Undersized gas checks

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Last Post 10 June 2008

CBA Member

billwnr posted this 25 November 2007

Anyone got a good method to enlarge undersized gas checks.

I've tried three methods.

1) Annealing the gaschecks to make them softer and get them to fit better on the cases. Still scrapes the sides of the bullets

2) Using a punch to enlarge the gas checks. Makes an off center indent in the bottom of the gas check. May or may not affect accuracy. I do not know

3) Using a round headed bolt to enlarge the gas checks. Makes the gas check bullet concave and may prevent the gas check from being fully seated on the bullet.

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13 Comments

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Standard Member

JeffinNZ posted this 25 November 2007

I use method # 2.

Jim at CBE cuts his shanks for .303 Brit moulds a bit stout so I have to spread the GC's to get them on. Works a treat.

Kinda wish someone would make a .31 cal check though to save my efforts. Still, they would be twice the price for sure and GC's are far from cheap now.

Cheers from New Zealand

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CBA Member

giorgio de galleani posted this 25 November 2007

Usig methods 1 and three.

Just grind away a little of the round head screw not to get a concave gas check.

Regards, Giorgio

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CBA Member

RicinYakima posted this 25 November 2007

I use method #2, but made my own punch that just flares the edges and put a round handle on it. I can lay them out on a formica bench top and push down enough to flare the sides. Ric

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CBA Member

billwnr posted this 30 November 2007

I will be loading some ammo up with gas checks with the offcenter indents in them and shooting them on Sunday to see what the effect is. I hope this is a big “no brainer” and doesn't cause me to find a different method of enlarging the shoulders on the gas checks.

I am currently at a standstill with bullet production while I evaluate the gas check concerns.

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CBA Member

billwnr posted this 09 June 2008

I am using a 4th method that seems to work ok for seating undersized gas checks.

I acquired one of the round magnets seen at work to stick things up on white boards. It's about the diameter of a dime and just fits on top of my lubesizer.

I sit the bullet and partially seated gas check on top of the magnet and use the ram (and appropriate nose punch) to push the bullet down and seat the gas check.

Of all the methods I've tried this seems the easiest and best.

I've 1) chamfered the base of the bullet so it would enter the gas check, 2) heated gas checks to soften them, 3) flared gas checks with a punch, 4) flared gas checks with a round headed screw.

All methods seem to have their problems but using a flat surface as a “gas check seater” seems to be the best. It does give nice flat bottomed gas checks that are fully seated.

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CBA Member

Ken Campbell Iowa posted this 09 June 2008

First, determine the accuracy level you demand.

If you are not ( aiming at .. ) the top 4% of top level match accuracy ( loosely 1/2 moa with cast ) I would be trying various homemade gas checks ... and I would start with the wax wad types .... and firstly would try CFVenture Wax sheets, which you can buy and try ...CFVentures, 509 Harvey Dr., Bloomington IN 47403-1715.

the good news with wax wads is that are usually cut out of a sheet at loading by the case itself, and so the fit is pretty good... they wind up as a “pellet” behind the bullet base ... so you can also use them on non-gas-check-base bullet.

If the commercial CFV wads encourage you, it is not so far to trying to make your own ” grease wads” or ” wax sheets” ... melt your material on top of hot water, and then it cool and skim off your wax sheet.

One of the members here made a few years ago a neat gadget that would extrude grease wads in strips, so you could poke out your own wads ... not sure it is still available.

I have had some luck shooting ( hornady etc ) gas checks backward, make sure they go down and out the barrel EACH SHOT ... this works well for single shots, or a cleaning rod down the bore between shots .... before doing this stunt, I recommend annealing the checks so they will upset readily... the idea is to have them block the hot gases from getting around the bullet and stopping the leading before it starts.

Also of interest, and there has been much discussion on..... use of fillers to replace gas checks ... I think that ( that magic 1/2 moa ) accuracy has not been achieved with fillers, and certainly a lot of bulged chambers have resulted from this practice ... but still some are getting acceptable ( sigh ) accuracy consistently, and with no bulging or ringing SO FAR...here the idea is not only to get good ignition ( very very good ) but also to protect the bullet base from the erosive gases .....

I have recently ordered some bulk corn cob media to try as a substitute for CremeOfWheat , it is lighter and hopefully will not impact seriously the bullet after it leaves the muzzle.

Hoping that something above is of value, ken campbell, iowa

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Standard Member

JeffinNZ posted this 09 June 2008

billwnr wrote: I am using a 4th method that seems to work ok for seating undersized gas checks.

I acquired one of the round magnets seen at work to stick things up on white boards. It's about the diameter of a dime and just fits on top of my lubesizer.

I sit the bullet and partially seated gas check on top of the magnet and use the ram (and appropriate nose punch) to push the bullet down and seat the gas check.

Of all the methods I've tried this seems the easiest and best.

I've 1) chamfered the base of the bullet so it would enter the gas check, 2) heated gas checks to soften them, 3) flared gas checks with a punch, 4) flared gas checks with a round headed screw.

All methods seem to have their problems but using a flat surface as a “gas check seater” seems to be the best. It does give nice flat bottomed gas checks that are fully seated. Bill. Does you seating method cause any significant 'bumping'?

Cheers from New Zealand

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CBA Member

billwnr posted this 09 June 2008

It doesn't appear to. I'm only applying enough pressure to seat the gascheck. Brass is relatively easy to “move".

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Standard Member

jhrosier posted this 09 June 2008

I have a different variation of Bill's technique. I cut a shallow flatbottomed recess in a piece of 5/8” aluminum round stock. The recess is just a shade larger than the gas check. The piece sits inside the retainer ring on my Lyman 450, on top of whatever die is installed. I tried a piece of flat stock but couldn't seem to get the bullet in the center and my checks were angled. The recess keeps things lined up nicely.

My bullets are hard enough to resist bumping, water dropped WW+lino.

Jack

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Standard Member

CB posted this 09 June 2008

I just give the GCs a light touch with my arbor press with a rounded attachment. That seems to work for me.

Jerry

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Match Director

linoww posted this 09 June 2008

Have a “gc shank swage” made to fit you lubrasizer.I had one made and its faster to alter to bullet to the check as opposed to the opposite.You have to be careful not to “molest” the bullets nose,but it works good enough.In combo with annealed checks it is a good system.

George

"if it was easy we'd let women do it" don't tell my wife I said that!

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Standard Member

cityboy posted this 09 June 2008

I assume Hornady gas checks are being discussed. The BEST method for opening a 30 cal GC is to use a Lee universal neck expander die and the ram from a Lee sizer. The large expander is put into the die. Place to GC on the ram and raise it to the top position. The die is then ccrewed down until it contacts the ram. Back the expander off a bit; place the GC on the ram and raise it to the top position. Then screw the expander die down until you get the proper expansion. It works like a charm.

This is not my idea; I saw it in TFS.

city boy

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CBA Member

billwnr posted this 10 June 2008

Ken Campbell, Iowa wrote: First, determine the accuracy level you demand.

Hoping that something above is of value, ken campbell, iowa

Ken, I am not interested in a method that isn't accurate enough to pound the center out of a target. If I felt a method wouldn't produce top accuracy I wouldn't recommend it.

Undersized gas checks

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