Gas Check question for .223 verses none on .22 magnum

[alsomontanamark]

OK, This is my first post, I have never cast a bullet, but I just recieved 1 for .223 in the mail. My possibly stupid question is ...... how come we can push a 40 grain bullet in a 22 magnum without a gas check to 22-2400 fps, but we need a gas check for our cast bullets in .223, 22-250, etc?

How fast can we really push our bullets before we need a gas check? Is it a function of weight verses cross sectional area (caliber)? And if so, is there a formula to use so I can calculate at what velocity I need to start using a gas check for a certain weight bullet in a particular caliber?

I guess an umpteenth question. How hard is the lead used in .22 long rifle and .22 magnum? It seems pretty soft, so why no gas check on the hyper speed ones, like lightning, thunderbolt etc, and .22 magnum as asked earlier. I suppose the use of gas check would somewhat depend on the aloy hardness that we are using, but I it seems like to me that the lead I will be casting for the .223 will be alloyed at least as hard as a .22 cartridge. The long rifle is used out to 100 yards in target matches with no gas check, very accurate, but of course the target ammo is going under 1200 fps.

It doesn't really seem like I have read articles on cast bullet shooting where people are pushing velocieties much faster than a .22 magnum at 2200-2400 fps. I have known guys that never clean the lead out of the barrels on there .22 long rifles, so I guess the gas check question is really in my mind as to weather it is necessary, if you get a mold with a flat based bullet where there isn't a ring for a gas check involved and shoot at velocieties under 2000 fps.

Well, being new, guess I have some sort of stupid questions, I'm sure this won't be the last post about greenhorn stuff.

Thanks: alsomontanamark

[runfiverun]

no it won't.
spend some time reading saami speccs on the 22 lr and 22 magnum rounds then compare those to the ammunition you have.
pull some bullets from each one.
and compare twist rates in their barrels to your ar barrel.

oh a 22lr is swaged from a @ 1.5% antimony and no tin alloy.

[Jack Stanley]

I think the only twenty-two ammo that does not use a jacket is Winchester Dynapoint and even them the bullet is of the plated variety . The velocity of most of the forty grain magnum ammo I've tried is about nineteen hundred feet per second . Depending on the fit of the bullet for your two twenty-three rifle and your powder and primer choice you might be able to match that without a gas check . A rough estimate of when to start using a gas check is sixteen hundred feet per second . You might make on the faster or slower side it depends on you and the rifle .

Stick around the subject of casting for the tiny bore comes up regularly .

Jack

[I'll Make Mine]

Actually, other way around, Jack -- most .22 LR ammunition is plain lead, either wax coated or dry lubed. There's some dry lube that looks like copper or brass (Mini-Mags, Yellow Jackets), and a few types of .22 LR that have a very light copper plating on the bullets, but nothing in .22 LR (that I know of) has anything we'd normally call a jacket. This ammunition, in the 40 grain bullet weight, is generally around 1250 ft/s for high velocity, a bit less for standard velocity (and there are a number of subsonic loadings around now, if you can find 'em). Now, .22 Magnum is divided; some loads have jackets, some don't, but those are the ones that might give 1900 ft/s, not the LR.

To the OP, how fast you can push a bullet without a gas check and avoid leading depends on a number of factors, most important being the fit (must seal the bore; gas escaping past the bullet will melt lead at the escape path that then deposits in the bore) and hardness (other factors equal, harder bullets will resist skidding in the rifling better than softer ones, so can be pushed a little faster before they give trouble). Some folks using carefully chosen alloys, good fit, and the right powder can get bullets up to around 2000 ft/s without a gas check; others get leading at 800 in a pistol.

[Jack Stanley]

I was refering to Magnum ammo such as the Dynapoint is plated and much of the rest of the magnum line uses a jacket . My apologies , I re-read my post and I can see how one might think I was refering to all twenty-two rimfire ammo . I was sure the magnum ammo runs at nineteen hundred feet per second in the forty grain lineup .

Jack