Gas check crimping

[GoBig]

Pretty sure I know the answer, but I want to make sure the best way to crimp these gas checks. Bullet is RCBS 32-170-FN, cast of ACWW +2% tin, lubed with liquid alox. Bullets are coming out right on .324". Gator gas checks. Lee .323 push through sizer. Sized bullets come out .323". Bullet on the right was pushed through nose first and ended up with a skirt of copper/ sharp edge around the circumference, and it doesn't look square to the bullet. On the left was run through base first, appears nearly square with a slightly rounded bottom. I'm assuming the one on the right is not acceptable. Is the one on the left ok?
https://i.imgur.com/gUeupMM.jpg
https://i.imgur.com/jpGzFvQ.jpg

[Yooper003]

I wish I knew the answer, as I too have wondered. When I am installing gaschecks I so times run a few one way & then a few the other.at times I think I have found the best way only to change my mind later. It would make a good test to run 50 or so each way, load with identical components & shoot for accuracy. From your pictures I would not shoot the one with the lopsided base,that’s just my idea.the one on the left looks better but I read where people want a sharp & squared base,you can see a little rounding in that base. Does that make a difference, I don’t know.maybe I will makeup a test with checks crimped both ways & see if I can see any difference. Will have to keep watching here & see if anyone else has any good ideas.

[garandsrus]

You are not sizing the bullets very much so there isn’t enough pressure to seat the gas check while sizing. You will want to seat the gas check first by tapping/pressing the bullet into it, using your press and something over the sizing die opening, or put the gas check on, set the bullet on your bench, and tap the nose with a hammer to seat the gas check. After that, size normally. I prefer nose first.

[farmbif]

good question here, hopefully some of the experts will chime in on it,
great photos, pictures worth 1000 words.
ive yet to have such a problem with Lyman lube sizer unless bullet base was off

[GoBig]

You are not sizing the bullets very much so there isn’t enough pressure to seat the gas check while sizing. You will want to seat the gas check first by tapping/pressing the bullet into it, using your press and something over the sizing die opening, or put the gas check on, set the bullet on your bench, and tap the nose with a hammer to seat the gas check. After that, size normally. I prefer nose first.

Pushing them on by hand isn’t enough? I’ll give it a shot. Will that eliminate the sharp extruded corner on the base?

[BC17A]

I'm not an authority on the subject, but do use the best practices from others on the forum and have outstanding results. A bullet seater plug and a sizing punch is IMO a must when seating gas checks(before crimp). I went one step farther and made custom plugs that contact as much of the boolit nose(ogive) as possible to minimize distortion, especially when seating a GC over powder-coat. I also like to anneal the checks, and found they crimp/size better and tend to keep a flatter base when seated, instead of a crown like the left one in the OP's pic.

Also, the more I look at those pics in the OP, I'm beginning to wonder if those checks are too thick for the shank.

268369 268370

[Winger Ed.]

I seat by hand, then stand it up on the bench to be sure the check is on there square and far enough.

Then I seat/crimp on the lube press base first.
I figure it helps by keeping it square, and there is pressure pushing the check firmly onto the base as it goes in.

Going down into the die nose first- the way the die is tapered a little,
I'd wonder if there was pressure working to push it off,
instead of pressing the check onto the base more when it got in there far enough to crimp.

I'd save the one on the right, along with other ugly children for rapid fire, barrel fouling,
short range practice, that sort of thing.
I wouldn't toss it back in the pot without it spending a little time in the berm first.

[Bird]

If you have good bullet bases, as cast, then the chamber/cartridge pressure will finish seating the bullets that look like the one on the left.
The one on the right, may cause neck clearance problems when chambering the round.

[garandsrus]

Pushing them on by hand isn’t enough? I’ll give it a shot. Will that eliminate the sharp extruded corner on the base?

Most of the time, no. It depends on the mold though, some have a slightly small gas check shank and the gas check slips completely on. Many times the shank is a little too big and it takes some force to push them on. The sizing die will crimp them in place. Sizing nose first, the punch should flatten the base, but it takes some resistance/pressure from the sizing die.

[Yooper003]

I looks to me as if the answer is what ever works the best for you, as well as installing your checks before or after powder coating.

[GoBig]

If you have good bullet bases, as cast, then the chamber/cartridge pressure will finish seating the bullets that look like the one on the left.
The one on the right, may cause neck clearance problems when chambering the round.

This was my thinking as well. Both checks are secure to the bottom of the bullet and the bases look good to me. I need to work on my timing opening the sprue cutter because I'm often left with a tiny bit torn out of the base but I don't think it's a huge issue for this application. I've been wrong before.

Thanks everyone for the responses. I think I'll size base first unless anyone can think of a reason it wouldn't be safe.

The nose first sized checks are getting sized more on one side than the other leading to a longer lip on that side. I tried annealing a gas check and it ended up the same as the unannealed. Sized another base first and then pressed it against a piece of steel across the die opening to flatten and here's how it looks. Less rounded than without pressing.
https://i.imgur.com/zegGkdb.jpg
https://i.imgur.com/Zlqg1kG.jpg
Here we have two typical bases.
https://i.imgur.com/U7TYo4Q.jpg
https://i.imgur.com/V8fNKL6.jpg

[MT Chambers]

Problems like this with gas checks are the fault of the mold makers, when they can`t make a mold with the right dimensions of the gc shank. I seat my gas checks with NOE equip. if the shank is not right. Either way I size them nose first on Star lube-sizer and they come out right.

[GoBig]

Is this indicative of a shank that's too large or too small?

[DHDeal]

Is this indicative of a shank that's too large or too small?

If you are referring to the earlier pic of the cocked GC, probably a fat GC shank. If it were too small then the bullet would sit right down inside the check.

I've got a couple molds that drop a fat shank and it can be a pain. I've bought and use a GC expander for one of those molds and it's just what I had to do. I still use the GC seater that is sold by Lyman on my LAM to seat the checks square before they go into the Lee bullet sizer die. Make no mistake though, those checks are on for life and are seated square. If I ever get a cocked check, that bullet is chunked into a box for remelting. It will not go down my barrel.

[mattw]

Many moulds will allow finger pressure to seat the checks, but for very tight non standard shanks... I seat this way. I think the part is a washer that was not punched all the way thru during manufacture. I wish I had a few more of these.
268456

That LBT bullet is in 41 mag and is a booger to get checks onto. Normally I just seat them by finger and crimp them nose first in the star. I always put them on before I PC.

[fcvan]

Been there, did that, broke it down in smaller steps. I make my own checks, so I can make the checks fit better. I cut my aluminum strips which I anneal. 10 strips makes a 100 checks, so I squeeze with vice grips and immerse in the lead pot for 15-20 seconds. Makes good checks that stay on.

I can adjust the CheckMaker die to make the cup a little more open. I have one shank that is too fat, so I make thinner gas checks for that boolit. I took my push through die and opened it up with a slight taper. I set the check on the shank and start the boolit making sure its centered. As I lift the ram, I bump the base starting the check on square, then push it on through. Annealing, different thickness of material, die adjustment, sizing die opened up a bit.

Oh, I PC everything using a jig that covers the check shank so I'm not trying to seat over a layer of PC. I haven't ASBBPCd these because the jig works sweet. If I get another mold without GC shank or lube grooves I will do that for blasting ammo, put the extra effort in on the target 300 BO or .308 WIN rounds.

[GoBig]

Tried pan lubing and found dealing with sticky bullets to be less than ideal, so I grabbed some powder coat to give that a shot. My application needs work but when I sized a couple with gas checks, they were a tighter fit (as one might expect after adding material) and I ran them in nose first and they crimped on properly. Flat across the base instead of domed like when seated base first in the lee size die and they didn’t extrude the sharp ring around the bottom. I think this tells me that mold is dropping small shanks. Comments or corrections welcomed.

https://i.imgur.com/80AUZt8.jpg

[toallmy]

I'm not a expert by no stretch of the imagination but , you need your check all the way on the cast boolit . In the first picture ( the one sized base first ) the gas check is on the base completely that's the way that seams to work for you even with the slightly oval gas check base that the way I'd move forward .
If you are not getting any distortions on the boolits nose .

[GoBig]

Bit of an update for anyone that stumbles on this in the future. Seems like after a few casting sessions and a few hundred bullets cast, my mold is throwing better bullets. When I rotate the sprue plate you can tell that the gas check shank is tighter to the inner diameter of the mould, as viewed from above with the mould still closed. These have been sizing through the Lee sizer nose first as intended and crimping the gas check on square without the excessive lip as shown in my original post.

[GoBig]

Updating this one more time in case someone has the same problem in the future. My earlier posts claiming victory were premature, with most checks still exhibiting the lip. Sizing base first was bending many of my bullets in the middle. I’ve set aside the powder coat for this rifle because it causes the bore riding portion of the nose to be too fat to chamber without excessive pressure on the lever. Ready to throw my hands up and just buy a new mold and/or a new sizing system I took a long look at the Lee sizing die. The taper leading to the sizing ring was a little rough, but I didn’t think rough enough to cause an issue. Being cheap however I thought I’d smooth it out just in case. Spun up some 320 grit followed by 800 and smoothed it out. Now it crimps the checks on properly. I might have gone too far though because sized bullets are now just short of .324”. I’ll have to see if they chamber in the rifle this weekend. I hope so, I’d like to finally hunt with rifle cone November.

[Bfb]

Try installing a gas check on top of your sizing stem(it will probably be a tight fit) and then run it up thru the sizing die. This will make a “shim” on top of your stem that you place your gc bullets on and then run thru nose first. Basically increasing diameter of sizing stem so gc doesn’t crease down around stem.

[405grain]

GoBig: That's a nice write up regarding the problems you've been having with the gas checks. With hunting season coming up your best bet is probably to go with conventional bullet lube. The powder coat is going to increase the diameter of both the gas check shank and the bore riding section of the nose. These are going to be separate problems to solve. If you're using a Lee push through sizer, here's something you can try; Take a piece of 1/8" thick flat steel - only needs to be an inch wide by 3" or 4" long. Place your bullet with the gas check on the shank on top of the "push through post", and hold that piece of metal against the bottom of the die. Pull the handle on your press to raise the ram, and when the nose of the bullet contacts against the piece of metal it should seat the gas check on the shank. It should only take a little bit of pressure, not Godzilla strength force, to square up and seat the gas check. Then let the ram down a little bit, pull the piece of metal out of the way, and then push the bullet up through the sizing die. If this works OK it should seat the gas check on square and then crimp it in place. After the bullet is sized try swirl lubing them with either Lee Liquid Alox, or with 45-45-10. Once this lube coating has dried on see how they shoot.

I was having a problem with powder coating bore riding bullets. I like bore riders because they are very accurate, but the powder coating was making the nose too fat to chamber. I worked up a process where I was able to powder coat the driving bands, but leave the nose bare. Even though these are gas checked & powder coated bullets, I swirl lube them anyway. I did a write up on them last year and called these things "hybrid bullets". It's really labor intensive to make them, but they work good. Because you're up against the clock with hunting season approaching I think you should go with the more traditional approach and just size and lube your bullets. Get the venison first, then experiment around to see if a different mold or technique might work better.

[GoBig]

I have tried seating checks as you suggest while trying remedy the problem and it didn’t help. The checks seat well with minimal finger pressure. Powder cost has been abandoned for this bullet because of the issues you point out. One day I’ll get a mold appropriately for powder coat with a plain base for plinking. After polishing the inside of the size die, the checks crimp square and properly, with no lip. I’ve pan lubed with a batch of Ben’s Red and will load some test rounds this weekend with 3031, to be fired as schedule allows. Maybe one day I’ll get a lube sizer, pan lubing is messy and time consuming. I will look for your write up. I thought about trying to powder coat only the drive bands but couldn’t think of an efficient and consistent way of doing it.

[oley55]

I have found the NOE Mold tools to be the answer to most all GC seating problems. The gas check expanders for my over sized .434" bullets and the too much PC on the boolit base, the floating gas check seater that nearly always seat the checks squarely, and the boolit chamfer tool. I find seating base first through any of the Lee type (and NOE) sizers works best and NOE has an adapter to hold NOE nose punches (Lyman/RCBS and Saeco types).

https://noebulletmolds.com/site/product-category/gas-checks-tools/
https://noebulletmolds.com/site/shop/gun-parts/tools/bullet-base-chamfer-tool-power-tool/

[Bfb]

Ok, if gc has “rim” on bottom just run your gc thru your sizing die… then put your gc bullet on that “shim” you just produced and they size with no “rim”. Sorry but I thought this initial thread was about gc base deformation and that will solve that problem powder coated or not.