Problem seating Plain Base Gaschecks

So, I recently decided I wanted to add a gascheck to a .311 bullet that I had designed some years ago for the 7.62x25, which I now want to use in a rifle in that caliber at higher velocity. Intended velocity is between 1600-1800fps. I looked on Sage's website and found they do in fact sell plain base checks for the .30cal. So I ordered 500 of these to try out with this boolit. However, after some experimentation I have found a few issues with it. And I'm hoping someone has some advice for me.

So first off, I was left a little underwhelmed by the plain base checks. They all appear to have tears in the skirt, as well as being slightly uneven in skirt height. I haven't shot any yet, so I'm not certain how much if any this affects accuracy. I just figured these would be a little more uniform, having used their standard gaschecks in the past. I could just be making a fuss about nothing here, it's just an observation. Now to some general measurements. Where it comes to the outer dimensions of the check itself the flat portion of the base measures approximately .3090" of an inch, followed by what I would consider to be a fairly large radius which widest part is approximately .3205", with the top of the skirt measuring about .3315". As to the inner dimensions, the best I can tell is the base is approximately .2960" tapering up to approximately .3150".

As for the bullet, this is a custom design I had make about 14 years ago by Mountain Molds - an older picture of the bullet below for reference. It's pretty similar to Accurate's 31-085G, though the dimensions are not exactly the same. This boolit drops at about .3115, and is powder coated using Smoke's powder. This brings the diameter to approximately .3125-3135" depending on how thick the powdercoat is. Picture for a reference:

https://castboolits.gunloads.com/att...4&d=1345330631

Now for the issue I am having, seating these things squarely... So I have tried seating these things in both a Lyman 4500 with a (RCBS) .311 sizer (my bore on the rifle is .310"). As well as a Lee .311 bushing mounted in a breach lock press with the adapter. The problem is that I have a high rate of unsquare checks, or deformed boolits. In the Lyman press, due to the nature of the gascheck being about .320", the check doesn't center itself in the seat of the sizer - this is an older sizer without much of a taper at the top. This can be centered slowly, and manually, but often results in the nose of the boolit being slightly canted due to the radius on the inside of the check not allowing the bullet to seat very squarely. In many cases this leads to boolit deformation. Which as you guessed, is undesirable. When using the lee push through bushing, the real problem seems to be an issue of getting the tiny bullet square while entering the sizer upside down. Which causes the check to cant to one side or the other - i.e., the boolit is longer on one side than the other due to an imperfect seat on the check. If sizing nose first this seems to be little less of an issue, but creates an uneven rim on the base of the check - due to the punch being a smaller diameter than the bore of the sizer. Again, not desired for accuracy in a rifle I would think. But as a note, this also isn't entirely square, as I can see a small but noticeable difference in how high up the skirt sits on the boolit.

Now, I do not have a proper top punch for this bullet, I don't think Dan offered them back when I ordered this, or if he did I didn't receive one with the mold. So I have always used a flat top punch when sizing in the Lyman 4500. This hasn't ever been an issue when sizing the bullet on it's own. But when trying to square the nose with the base when seating an oversized check this is what I feel is causing deformation when using the Lyman sizer. As for the Lee bushing, I feel it really comes down to the bullet being tiny, my fingers being fat, and trying to balance the bullet on it's .184" nose when using the punch that has a certain amount of play.

Now, I did read the instructions for the gaschecks. I've also seen where it is suggested to chamfer the base of the bullet so they see more uniformly, something a little difficult to do with a bullet only being .510" long. If I'm super careful, I can get about a 75-80% rate of usable boolits when using the Lee bushing and sizing base first. But that is still a lot of wasted checks and bullets. Not to mention pretty slow going. Does anyone have any advice?

I really can't be much help at all with most of this but read your post and it seems that a correctly fitting top punch would help. If you have a top punch that the bullet nose fits into is it possible that you could use a mould release on the bullet and epoxy in the nose/top punch to make it fit the bullet nose exactly? You would of course have to line the bullet and top punch up exactly to do this but a simple piece of plastic rod or steel rod drilled/bored to suit the bullet and nose punch would do that then make the epoxy nose form.

If memory serves theperfessor used to make nose punches that way. Here are a few links that describe what he did:

https://castboolits.gunloads.com/sho...s-the-easy-way
https://castboolits.gunloads.com/sho...ch#post1592016
https://castboolits.gunloads.com/sho...se-punch-trick

If you don't have a lathe it may be difficult to make a jig to line up the bullet and top punch... or maybe you coult push a bullet part way into your sizing die then lift the top punch, fill with epoxy, put mould release on the boolit nose thne lower the top punch.

Once done you shouldn't have trouble with the boolit canting as you size though the radius in the GC may still cause a bit of grief.

Anyway, just a thought.

Good luck!

Longbow

You could try to force the seat flat onto the base of the bullet using a gas seater system. You could buy an NOE gas check seater die and the appropriate top punch to try to force it fully on. Then run it through your sizers to see which one works better. It might work better nose-first in the Lee, if you squish the check fully on there, first.

To test out if this will even work, you can try it manually, first, seeing if you can tap the gas check fully flat onto the base with a small hammer. You could hold the bullet with pliers with the nose against your bench, or rig up a fired case to hold the bullet after filling the inside with epoxy so that the bullet only goes into the mouth deep enough to hold it securely while you tap the check on.

Whether this works or not kinda depends on how thick and properly shaped the gas checks are.

There are also potential methods for swaging a proper fitting gas check shank onto your bullets.

Quote:

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Originally Posted by longbow

I really can't be much help at all with most of this but read your post and it seems that a correctly fitting top punch would help. If you have a top punch that the bullet nose fits into is it possible that you could use a mould release on the bullet and epoxy in the nose/top punch to make it fit the bullet nose exactly? You would of course have to line the bullet and top punch up exactly to do this but a simple piece of plastic rod or steel rod drilled/bored to suit the bullet and nose punch would do that then make the epoxy nose form.

If memory serves theperfessor used to make nose punches that way. Here are a few links that describe what he did:

https://castboolits.gunloads.com/sho...s-the-easy-way
https://castboolits.gunloads.com/sho...ch#post1592016
https://castboolits.gunloads.com/sho...se-punch-trick

If you don't have a lathe it may be difficult to make a jig to line up the bullet and top punch... or maybe you coult push a bullet part way into your sizing die then lift the top punch, fill with epoxy, put mould release on the boolit nose thne lower the top punch.

Once done you shouldn't have trouble with the boolit canting as you size though the radius in the GC may still cause a bit of grief.

Anyway, just a thought.

Good luck!

Longbow

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I had forgotten about this. That may actually be a decent option. I've got a top punch for a 45 flat nose that I typically use. I don't lubrisize the .45 any more, just powder coat. So that may be the ticket. I'll break out some hot glue and test this.

Is your boolit plain base or sized for a gas check?

I have problems getting gas checks to seat properly with my Lee size dies. There is just not enough friction to properly seat the gas check on the boolit shank. What I do is seat checks on my lyman 450, then size with the Lee push through dies. Takes a little time to do but results in much more square checks on the boolits shank.

Quote:

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Originally Posted by Slugster

Is your boolit plain base or sized for a gas check?

I have problems getting gas checks to seat properly with my Lee size dies. There is just not enough friction to properly seat the gas check on the boolit shank. What I do is seat checks on my lyman 450, then size with the Lee push through dies. Takes a little time to do but results in much more square checks on the boolits shank.

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These are gaschecks for plain based boolits.

That is what I was initially trying to do, seat them on the Lyman, then size with the Lee sizer bushings. But it just wasn't going to work. So, it's looking like this particular boolit with gas checks is going to need to be sized only in the Lyman - unless I figure something else out.

I just mixed up some JB Clear Weld, placed it in the cup of the 45cal top punch, and let it partially cure before installing in the sizer, placing an already sized bullet in the .311 hole and resting the top punch on top of it. I let it cure for a few minutes before pulling out the top punch, removing the bullet, adding a drop of oil, and placing the bullet back into the top punch upside down in my vice to let it fully cure. We'll see how well this works.

I suppose if nothing else I could possibly do these in stages on the Lyman. Like seat with a .320ish sizer, then size with a .311. That might work better.....

Have you seen the NOE gas check seating tool? It does a number of things but one is complete square tru and completely. Its a die and used in a reloading press like a arbor. With top punches for noses. Here is three videos. Two of my friends have made and last is one of my own.

https://youtu.be/N2RA6M_W4YY?si=gdBp4t1uKzqD_sWv

https://youtu.be/Wwaw0kqNJRY?si=UkiEsw87hs_INRzt

https://youtu.be/ESe8nPaA6go?si=rMxvpQGTh1hzF_eh

There i also a number of plane base check makers/installers. I have one from a little ahop in Florida Matteson Machine.

CW

Hmm, well I'd start by trying to open up the gas checks themselves. You could use your 4500, take a piece of bolt slightly smaller in diameter than the diameter of your center punch, place it under your die to raise the center punch out. Then put your gas check on the die top and use a flat top punch to press the gas check over the punch, which should open the GC up to the diameter needed for your bullets to press in. Then you should be able to size them as normal in your lube sizer.

If you look at the center punches in your sizer, you might find that one slightly larger than the one you intend to size bullets to will have a base that is correct in diameter with a slight bevel, and if reversed, would work as desired.

I have a 35 cal Pat Marlins PB GC maker and I use soda cans for the gc's for plain base .357 Mag. boolits (works fine for 9MM also). I seat the gc's with my Lyman 450 and agree its a real PITA to seat them because you can't center the boolit over the sizing die with the un-sized gc on it's base. My solution: take a regular old 1/4" flat washer which has an OD of .625" which fits perfectly inside the nut holding the H&I die in the Lyman 450. I drilled (and then ground and sanded) the ID of the flat washer to .395" so that the boolit with un-sized PBGC on its base would be exactly centered in the sizing die for the sizing stroke. Works for me. Note: I just happened to grab that PC'd 356402 for and example.

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The gas check seater is another good suggestion by cwlongshot!

Here are a couple of threads on home made solutions:

https://castboolits.gunloads.com/sho...ect-every-time
https://castboolits.gunloads.com/sho...er#post1503783

That might help with the radiused corners if everything is aligned and seated hard the sharp edges at the boolit base may confrom better and the thin check material may also bend a little tighter to suit the boolit base.

If that epoxy nose punch doesn't work a seater would be the next easy step.

Longbow

If I read the Ops post correctly, he is powder coating THEN applying the plain base gas check. This results in the bullet base being a tad bigger than on a bare bullet. This may make it harder to seat and evenly install the gas check. I have used plain base gas checks with very good results, but I apply them on bare bullets.

Maybe the results would be better if the Op would try applying the gas checks, then moving on to powder coating. I have heard of others that have had good luck doing it that way.

Sam Sackett

I used to make and sell plain base gas checks here. I did offer 30 cal as well as others. Made from pop cans and could be used on up to .312 bullets. best used with a push through sizer but,be could be used in the other sizers too. They were popular and many thousands were made. I do have some left from some years ago. PM me and I can send you some to try. n.h.schmidt

Thanks for all of the responses. I have made and done an initial testing of a better top punch to keep the bullet more centered and square in the Lyman Press. I am going to be powder coating some new bullets this evening to test this, and if it works I'll probably stick with this solution.

As for the NOE die, I have seen that before. Although this wasn't previously an option, as I didn't have a top punch to use. Since I have now made one, this may be an option in the future if using the Lyman 4500 doesn't work. But there's no need in spending another $40 if what I have is going to work...

Ed_Shot, that's actually a pretty ingenious idea there. I'll keep it in the back of my mind. Thanks.

Quote:

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Originally Posted by n.h.schmidt

I used to make and sell plain base gas checks here. I did offer 30 cal as well as others. Made from pop cans and could be used on up to .312 bullets. best used with a push through sizer but,be could be used in the other sizers too. They were popular and many thousands were made. I do have some left from some years ago. PM me and I can send you some to try. n.h.schmidt

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Thank you for the offer. I'll send you a PM. I'm looking at a Power Pistol load for the 7.62x25 that shows in Gordon's Reloading Tool should be able to get this bullet up above 1800fps with my 18" barrel. So I'm interested in doing some testing. I'm not sure what a 30cal 90gr FP at 1800fps will do when it impacts. But it'll be interesting I'm sure...

Quote:

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Originally Posted by Slugster

Is your boolit plain base or sized for a gas check?

I have problems getting gas checks to seat properly with my Lee size dies. There is just not enough friction to properly seat the gas check on the boolit shank. What I do is seat checks on my lyman 450, then size with the Lee push through dies. Takes a little time to do but results in much more square checks on the boolits shank.

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This I do also and it's worked well for me.

Sorry to insert a question into this thread, but here goes anyway: I ran across some old "pistol checks" in a stores rummage bin and I'm wondering what they are designed for. One box is .38 caliber and a second is .44 cal, round copper disks (no shoulder), thicker than a typical gas check (haven't measured them but less than a penny thick), in boxes that are obviously new, old stock. Can't find any info on the web, hoping an old timer might be able to help me. The only thing I can think of might be to place then in the base of a bullet mold before casting, more than likely under a bullet not designed for a gas check, but I'm not sure that would give a consistently good result. Anybody have any ideas about what these are designed for? Suggestions welcomed!

I didn't take the time to read the entire thread and maybe someone has suggested this. I always install plain based gas checks by running the bullet and check through a Lee size die base first. I've never had a problem. I do use a RCBS lube machine and also have a couple of Lymen machines but I don't do any sizing with them, only lubing. I size in a Lee push through and then lube in the machine with a die .001" larger than sized diameter.
Good Luck,
Rick

If you really care to sink some time and elbow grease into it, I found a way to make gas checks fit, perfectly. I posted some pics, somewhere in this subforum.

Drill and file out a hole in 1/8" plate of steel to make a bullet sizing die that only sizes the last 1/8" of the base of the bullet. Then use your top punch to push the bullet into this chamfered hole. Now you get the check to fit perfectly, and you can even form a lube ring in front of the check.

What I did is attach this to the ram and install a top punch into the press, so I can just run my boolits through quickly. And the primer arm pushes the sized bullet back out of this sizing die. So it adds a step, but I get perfect checks. I use this to install "real" checks onto plain base bullets, not the soda can stuff. 9 thous thick.

Quote:

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Originally Posted by rocknrollgen

Sorry to insert a question into this thread, but here goes anyway: I ran across some old "pistol checks" in a stores rummage bin and I'm wondering what they are designed for. One box is .38 caliber and a second is .44 cal, round copper disks (no shoulder), thicker than a typical gas check (haven't measured them but less than a penny thick), in boxes that are obviously new, old stock. Can't find any info on the web, hoping an old timer might be able to help me. The only thing I can think of might be to place then in the base of a bullet mold before casting, more than likely under a bullet not designed for a gas check, but I'm not sure that would give a consistently good result. Anybody have any ideas about what these are designed for? Suggestions welcomed!

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Howdy and welcome to the forum. Sounds to me like copper disks that would be placed under the bullet when seating similar to a fiber wad when loading black powder. I'd love to see some pictures of them. I've never heard of anything like that.

If you powder coat then bake nose down in a hardware cloth 1" deep upside down box, holding the bullet in the holes, base up, you do not need a gas check up to 2,700 fps. Repeat, You do not need a gas check to 2,700 fps, period. The bullet base is the key to accuracy and if the bullet base is screwed up so is your accuracy.
Powder coating and baking with the base up, produces a near 100% perfect base.

I use my own 45 cal PB GCs on rifle and pistol cast bullets to be sized from .451 up through .4615. I've found the seating and sizing can be difficult depending on the hardness of the bullet and/or the amount to be sized. Thus, I size, either with Lee push thru's or 450 lubrasizers, in stages of not more than .002 sizing at a time especially with the harder bullets. Doing so I have been 100% successful. Not doing so results in mal formed GCs not seated well and deformed bullets. .