Reversed Gas Checks

[Nelsdou]

While cleaning up the shop one day I gathered up a number of gas checks I peeled off of some 8mm reject cast boolits. I never throw something like that away and thought about some 8mm plain based 150 grain plinkers I cast the previous week in Lyman #2 air-cooled. They were off a mould I bought in a Cast Boolits group buy.

They fit my Mausers and shoot well over a light charge of Unique but are limited to just plinker speed.

For a lark, I took the gas checks, put 'em reversed on the punch, plain-based boolit on top w/ lube and ran the ram up through my Lee sizing die at .325.  Then I seated the boolits into 8x57 brass with the same GC reversed fasion and seated the boolit only partially down the case neck to retain the GC in the case neck and not dropped into the case body. Kind of tricky to handle the boolit and gas check this way; definitely bell the case to help get things started.  This was done over a charge of 25.1 grains of AA5744.

For my next range trip I drug along a Yugo M24/47 that is my cast lead test bed. With my other shooting done I got it out and chucked several of the reversed CGs loads into it.  Really didn't expect much.

Lol and behold, I printed some pretty good groups with that combination!  Bad thing was they printed about a foot higher on the target then I expected at 100  yds. My guess the velocity is humming right along but wouldn't dare putting these over a chrony because of the loose gas checks.  On the other hand I didn't find a single gas check on the ground between the muzzle and the target afterward.

To make sure this isn't a fluke I plan to load up a few more of these and re-adjust my POA and see if I can get a good print into the bull.  Pics  to follow.

Nels

[recoil junky]

Sounds right intrestin' Nels. Must be working kinda like a minnie ball and sealing the gases thatta way.

'Bout the only thing I use gas checks for any more is for making shot shells. I've got 2 gas check molds, one for the .357 and one for the 44 mag. I want to try one for the 45-70, but I'm having such good luck with the plain base 457124, I can't bring myself to spend $60 for another mold. :D

RJ

[gitano]

Hmmm...

Paul

[Nelsdou]

A couple of pics of the bullets and Hornady CGs that I'm working with.
 

 

[Alboy]

iNTERESTING
 
If you have bullets made for gas checks how about a spot of super glue and two GC's oback to back to ease the handling problem some or will that just make it even more tedius?

[gitano]

Not a bad thought Al.

I wuz wunderin' how "things" were working, but now I think I see. The ram fits inside the lip of the reversed gas check. I couldn't figure out how it wasn't crushing the reversed gas check lips.

I like the concept of a "Minie' " rear end on a gas-checked lead boolit. It might be worth considering manufacturing a "double-cup" or "skirted" gas check when I start making bullets.

It would certainly be for "slow" bullets though. I would think that above the speed of sound, the drag due to turbulence at the rear of the bullet would be significant relative to even a 'plain' flat-based bullet to say nothing of a boat-tail.

Paul

[Nelsdou]

A malleable  "skirt" is a good way to describe it.  I'm not sure a second GC to a GC'd bullet would really gain much more over the one already there, however, it could be experimented.

Because of the drag, I wouldn't glue a GC. Pressure will keep it against the bullet base until it leaves the muzzle. After that its function is no longer needed.

On the plain based bullets I wonder if the copper skirt acts like a stiff wiper ring, keeping the pressure from playing mischief around the bullet base edges that ride in the barrel grooves and thus keeping the bullet center of rotation more true to its center of gravity.

More to come.

Nels

[drinksgin (deceased)]

I shoot a lot of gas check bullets, early reports of checks hitting chrono screens encouraged me to make a .295" lexan shield that I installed in front of the screen, so far, it has collected 7 checks with no damage to the screen.
I also replaced the metal sky screen supports with hardwood dowels from the hardware store, only one has bitten the dust, when I was shooting a pistol, not my long suite.
,

[22hornet]

Good post.

I shoot 160gn factory hard cast bevel based projectiles in my .308 for some fun. I keep the velocity low and no problem.
Maybe this reverse gas check thing might help.......

[Nelsdou]

My last session on reversed gas checks on plain-based cast bullets went awry.  The eyeballs just can't focus on those barelycorn Mauser sights anymore.  I used to be able to get in at least 20 minutes or more but can't even get that anymore.  Time to move on to a scope or maybe a good peep setup.

Best I could I sent 20 rounds downrange at a 100 yd target and they all cut paper true with no keyholing. This set was 23.0 grains of SR4759, Fed 210 primers. Not a speck of leading evident in the barrel on cleanup.  I'll play with this some more once I get some optics setup on one of my 8mms.

Nels

[gitano]

http://www.midwayusa.com/browse/BrowseProducts.aspx?tabid=14&categoryid=18260&categorystring=10611***686***10508***

I don't know if you use glasses or not, Nels, but if so, you might consider one of the items listed above. I bought the Lyman, and am satisfied with it. I suspect the Merit would work in wider lighting conditions.

Paul

[Nelsdou]

Thanks for the tip, Paul. I'll gin up a makeshift setup on a spare set of non-prescrip glasses and see if it's viable.

Nels

[gitano]

I used electrician's tape for a while, and finally just broke down and bought the "factory" one. I have not found it a panacea, but it is certainly an improvement. I read something today about keeping the left eye open BUT obscuring it with "frosted" tape. Supposedly, this prevents the aiming eye's pupil from dilating and undoing the effect of the peep-hole. I intend to try that and see if it improves the peephole even more.

Paul

[Nelsdou]

I taped an abrasive cutoff wheel from a Dremel tool onto the aiming eye side of a plain pair of glasses.  It has a fairly sharp edge aperture of about .080 inches.  It did give me some measure of improvement. Keeping the left eye open while aiming does require some retraining of the brain to bring the aiming eye into dominance.

Something like that Merit where one could change aperture sizes would be good; .080 sounds small but going down to .060 might work even better for me.

Nels

[gitano]

I've always kept my 'off' eye open when I hunt, and I taught my kids the same, but rarely do when I shoot at the bench.

The Dremel tool disk was an interesting solution. I never thought of that.

"It did give me some measure of improvement."

That's about my assessment. I seriously doubt there is a complete fix to just plain ol' old eyes. I am curious about the new aiming device mentioned here though: http://www.physorg.com/news192299313.html

Paul