of the matter, i.e., how do they shoot? Don't know yet, though what I'm ultimately looking for is something I can push in my Rossi. So I hand-lubed about 30 of them after installing the checks and ran them through my Lee push-through sizer. I'll make up some test rounds to work up some loads and see what I get. Sadly, I won't have that finished in time to go out today to shoot them--and that's a shame, gorgeous 60+ degree day today.

152324

[MT Chambers]

Check out NOE's equip. used to seat GCs square, even for molds that are machined wrong for the check.

[mongoose33]

Check out NOE's equip. used to seat GCs square, even for molds that are machined wrong for the check.

Thanks--that's the kind of thing I didn't find when I did searches here.

Do I just need the gas check seating die, or do you think I'll need the bullet base chamfer tool--or both?

Goose

[bangerjim]

I tap mine on with a small hammer when they do not snap on. They either run them nose first or base first thru the Lee sizing die, depending on the shape of the nose. Round noses go catty-whompus and ruin the check base first.

All my Hornady Cu checks go on perfectly that way.

banger

[mongoose33]

I tap mine on with a small hammer when they do not snap on. They either run them nose first or base first thru the Lee sizing die, depending on the shape of the nose. Round noses go catty-whompus and ruin the check base first.

All my Hornady Cu checks go on perfectly that way.

banger

What would you do if they didn't go on perfectly, if they shaved lead as they were forced on the shank of the boolit? Would you ignore the lead smear on the check, as per the picture in the first post? Just scrape that off and proceed? Switch to knitting as a hobby?

[bangerjim]

I PC everything, so a lead smear would be no big deal to me. PC after putting on GC solves any problems you may think you would have with leading. But I have never seen a lead smear on any of my GC'd boolits, 223, 30, 44, and 45 cal. Mabe the lead would come off in travel? I have no idea. But PC protects the barrel. So you would have exposed copper!

If mine do not snap on firmly, I set them nose down on a soft wood block and gently tap the check on with a small hammer. That forces it on and totally flat. Sizing then crimps it on tight and straight. Usually 1 in 15 needs that. I use only quality Hornady Cu checks, and not those home-brew things some try to use to save a couple cents. And NEVER Al checks. Tried them...hated them.

[mongoose33]

I PC everything, so a lead smear would be no big deal to me. PC after putting on GC solves any problems you may think you would have with leading. But I have never seen a lead smear on any of my GC'd boolits, 223, 30, 44, and 45 cal. Mabe the lead would come off in travel? I have no idea. But PC protects the barrel. So you would have exposed copper!

If mine do not snap on firmly, I set them nose down on a soft wood block and gently tap the check on with a small hammer. That forces it on and totally flat. Sizing then crimps it on tight and straight. Usually 1 in 15 needs that. I use only quality Hornady Cu checks, and not those home-brew things some try to use to save a couple cents. And NEVER Al checks. Tried them...hated them.

Thanks--my intent eventually is to PC them--right now it's a pain to set up the whole process to ESPC them and then bake them and then tear it all down. So i thought I'd run them through as lubed boolits to at least begin working them loads up. Part of the concern was that if I can easily scrape off the lead on the check w/ my fingernail, there may not be a particularly good substrate and may flake off in the barrel.

To get the check on prior to PC'ing I need to run them through a sizer. Normally when I size PC'd boolits, i spray them w/ a weak solution of Alcohol/Lanolin to lubricate them going through the sizer. I don't know what that would do to the ability of PC to adhere--though maybe the only answer to that is to wash them, post-sizing but pre-PCing, in acetone.

If you size boolits prior to PC'ing, do you lubricate them with something? if you do, do you wash/rinse them in something, or do something else? Does it affect the ability of PC to adhere?

[gpidaho]

A very simple gas check flaring tool design was posted by Ben. Use the shank of an appropriate sized bolt, chuck it up in a drill press and bevel one end, to adjust the bevel to the size that works best just bring the tapered end down (still chucked in the drill press) against a file or old honing stone. Gp

[bangerjim]

Thanks--my intent eventually is to PC them--right now it's a pain to set up the whole process to ESPC them and then bake them and then tear it all down. So i thought I'd run them through as lubed boolits to at least begin working them loads up. Part of the concern was that if I can easily scrape off the lead on the check w/ my fingernail, there may not be a particularly good substrate and may flake off in the barrel.

To get the check on prior to PC'ing I need to run them through a sizer. Normally when I size PC'd boolits, i spray them w/ a weak solution of Alcohol/Lanolin to lubricate them going through the sizer. I don't know what that would do to the ability of PC to adhere--though maybe the only answer to that is to wash them, post-sizing but pre-PCing, in acetone.

If you size boolits prior to PC'ing, do you lubricate them with something? if you do, do you wash/rinse them in something, or do something else? Does it affect the ability of PC to adhere?

No lube of any kind needed. Unless your "swaging" (!!) rather than just "sizing", there will be no leading in your die at ~ONE (1) FPS! I do it all the time. Never a problem when using the CORRECT die size for the CORRECT boolit diameter.

And you do NOT ever need lube for shoving PC'd slugs thru a die either. The PC is slick and goes thru like magic.

Keep all forms of greases and lubes away from boolits you are going to PC. Make sure your dies are grease-free B4 starting. I do not allow greasy lubes in my shop! Or silicon sprays. Only Unique Case Lube for rifle cases. And that is lanolin.

All that coating and washing your are discussing takes waaaaaaay too much valuable time.

banger

[Seeker]

My apologies to the OP for asking a question on his thread.
Just before I found this thread and read it, I PM'd Sagebrush with a Q on smearing. Only it's quite the opposite. My plain base aluminum gas check seams to be smearing up the boolit as it is being pushed through the die. Base first of course. Any thoughts on this?

[popper]

Mongoose - sounds like the shank is too big. A poster here suggested using hi-temp paint, applied to the shank part of the mould only to make it cast smaller. If you aren't getting finning from not closing the mould tight enough, could be the problem, or an out of round shank. Definitely clean off the lead on the GC so it doesn't cause barrel leading.
Seeker - I'm assuming pistol boolits, as long as smearing isn't lopsided it shouldn't be a problem. Your alloy must be pretty hard to be able to size base first.

[bangerjim]

I cast ~10 to 12 hardness and crimp on GC's base 1st all the time. Nothing super hard here. No GC or lead smearing at all. FP boolits only, as RN's will not go thru straight!

[Mohavedog]

Mongoose - Hornady gas checks have a slight burr (lack of better term) manufactured into the inside of their gas checks. On a properly sized boolit shank this burr does a great job of crimping into the shank and won't come off and I love 'em for this feature. However, this burr can cause the exact problem you are having if the shank of your boolit is too large. In your case the easiest fix would be to expand those Hornady's a bit before installation.
Contrary to others' opinion I find properly fitting aluminum gc's work very well indeed. Aluminum checks may solve your fitment issue since they won't have that little burr inside the cup. Now, after saying that, aluminum checks can and do cause problems of their own that makes many not to like 'em. They have to fit right, period. Too big for your shank and they won't stay on, too small and you'll have the same kinda problem the Hornady's are giving you.
I make my own checkmakers and have discovered via trial and error most reasons checks don't work right. The biggest reason there are problems is that one size maybe doesn't fit all. I have molds that one size check fits great and other molds that same check doesn't work at all.
Hope I added something helpful. Mohavedog

[CHeatermk3]

You could lightly chamfer the bases of your boolits-the outside part of a neck-deburring tool could work well esp. if motorized.

Can you get a measurement of the shank? Do the Lino castings differ from the L2 alloy castings on the shank as they do on the body bands?