Author Topic: gas checks (Read 912 times)

kevin · « **on:** June 11, 2003, 04:58:22 PM »

Ok i'll be the first to admit I am having a blast making 162 grain rcbs bullets and to day i set up my lyman 450 luber sizer with the proper top punch and sizer die and plasing the gas checks on the bullet first really sucks os tried putting the gas check in the hole first then the lead and size the bullet ,and you know what that was fun and real relaxing, now here's a question what exactly does this small peise of copper or brass thing really suposed to do? in reading it says that when running the bullet at higher speed levels than you normally would do with plain based lead its subposte to help incase of lead build up by scrapping the rifleing clean is that really the case or is that just theroy?( spelling is lousy), any how it was a neat experiance and will keep'em cranking out.
Kevin

Leftoverdj · « **Reply #1 on:** June 11, 2003, 05:35:17 PM »

My belief is that the major function of the GC is to prevent melting and flamecutting of the base. (Yeah, I know about the Wilke GC. It prevents flamecutting.)

I base that belief on the observation that other methods of protecting the base which could not possibly have a scraping action also raise the velocity and/or pressure level at which leading occurs. These other methods include things like SoftCheks, cereal fillers, and GCs cut out of old rubber boots.

In fact, GCs can prevent leading when seated upside down. Very little scraping could be done with the radiused edge up.

Johm D M · « **Reply #2 on:** June 11, 2003, 07:15:40 PM »

Veral Smith of LBT claims that gas checks should be called driving cups or rotation cups as he feels that they put the final rotation on the bullet as the base enters the throat and prevent the base from stripping at engaugement. Add to this the scraping effect and the lube containment as the bullet tries to escape or outrun the lube I prefer them for all rifle boolits.John

Kragman71 · « **Reply #3 on:** June 11, 2003, 08:24:24 PM »

Kevin,
I admit,that I don't know exactly what that li'l piece of copper does for te bullet.
But I do know that the bullet needs it if it is moving fast enough. On the other hand,I don't see any advantage if the bullet velocity is low enough.
You did'nt mention your cartridge,nor the alloy that you are using.
Maybe you do not need the gas check.
Frank

hubbard · « **Reply #4 on:** June 13, 2003, 01:47:28 AM »

i have an rcbs 162 gr. gc 357 or 38 mould which is probably what he has..they shoot ok at low velocity without the gc. the gc seals the base of the bullet in the bore and keeps the expanding gases behind the bullet instead of letting it get between the riflings and the sides of the bullet. this will streak your barrel with lead.also protects the base from melting.

bfoster · « **Reply #5 on:** June 13, 2003, 04:46:17 AM »

At somewhere around 18Kpsi pressure Linotype will start to compress. This isn't much of a problem with many handgun bullets as the applied loads are at or below this level. But it becomes a significant issue in a rifle or hot handgun ammunition when the handloader attempts to produce relatively high velocities. In this instance, the gas check serves as a structural element of the bullet, in addition to performing the functions listed above.

Bob

Bug · « **Reply #6 on:** June 17, 2003, 07:12:43 PM »

We all know how important the base is for accuracy. Poor base = poor accuracy. But, what I'm wonderin, is how much will a gascheck make up in this area. Supposin' it's on square with the bullet, recon it'll take up the slack on those rounded-base buttets I SEEM TO BE SO GOOD AT CASTING???>>>>>>>>>>>>>Bug.

kevin · « **Reply #7 on:** July 02, 2003, 02:43:30 PM »

Bug I am in agreement, i have noticed that sometimes no matter how well you watch what your doing you somtimes get a gas check that will some how get off center and tilys after its sized and leaves me with a wonderfully crooked gas checked base well it will get shot as a plinker, oh well, Kevin