New source of gas check material for those who roll their own...

[Cap'n Morgan]

Well I got the forming button inside this thing & managed to pop out a few cups. They are sticking inside my female forming die, so I needed to dig them out with a small screwdriver. I'll either need to get a stronger die spring or I'll need to add a solid pin to push the finished parts out of the die.

Jim,

You could copy the plunger/ejector idea from the tool Kaj made:

http://castboolits.gunloads.com/showthread.php?t=31987

BTW. Smart move making the die concave instead of the punch.

[JIMinPHX]

I don't know how I missed this. I don't know how I got it into my head that gas checks should be 0.010" thick. .30 cal gas checks are more like .016" thick & .22 cal checks are more like .008" thick. I don't have any others to measure.

When the .010" aluminum checks fell off the shanks of my .30 cal boolits, but the .016" thick brass check seemed to fit like a glove, I started measuring things & found that .010" was not enough wall thickness to bring the boolit diameter up to where it needed to be. That's when I found my error in planning.

I also dug around in the McMaster book a little more & found that if I stop calling my copper "sheets" & start calling it "shims" that I can get .015" annealed alloy 110 pure copper. It ain't cheap, but it's about 1/3 the price of commercial checks.

It looks like I'm going back to looking for those beer bottles that AZ Stew told us about. Those things are looking better & better to me all the time.

[JIMinPHX]

Jim,

You could copy the plunger/ejector idea from the tool Kaj made:

http://castboolits.gunloads.com/showthread.php?t=31987

Wow, Pat did it. Kaj did it. I'm way behind the curve here.

Thanks for the tip off Captain. There are some nice ideas in that design.

I basically had one of two things that I was planning to do for better ejection. The first was to add a small spring loaded piston & use the top of the piston as the bottom of the forming die. This would give me room to use a bigger spring to get more umph. The second idea is more robust. I was going to add a cross pin that pushes up on a center piston under the finished check. The cross pin would hit a stationary block or sleeve when the press was moved to the down position & that would give you the entire force of the press to remove the finished check from the die. I picked up a few springs today, so I'll probably try that route first.

[rebliss]

After seeing Pat's set-up, I have abandoned any misgivings about wanting to create my own punch and forming dies. However, I still may decide I want a separate punch capable of knocking discs out of thicker material.

[JIMinPHX]

Bud bottles work!

BevMo had them, just like Stew said. They ain't cheap @ about $6 for a 4 pack, but hey, for research I'll go the extra mile. With a diameter of about 2-5/16" & a straight section of about 6", I should get enough material to do about 170 .30 cal checks per bottle. That's less than $0.01 per check including the price of beer, compared to almost $0.04 per check for the factory ones.

The checks look good, except for the screw driver mark where I dug them out of the mold. As soon as I make up an improved ejector, that mark should be a thing of the past. The checks seem to fit well on a Lee 150-grain FP. Both the brass & aluminum checks that I made on my gizmo look to be slightly shorter than factory checks. I had stayed with .375" diameter disks before forming so that I could make my punch out of readily available 3/8" drill rod (W-1). A slightly larger disk diameter would have mimicked the factory checks better, but I'm going to shoot these first & see how they do just the way they are.

The aluminum bottles look to have been made by the same process that is used to make seamless high pressure cylinders for things like scuba tanks & fire extinguishers. It's a real brutal process where they start with a small billet of aluminum & basically just mash it in a big die press to extrude the slug into the shape of the tank body, then they roll form the neck & top. It's kind of amazing to watch.

Anyway, here is a picture of the Lee flat points with factory copper, beer bottle, & brass checks.

[trevj]

If you got a wife in your life, look at the hair care products that she uses. Mousse, particularly, usually comes in an Aluminum pressure vessel, quite a bit thicker than pop/beer cans.

My plan for my version of the forming tool is to have the clearances set up so that it is a one way trip through the die to form, and to have the check spring out a bit on the far side, so it comes off the mandrel on it's return through the die. Seems to work OK on my hacked together test rig on the lathe. Was considering using a die ejector spring, rather than the ejector rod in the primer groove on the press, too.

I ran somewhere close to a thousand blanks out of aluminum flashing last night, while watching a video.
Process was to run a strip of holes down each side of the sheet stock, trim off the holes with a pair of scissors, repeat. 43 holes per side, 3 rows of holes per inch of width of material. Cost, a bit under $2.

Shim stock. Marvelous stuff! Pretty much any thickness you need, though a little pricey compared to some. Nice to have the options to pick from!

Cheers
Trev

[JIMinPHX]

After seeing Pat's set-up, I have abandoned any misgivings about wanting to create my own punch and forming dies.

Where can I get a look at Pat's rig?

[sheepdog]

Is someone building the punches to punch these out or does someone has the schematics to build one yourself?

[JIMinPHX]

Is someone building the punches to punch these out or does someone has the schematics to build one yourself?

I'll post a set of drawings when I get my final version worked out.

[rebliss]

Where can I get a look at Pat's rig?

http://castboolits.gunloads.com/show...=31005&page=13

[JIMinPHX]

I got a little lazy tonight & didn't want to do the extra work to make up a proper check ejector just yet, so I tried a few quick & dirty tricks. I shimmed my ejection spring up with a spent rifle primer to give it a little more umph & I smeared the bottom of my stamping material with a little case lube. That reduced the sticking to the point where removing the finished checks from the female die only takes a gentle tug. I'm sure that if I did a little more work, I could get them to jump right out of there by themselves, but for now, this is good enough. I punched out over a hundred checks tonight. If I want to do many more than that, I'm going to need to drink another beer.

Now I need to shoot some of these things.

[JIMinPHX]

http://castboolits.gunloads.com/show...=31005&page=13

I think that mine has a few advantages over his version. Mine does both the cut out & the forming in one step. Changing to a smaller caliber gas check only requires changing two small pieces, not the whole rig. Once I get around to making up the ejector that I have in mind, that task will take care of itself too with no need for the operator to provide any extra motion. The down side to mine is that you need to precut the strips of punch material to between 3/8" & 1/2" wide before you start punching. On either of the other two rigs that I looked at, you can probably just stick any old edge of a metal sheet in the slot & start punching away.

Thanks for the link.

[JIMinPHX]

I wanted to test these things out on the SKS, but all the SKS boolits that I had were already wearing copper checks. I tried prying a few copper checks off, but that left the boolit shanks too small in diameter for the new aluminum check to grab on well. I went to plan B.

I grabbed some 150-grain Lee flat points that I had kicking around & loaded them up for my 30-30. Since I already had some plinking loads sitting on the shelf with copper checks over 8 grains of Unique that I could use as a control group, I duplicated that load with the aluminum checks. The average velocities between the two types of checks only varied by about 4fps. The averages were a little over 1300fps. Extreme individual shot velocity variation from the entire two batches of ammo was less than 50fps. One 5-shot group from the copper & one 5-shot group from the Aluminum are pictured below. Can you tell which is which? The squares are each 1". These were shot at 20-yards from a standing position with no rest & no sling. I found no leading in the barrel. 10 rounds of the aluminum checked boolits were fired last.

[JIMinPHX]

These are the recovered boolits & gas checks.

[JIMinPHX]

I've been wondering about the new Budweiser aluminum "bottles" since I first saw them in a TV ad...
... those who know the homemade gas check business better than I, due to first hand experience, can comment on whether this is a good source...
Comments??
Regards,
Stew

Well, I guess that now that I've gone & done all this, I probably qualify as somewhat "experienced". I still need to try these things at higher speeds to see if the performance keeps up with copper at the high end, but from what I have seen so far, aluminum beer bottles look like a first rate source of gas check material, at least for the moderate velocity loads. I think that all my plinkers will be wearing aluminum butt caps from now on.

Thank you Stew for the tip off.

(ya knew that the little beer mug totin' smiley face guys had to come in here somewhere....right? )

[JIMinPHX]

I put a little ejector piston inside the forming cup. Now the finished checks pop right out. It's time for me to start drawing this thing up.

[angus6]

How's the drawning coming

[Slow Elk 45/70]

JIMinPHX, ok, we are waiting with great expectations, and thanx for sharing

[poisonivie]

The downside is the Bud beer, it is HORRIBLE.

come on now, suck it up and drink. take one for the team.

[JIMinPHX]

Just a quick update on using aluminum for gas checks...

They worked fine in my old 30-30, but they fouled the living daylights out of a rifle with a chrome bore. Apparently, aluminum & chrome don't like each other too well.

I still don't have my drawings done yet. I do have some ideas for some improvements though. I just need to find the time to get back to this project (after I finish a few others).