Put GC on PB?

[Will]

Does anyone have a way to put a GC on a PB boolit? I have a 311410 that I want to shoot at about 2000fps but it gets wild above 1600fps.

Will

[kodiak1]

Mighr be a little tough Will, There needs to be that inst at the bottom of the bullet for the gas check to go on.
A plain base bullet you would be trying to squeeze it so hard to get rid of the lead that has to be displaced for the Gas Check.
Ken.

[muffinman]

Will go to the castpics site I just read a article there lastnight about putting gas checks on plainbase boolits, looks pretty simple gonna try it this weekend. mark

[JSnover]

There are a couple of threads about flat gas checks; basically putting a washer under the PB boolit. A couple of guys had decent results but I got the impression it just wasn't worth it.

[Will]

The article in castpics is interesting. I think I'll give it a try.

[muffinman]

Yep, why not? Im not going to worry about making any tools till i try a few and see how they work. Let us know how yours turn out.

[44man]

I don't think the gas check will cure the accuracy problem.
What you can try is just put the check in the mold, make sure it is all the way down and cast a boolit right on it.

[Larry Gibson]

I don't think the gas check will cure the accuracy problem.
What you can try is just put the check in the mold, make sure it is all the way down and cast a boolit right on it.

That's kind of hard to do with a bottom pour mould.

Larry Gibson

[Larry Gibson]

Will

I've done it with several PB bullets that have sufficient taper to enter the GC. I use a GC seater and scrunch the bullet down in until the base bottoms out. I then run it throught the sizer to crimp the GC. Never tried it with 311410 but have done so successfully with a couple others.

Larry Gibson

[crazy mark]

I made a sizer die without any lube holes and the bottom part is the proper size for a GC on a 35 cal bullet and the top part is .359 so the boolit can't bump up too much. Using the right top punch makes it much easier. I lube the boolit first in a .358 die. Making one to do 30 cals shouldn't be too hard if one had the time. Mark

[beagle]

The problem with GCing a PB .30 is that it's hard to find a sizer die the proper size to swage the base band. Not everyone has one laying around.

Mark's idea is best if you have access to a good machinist.

It is possible to punch a hole in the GC from the convex side and cast through the hole. This does very well and the ragged edges on the hole tend to cast into the metal and bond the GC to the bullet. Float the punched GCs on top of the melt and pick them up with a pair of forcepts and drop them in the mould, straighten and cast. Works well for the 358430 195 grain and the .35 Remington. Also does well with the 45712X series of Lyman moulds for the .45/70.

If you mess one up, drop it back in in the pot and recycle./beagle

[beagle]

The 311410 may not do that well at higher velocities. I had factory HP mould once and tried it in the .30/30. Did not work for me. The 311410 has a fairly short bearing surface and this may be the reason. The best light bullet I've found is a 311465. That's been a winner in everything from the .30 Carbine to the .30/06 as a lightweight bullet./beagle

[44man]

It is hard with a bottom pour. But I made a punch to cut the center out of the check and it works fine. Just have to get it level with the top of the mold.
It's easy with my nose pour though.
I have also tried the check at various drive bands.
I did it just to see if there would be a difference and never found any over the PB in my revolvers.
Usually if a boolit shoots good at one velocity and won't if driven faster, the boolit does not match the twist at the higher speed. A different length boolit would solve it but I don't think just adding a check will cure it.
Unless of course the pressure is so high it is destroying the base. Hard to tell unless some are caught undamaged to inspect.
Here is one with a front check, hard base and a pure lead nose.

[Scrounger]

This is probably weird and unworkable, but... You know those inside/outside deburring tools Lyman and other companies make? I wondered if it would be possible to make/alter one of them to cut the gas check shank on a plain base bullet.

[felix]

Sizing dies would be faster and more appropriate, Art. I have requested they be made to order by Saeco several times, just like they (Redding brand) do for the neck sizing dies. Sizing rings in half thousands to be inserted into a mother die. ... felix

[black44hawk]

We folk are tinkerers by nature, however, in light of all that trouble I wonder what sort of velocity you could get with a simple wad?

[Scrounger]

You missed the point, Felix. I mean it to cut the lead away from a cast bullet like it cuts the brass in the case mouth.

[racepres]

Maybe this will help... drop me a note for more info.. MV
http://castboolits.gunloads.com/showthread.php?t=23276

[mroliver77]

So while we are here, do we really know what the gas check does and where in the barrel it does it? I have recovered many boolits with and without checks. It is amazing how the check is flattened and conforms to the boolit base. I guess I have never examined a plain base that was pushed to the point of failing.
J

[Poygan]

Buckshot recently made me an H die to put a taper on a .358 diameter boolit. I've tried it on an RCBS SWC and a .358429 and it seems to work just fine but I'm waiting for better weather to try some of the loads with it. The workmanship was great and the price was most reasonable.

[yeahbub]

I agree with CrazyMark and Felix. Having the boolit already in the die and perfectly aligned with the GC shank dia portion at the bottom would be a way I would trust to produce repeatable results. Actually, given a gently angled step from major to minor diameter, I don't see how it could mess up. A few years back, a friend and I made up a two-dia size die to bump the Lee C312-185-1R nose portion to the right dia for his rifle. Running the driving band portion into the minor dia was also no problem at all. A size die and heel post to match. Sounds simple to me.

Scrounger's idea of a cutter to skin the heel band down to GC shank dia would work also, but how would alignment be maintained? This suggests the need for other pieces of tooling to accomplish that part. In the past, I tried to skin some .430s down by lightly chucking them in a drill chuck and holding a file against the heel band as they spun, to get the dia down. It worked, but precise consistency wasn't my forte. A collet would have been a huge improvement over a drill chuck, but t'was not to be.

There is another low-cost low-tech gas checking technique for a Lyman 450 that worked well for me in the past, and it can be done on any flat base boolit that is several thousandths larger than the desired finished diameter. It involves a little machining, but only two pieces and doesn't use a conventional GC:

1. Machine some round stock (half hard 4140 or grade 8 bolt?) so the OD is a close drop-in fit inside the die retaining nut on a Lyman 450. Bore and finish ream a hole through the center .001-.002 greater than finished boolit diameter, deeper than .38", .50" will do nicely. Cut the end off the stock .25 -.38" long. Chuck it up and smoothly radius the hole edges (.06 is plenty) for an easy start for the boolit on both sides. I used a burr knife and polished with 400 grit sand paper. You now have a very short "partial sizing die ring" with a hole radiused on both ends.

2. Chuck up and counterbore the face of the Lyman die you plan to size with to .445 dia x .010 deep concentric within .003 with the sizer hole. I used .006 soft copper shim stock and this face will house the GC material in disk form centered on the sizer hole. Then, radius the entry hole on your sizer die (.010 approx), so tthe GC material will flow around it without being stretched much by going over an abrupt corner. How much is a matter of experimentation. It should provide enough resistance to smooth the shim stock onto the heel of the boolit without pleats and wrinkles, but not so much that the heel tears through it.

3. Buy or make a 7/16 punch to punch disks out of the copper stock. I punched them against smooth end grain wood which was ash, I think. I expect harder woods will be better for this. Lead would also work. The disk edges should not have a pronounced radius, since the counterbore on the sizer is only .010 deep and they would be hard to center. Whatever wire edge they do have should face upward so they'll become ironed into the heel band and help hold the check on.

Install the sizer in the 450. The way it works is put the copper disk in the counterbore of the sizing die, put the sizer ring on top and put the boolit heel in the hole and push the boolit through the ring and into the sizing die in one smooth motion, lube and eject. Remove the ring, center another disk on the sizer, replace the ring and you're ready to go again. The downward force exerted by forcing the boolit through the ring is to hold the ring against the sizer, keeping the disk flat rather than allowing it to bunch up into a "cupcake paper" and be wrinkly around the boolit heel. Depending on the as-cast dia, sometimes they did wrinkle up a bit, but I could tell no difference in performance. I also tried this with aluminum pop can material, but found that it needed to be annealed to result in a clean corner at the heel. This can be done with a torch, but I really didn't want any extra aluminum oxide wearing on my bore. I wanted to try some 7-UP cans, which used to be steel, but they had switched to aluminum by then. Might've been hard on the punch as well. Using .4375 dia copper disks will work well for .30 through the various 8mm's. These are a good bit cheaper than conventional GCs and can use a number of different materials. There's no GC-maker to build or buy, since the boolit itself accomplishes that. For those with access to the tooling it's a simple thing to do and isn't one of those 10-minute jobs that takes three days.