A hazard from gas checks?

[wallenba]

I had a conversation with a knowledgable gunsmith and caster last week whose opinion I respect....but question a bit. It was about the 'hazard' of seating a gas checked boolit below the neck. I am forced to do this with a few of my loads just so they chamber. Also, the seating depth given in many cast loads in the Lyman hand book and others, do exactly that. I seat them out when I can. His assertion is, that the check can become dislodged when engraving the rifling, come off, and become an obstruction for the next shot. My own intuition tells me that the check could not stand up to the forces behind it, and would be blown out under ANY circumstance.

I'm not going to alter my loads, as I've never, in many thousands of shots, ever worried about it. Yet, I am a knowledge seeking type individual, and would like to know more about this if anyone has an opinion.

[Bill*]

My gut feeling says the same thing as your intuition. I don't see a check holding back that kind of pressure.

[largom]

By his "assertion" that the rifling could pull the check off what difference would it make where the boolit was in the case neck? I could see the possibility of an improperly, too loose, installed check falling off if seated below the neck but if it's in place when the powder ignites it's going out the bore with the boolit.

Larry

[wallenba]

By his "assertion" that the rifling could pull the check off what difference would it make where the boolit was in the case neck? I could see the possibility of an improperly, too loose, installed check falling off if seated below the neck but if it's in place when the powder ignites it's going out the bore with the boolit.

Larry

Perhaps he meant when the check met the bottom of the neck itself, and I took it to mean engraving the rifling. But I would think that the case neck would already have expanded under pressure before the boolit began moving forward.

[GOPHER SLAYER]

In a brief explantion to a qustion on the subject by a caster, the NRA said the reason you should not seat the gas check below the neck was because it allowed the hot powder gases to erode the bullet before it left the chamber. As for a primer being caught and sticking in the barrel, even discounting the powder, the primer alone would blow the primer out of the barrel. I know that because I have done it. I realized I forgot to put powder in a case after I had seated the bullet. When I pulled the bullet the gas check stuck in the case neck. I chambered the case and pulled the trigger. The case check made quite a projectle in my work shop. How did I know I didn't charge the round with powder you ask? The powder was still in the pan on my scale.

[btroj]

Yeah, and microgroove barrels won't shoot cast, wheel weights will wear out your barrel due to the dirt imbedded in them, and cast bullets must be hard to shoot well.

Any other old wives tales we want to discuss?

[uscra112]

"It's not that our opponents are ignorant, it's just they know so much that isn't true." (Ronald Reagan)

Never ceases to amaze me how often I see this adage proven.


Phil

[wallenba]

"It's not that our opponents are ignorant, it's just they know so much that isn't true." (Ronald Reagan)

Never ceases to amaze me how often I see this adage proven.


Phil

My first instinct was to argue against his warning, but he's a caster too. That does not mean he's infallible because he's a gunsmith. (His shop has done great work on three of my firearms in the last 16 months.) I think I'll just nod politely should the subject arise again. If he avoids loading that way, no harm to him, so it's not worth arguing the point. I might need his services again soon.
I never burn a good bridge.

[.22-10-45]

Hello, everyone. Perhaps he had a bad experiance, as I did when shooting my very first cast-bullet load.
It was early Spring of 76' I was getting ready to test my first cast loads in a Rem. 700 .222Rem. Bullet was the Lyman 225438..probably a WW alloy. I couldn't find any crimp-on gas checks in area, so bought the Lyman push-on type.
I was all set up on the 100yd. range..bore sighted & loaded first round. at the shot, I saw dirt fly at backstop & small hole near bottom edge of target paper..normal for the low velocity start load & eye-ball bore-sight. I am about to load another...when a little voice in the back of my mind (guardian angle?) suggested it might be wise to have a look thru bore?
Even after 36 years, I can still remember sitting there arguing with myself why I should do this...hadn't I seen dirt fly? And there was a hole in target paper! Besides, gun was all set up..if I pulled bolt..would probably be moved & next one would be out. Finally I gave in & had a look. Bore choked with powder smoke..as I blew it out, I took a quick peek...See just as I thought....But wait..what is that? kind of looks like a shadow? As I peer closer, there is a gas-check sitting in bore about 1" back from muzzle..edge-on to me..I nearly missed it!
Now I wonder, would the compressed air from ahead of next bullet fired blow it out? Or perhaps the bullet nose push it out? Or more likely, with my luck, it would be pushed aside & run over..ironing it into bore!
I have never had that happen again...But that was the last time I ever used a non-crimping gas-check.

[shotman]

I dont know about sticking in bore .BUT do know they will make history out of a crono when . they come off at 10 ft.
I just dont do it now

[tjones]

Ever think about these so-called PB checks made of .004 thick metal and rifling groove depths of .004 for the typical 30 cals.......duh. tj

[DukeInFlorida]

Swipe your finger quickly through a candle flame! Oh?? No burning, no pain???

I don't think the back end of a cast bullet, with some lead exposed inside the case, will see heat long enough to matter. The boolit will quickly be out of the case, sealed against the lands and grooves, and being pushed against by the pressure. No issues there. What really makes more of a difference with a cast boolit traveling down the barrel is the friction between the lead and the steel of the barrel, hence the need for a lubricant. And, also the hardness of the lead and the sizing of the boolit, so that the boolit gets the gases properly sealed behind it.

Your gunsmith's opinion is that the gas check will come off when it touches the lands and grooves? Every cast bullet gas check is the last thing to touch the lands and grooves. I don't get that logic, unless he's suggesting that the gas check gets pulled off hitting the beginning of the neck. Isn't the friction as the gas check comes in contact with the neck the same friction as the gas check sees when seated inside the neck area?

If the gas check is too loose to start with, I suppose there might be some potential for gas check to get pulled off as it contacts the neck area. I would shoot a few, and look inside the case after every shot, for signs of a loose gas check. Statistically, the more you shoot with no gas checks getting stuck inside the case will confirm that this is all a non-issue. My guess is that we all seat some gas checks that are somewhat loose, even if seated inside the neck area. I've never had one of the loose ones come off and get stuck in a barrel.

On the other hand, if you do find some loose gas checks, let us know.

I'm very surprised someone hasn't already studied this whole subject.

[GRid.1569]

I imagine the process to be: as pressure increases the brass of the case "moves away" from the bullet to create the gas tight chamber seal (the case is just a gasket of sorts during firing) - as the shoulder & neck have moved away; the leading edge of the Gas Check has nothing to catch upon before the bulet has started up the barrel....

....just as I see it....

[mold maker]

Unless the check has already fallen off, it will exit the barrel when fired. If it moves into the stream of pressure, it can't resist going with the flow.

[Ben]

I've shot a bazillion rounds with cast since 1967.
I'm certain that a high % of the rounds had g/c's seated below the neck.

Never experienced a problem.

Ben

[jhalcott]

I tried a bunch of Lyman "push on" checks years ago. Comparing them to "crimp on checks. Shooting thru a cardboard sheet at 15 yards, I got many 2 for 1 holes in the sheet. Meaning the checks came off quite often if not crimped on. I tried the same thing with checks below the neck on 30-30 ammo and shot into a Duct Seal target at 25 yards. Many of the uncrimped checks were missing. The bullet bases were often damaged a little where the crimped checks had good bases. I shot these loads at 100 yards for accuracy and the crimped checks always seemed to shoot better. This was with an OLD single shot 30-30 that I wasn't too worried about blowing up! Years later I tried some of the UNcrimped checks on 45-70 loads and got about the same results compared to crimped ones.

[Ben]

The original post said " and the g/c become an obstruction for the next shot."

The real question is.....Has anyone every experienced this and knows that this was the cause of the barrel obstruction ?

Ben

[felix]

If a block of snow within the barrel(s) can bulge the barrel(s), then probably a gas check or two will too. Yes, snow did cause an egg-in-the-snake look on two 20 gage barrels after climbing over a barbed wire fence with gun in hand (which is a NO-NO anyway). ... felix

It has to do with the rate of change of pressure. Not enough time for the rising pressure to clear the obstruction. ... felix

[Ben]

Felix :

Back to the question......Is there proof by anyone who can attribute a bulge in a barrel to a gas check that was seated below the neck line ( in a real life experience - not theories ) and knows that it also caused an obstruction in the barrel , then a damaged barrel with the next round that was fired.

In other words...who has proof that this has actually happened before as a direct result of a g/c obstructing a barrel ?

Felix, I'm not saying it can't happen, but I want to hear from the individual and hear their story on the subject .

I'm aware that snow and mud can bulge shotgun barrels. That is a fact. But....on the subject of a cast bullet with a gas check seated below the neck line of a case in a center fire rifle ....what actual proof is there that damage to a barrel has occurred before ?


Ben

[rbuck351]

If the GC was to fall off into the powder before being fired, there is a good possibility that it may not clear the barrel. If the GC is still on the back of the bullet as in still held to the back of the bullet by the neck tension, I don't think there is any way for it to not clear the barrel. Lots of pressure behind it with none in front. This is my guess as to why you should keep the GC in the neck. If you have a good crimp on check, I can't see it coming off in the bore whether seated in the neck or in the powder.