Gas Checks vs Shank Size

[45nut]

Can someone put up a table of the various sizes available and the "correct" ones for the available molds please. Seems shank size from the different mold makers past and present differs greatly. I would like to make this a sticky.

[felix]

GATORS MaxShank Description
.224 .214 .22/.224
.243 .233 .243/6mm
.257 .243 .25/.257
.264 .252 .264/6.5mm
.277 .253 .270/.277
.284 .250 .284/7mm
.308 .284 .30/.308
.323 .301 .323/8mm
.338 .327 .338
.348 .320 .348
.358 .341 .35/.357/.358/.360
.375 .354 .375
.410P1 .397 .41 Lyman (very thin)
.410P2 .378 .41 BSS, NEI, MM (very thick)
.416 .393 .416 rifle normally
.430 .402 .44/.430
.452 .426 .45P/.452 pistol (thin)
.458 .426 .45R/.458 rifle (thick)
.475P .445 .475 pistol (thin)
.475R .445 .475 rifle (thick)
.500 .458 .50P/.500 S&W pistol
.512RL .466 .50R/.512 rifle (long)
.512RS .466 .50R/.512 rifle (short)

[45nut]

Thank you felix, exactly what I was after.

[45 2.1]

Can someone put up the physical dimensions and weights for the gas check itself for all calibers available?

[robertbank]

Would 8MM gas checks work for the .303 British? Graf has gas checks in 8MM bot no .30cal which is what I have been using.

Take Care

Bob

[felix]

Yes, Bob, but under duress only. The dies might not hold the check square on the bottom of the shank before compression. You risk sizing one side of the check longer than the opposing side, i.e., lop-sided. ... felix

[robertbank]

Thanks Felix, I'll wait for Graf to get some in. I have enough to do me for awhile.

Take Care

Bob

[Tom Myers]

This is a grid showing the gas check dimensions that I use in the bullet drawing software. When I get some more samples of the Gator checks and some time, I will add them to the database and incorporated a choice of brand name that the shank is to fit.

The software simply starts the shank at 0.002" under the "B" dimension and tapers the shank up to 0.002" over the "B" dimension. The correct height of the check is then drawn on the finished bullet image.

Ideally, 0.001" under "B" dimension generally produces the desired "snap fit" but, in my opinion, it is too easy to go too far and have an oversize shank. Better to be slightly undersize and have the ability to lightly lap the mold shank to fit than to have to expand each check to fit the shank before sizing.

http://www.tmtpages.com/LinkSkyImages/forum_images/Gas_Check_Dimensions.gif

[44man]

Good info guys. Now to figure out what size to cut the cavity in the mold---Hmmmm, more hair just fell out.

[felix]

Tom, the 512 Gator checks are of two flavors: rifle long, and rifle short. The lengths are 120 for the long, and 080 for the short. The 500 S&W pistol is of the short variety at 080. Looks like the Gator and Lyman for the 25 caliber are the same, except Larry tries to have a more rounded bottom on his checks. It appears his checks (in use) are considerably softer, and the more rounded bottom provides for some spring-back from the punch. His maximum shank might be a 1000s smaller as shown in the table, but I would not count on that in reality because of the rounded bottom. So, like you say, it is best to be on the safe side and make the shank a 1000s too small. We will get these checks on the GB list as quickly as possible. Any samples that I can get for you would not be kosher because Larry told me he is going to use a new lot of metal for these and all the smaller calibers that use this thickness of metal for our coming up GBs. ... felix

[45 2.1]

Need Hornady 416 and somebodys 475 checks to be added also along with the changes from Felix.

[hivoltfl]

Could someone give me a shot of info on annealing gas checks? never been down that road but would like to try it on a 152gr Loverin bullet that has a large shank and I understand this might help cut down on culls? Thanks in advance fellas.

Rick

Sorry guys I didnt read down far enough, I get the idea.

Rick

[charger 1]

Yes, Bob, but under duress only. The dies might not hold the check square on the bottom of the shank before compression. You risk sizing one side of the check longer than the opposing side, i.e., lop-sided. ... felix

Right you are Felix. I recently got a 460 mold that the maker made a booboo on and made the shank .010" big .425-.426 it was so I made a little tool to bell the check out. Worked fine. Ran em through the lee sizer. Then when I lubed em in my RCBS lubesizer (I do it in a two step. I'm a believer that sizing and flight direction should be the same) some of them were great, some left big gobs of grease underneath. I get fliers. When you carefully look at em under glass one side of check always has more sizing contact. I'm sure the .010 oversize is ruining accuracy

[felix]

Yeah, if the mold is a prized one, you might consider someone like Buckshot make you a luber machine die to shrink those boolit shanks to fit the "standard" checks. The die would be nothing but a solid roll stock (aluminum) with the top center shaped dimensionally correct as to swage according to the check length and diameter. No die machining would be required to hold the die in place because the residual lube from the last operation would be sticky enough to hold the die in place. ... felix

[charger 1]

Yeah, if the mold is a prized one, you might consider someone like Buckshot make you a luber machine die to shrink those boolit shanks to fit the "standard" checks. The die would be nothing but a solid roll stock (aluminum) with the top center shaped dimensionally correct as to swage according to the check length and diameter. No die machining would be required to hold the die in place because the residual lube from the last operation would be sticky enough to hold the die in place. ... felix

Well it is OK bro. My mold man's middle name is honor. He's got another commin. Thanks anyhoo

[Newtire]

Had a whole box of 8mm Sierra crimp-on gaschecks that won't fit the Lee 175 gr. so here's what I did. I put a .44 case trimmer pilot into my little drill press & expanded them out to fit the shank. Will break down & buy a box of checks soon as I use these up. Never saw these before or since. I either got these off E-bay or had them under the bench from the old days.

[Marlin Junky]

Has anyone ever tried to put a well annealed .375 cal. gas check on a .35 caliber boolit? The reason I'm curious is because I thought of trying this with .360" SAECO 352's shot hard from a wide grooved 336. The .35 Hornady checks have a tendency to separate form the boolits. I currently don't shoot .375 cal. rifles and if it won't work for sure, I don't need to order more shootin' supplies that will end up collecting dust (besides, I already spent over 1000 bucks today on gun stuff). I was thinking the annealed .375 check could be formed by a top punch in the Lyman 450 that fills the .360" die (punch number 141 comes to mind as a possibility) and then applied to the SAECO 352's. Make sense?

MJ

[Ben]

I ordered a new SAECO 352 about 2 yrs. ago , my .35 cal. Hornady gas checks didn't fit well at all. Very loose. You could pull them off with your finger nails.

I figured that at the prices SAECO's charging for their new molds that they could provide a better product than what I had received.

I called them on the phone. The fellow wanted to give me the " run around " at first. He told me to change my alloy, etc. He got a little argumentative. I told the fellow that I didn't plan on spending any time arguing with him.

I told him that I planned to use reg. WW's and that I also planned to send him the mold and 10 of my gas checks and that I wanted a tight fit....PERIOD ! ! I told him I didn't plan on using HIS alloy , that I planned on using my alloy !

About 20 days later I received a new mold. This one is PERFECT. No loose fitting g/c's now... I believe the 1st mold was " way out of spec." on the gas check shank of the bullet.

Ben

[Hank10]

Newtire, I've got 2 or 3 boxes of those 8mm Sierra GCs. Don't recall where i got them , had them for a loong time.
Ben i've had the same experience with Saeco but didn't turn out as well as yours.
I have 2 Saeco molds, 1one .38, one 45 that won't take the GCs. I called them, sent the molds in. The guy in customer service said he didn't know anything abouts cast bullets but his mold guy told him their GCs would fit. I asked him to send me a few of his GCs and he did, they were exactly like mine, every dimention miked the same and they would not go on the bullets. The GCs were Hornady, the shank on the bullet was too big. I have another Saeco 4 cav. that the cherry was put in too deep and it had a 1/8" extention on the base that was part of the shaft was about .375 the bullet was .452. I put it in a mill and milled 1/8" off
now it's fine and although I have some good Saeco/Cramer molds I won't buy any Saeco/Redding molds.
H10

[Axmire]

Being new to the world of gas checks, as I understand it, a 9mm would use a gas check of .35, right?

Thanks in advance.

[RayinNH]

Yessir, welcome to the site too...Ray

[thehouseproduct]

What about some of the guns that have a 305/316 dimension barrel? Do they still need to be limited to a 0.283~0.284 shank?

[Molly]

http://www.thegascheckstore.com/home.html

This is a neat little site where you can buy gas checks of varying thickness and diameters to match your bullet's gas check shank. Prices are reasonable too!

[Rodfac]

I have two Lyman molds for the old Thompson designed, #429215 GC bullet. When cast from WW alloy with just enough tin added to ensure good fill out, I find it impossible to seat Hornady crimp on Gas Checks. In frustration, as I had nearly 3000 of them, I experimented with various methods of slightly flaring the Check to allow it to fully seat on the bullet shank prior to crimping in my old Lyman 450 sizer/lubricator.

I ended up using a fairly large ball peen hammer for a flaring tool. I polished the ball end to a mirror finish (well at least down to 800 grit), then pressed it against the new check, set cup up on my bench vice's anvil. With a vary light tap from a 2nd hammer, it flares out just right. Initially I tried it on about 50 of them, thinking that accuracy would suffer from the flaring operation, but not so. My 1964 vintage Marlin 336 in .44 Magnum shoots them into nice tight 1+" clusters at 50 yds with a Lyman Peep Receiver sight and 66 yo eyes doing the steering. This rifle needs .432" bullets of lead alloy, minimum, to shoot accurately and avoid leading issues, which luckily is the "as cast" dia. of those two 429215 molds. I use a Lee push through sizer in one of my single stage presses for sizing in this off-beat dia. as Lyman didn't at the time offer that size for the 450 too.

In a pair of Ruger .44 Magnums, 3 Ruger .44 Special Flat Tops, and a Smith 429, sizing the whole shebang to .430" does marginally better, but not by much; roughly a 1/4" at 25 yds in group size. All of the listed guns will do an honest 1" for 5 at 25 yds if I'm having a good eyes day.

Recently, I visited my son who's got a 1903 vintage Winchester M-92 in .44-40. I'd cast him up a bunch of those 429215's for use in his lever gun, but had not sized them, nor seated the checks. Talking it over, and demonstrating the ball peen hammer method to him, he suggested using a large carriage machine bolt for a flaring tool. (The one with the rounded dome end.) We've not tried it as yet but the dome of the bolt is ok, radius wise, to prevent it from bottoming out as the edges of the check are flared, so we'll see. The bolt would offer a bit more convenience than wielding that big ball peen hammer around.

In operation, I place 6 or 8 of the checks, cup up, on the anvil then flare using the two hammers as previously described. Works well for me, and the accuracy can't be beat with my guns. The method sounds time consuming, but really doesn't amount to much. Yesterday AM, I spent an hour and a half at it, including finding the hammers after a year's lay off etc. By actual timing, I averaged 6 checks flared per minute; that's roughly 360 per hour. Plenty for my purposes.

Those under size Hornady checks (or an oversized pair of Lyman molds) are about gone now. Don't know if Lyman checks would work better, or if newer Hornady's would slip on better.

HTH's Rod

[Newtire]

I got a mould from Lyman (Lyman 266469) and it casts a boolit that will fit my bore on my 6.5-06 just fine. Only thing is that the gas checks are real loose. Looked up this thread and found Felix' post on the gas check shank sizes. This 6.5 mm mould has a .241 X .242" shank coming out of this mould-both cavities. Dug out my .257 Gator checks and they squeeze right on! Outside mic's out at .265-.266 so the .265" sizer just touches them and the bases are flat. I've decided to just keep it the way it is. Sure takes alot of doing these days to get a boolit to fit!

So thanks again Felix.

[C.F.Plinker]

I am thinking about getting in on the group buy for the 41 Magnum NOE hollow point mold but I haven't decided on whether to go plain base or gas checked. . I have both a microgroover Marlin and a S&W model 57. As far as I can tell, neither Lyman nor Hornady makes gas checks for this caliber so I have two questions:

Who does make them?

Can I use a .416 check for this caliber in both the rifle and the pistol?