A hazard from gas checks?

[geargnasher]

I'm in the "never had an issue with seating below the neck" camp, but that means nothing really, maybe I've just been lucky. I wonder how many errant checks have been shot out of barrels without any issues except perhaps an unexplained flyer or two.

I DO feel the need to remark on Duke's statement about the lead melting wive's tale. The hand-through-the-candle-flame analogy isn't accurate. It isn't heat that damages or cuts boolits, it's gas pressure. If you pass your hand quickly through a 30,000 PSI air jet, it will cleanly and instantly slice off your fingers. Gas-cutting can and will occur at any point that there's an obturation failure (gas leak past the boolit). There usually isn't a sufficient pressure differential to cause a rush of powder gas to damage any portion of a boolit seated below the neck. Sometimes boolits seated below the neck don't shoot well, sometimes they shoot fine, it just depends.

Gear

[tomme boy]

PSI is the cutting agent. We used a broom to check for steam leaks at one of the factories I worked at. It would slice them bristles right off. This was around 300 psi steam.

[softpoint]

I cannot see a gascheck being "pulled" off as the boolit passes through the neck. The boolit is not being "pulled out the case, it is being pushed. There is pressure on the exposed shank of the bullet inside of the case at the moment of ignition, but there is far more pushing the base of the boolit . Even a very long boolit seated flush with the case mouth, with most of the boolit below the neck will still be pushed down the barrel, even with a very light powder charge.

[0verkill]

The only hazard I could imagine would be slip on checks that jarred off in transport or in the mag. Might get enough push to get out of the case but not be centered and stick in the barrel. Then the billion to one odds i would reallign it's self to form a perfect gas seal on the next shot. I still don't see it happening.

[wallenba]

I have always been under the impression that if a check that comes off, it comes off inside the case after seating, because it was not on tight enough, and fell on top of the powder. Or, came off in flight.
This topic came up with him after I asked if he could increase the leade in my K31 so I could have more cast boolit choices. Currently I use the Lee C309-155-2r. The double radius ogive seats out farther than a 1r.

[jhalcott]

Considering the fact that SOME of the checks came off the bases before going ten yards and hit the cardboard sheet a few inches from the bullet,I am sure they DO come off! Either in or JUST out of the bore. In .30 and .45 caliber guns too. I do not know the reason they come off, be it air pressure as they exit, like a drag parachute, or a drop in "PUSH" at exit. I do know they are moving very fast. I heard from a friend of my grand dad that HE found a check IN THE EMPTY CASE after a hunting trip. I never saw this nor heard of it happening to any one else.. I DID hear about and saw the gun that had a 30-06 FMJ jacket stick in the bore. The noses of surplus ammo had been ground off and reloaded into the cases. The next shot bulged the barrel very badly.

[GRid.1569]

... and if the check did come off.. there's still a lot of powder behind it, turning to gas to eject it from the bore...

it's only copper... still relatively soft and any "resistance is futile"....

[mold maker]

If The boolit leaves the barrel caused by the expanding gas, the check has the same vel because the gas is still behind it. Just how in heck could it come to a screeching halt while still having all that pressure behind it? Even if it turned side ways and allowed some gas to pass, it would have very little drag in the bore and would still exit with the pressure.

[milprileb]

Is this a debate of if there is a crash noise when a tree falls in the woods when no one is there to hear it?

[felix]

No, Ben, I have not ever had a check come off that I know of. Once a projectile begins to move, the expanding gas migrates to the center of the moving object, thus pressing on any gas check. This alone would significantly lower the probability of a check doing any twist-and-shout. ... felix

[Ben]

Felix,

A g/c coming off a g/c bullet and damaging a barrel may be possible, I'm no Physics expert ?

If someone has experienced a C/F rifle being damaged from a g/c that fell off the shank of a bullet and damaged a barrel, I simply am requesting them to step forward and tell their story, as I'd like to hear it.

Ben

[waksupi]

I'm with you guys, I think it is a non-problem, until proved otherwise. That's a lot of pressure coming out of the chamber, to leave a gas check floating around in there. I don't think it can happen, and is another old wives tale that needs put out to pasture.

[wallenba]

I'm with you guys, I think it is a non-problem, until proved otherwise. That's a lot of pressure coming out of the chamber, to leave a gas check floating around in there. I don't think it can happen, and is another old wives tale that needs put out to pasture.

My conclusion early on.

My impression of why a check separates after leaving the muzzle is this. The rim of the check is dragging in the bore, as it exits it acts like a drag chute and is pulled off. Imparted spin makes it depart trajectory. After sizing the boolit, and seating the check, often the check diameter is larger due to springback, and that may be the root cause.

[jhalcott]

I remember trying the check BELOW the neck in that old 30-30. The loads seated deep did NOT shoot as accurately as the check in the neck! BUT< I did NOT tweak those loads to see if accuracy could be improved to the point of the longer loads!?? Groups were only marginally larger in the short loads. Not even enough to eliminate them for hunting use. I assumed the longer run to the lands and possible increase in pressure caused the accuracy loss. I experienced the same accuracy problem in a short throated .308. I solved that with a bore rider mold of the same weight!

[bobthenailer]

IMO perhaps this could happen with the Lyman non crimping gas check but not with the crimped on Horndays.

[MBTcustom]

A week ago, I would have sworn that it was impossible for the gas check to come to rest anywhere but downrange, but in another thread, there is another feller that says that he found a gas check in a spent casing. He just posted it yesterday in another thread.
Caused me to do some quick soul searching. Assuming that you are using aluminum home-made checks, and assuming that you were depending on the powder or COW, or filler of some sort to keep the gas check on the neck, I guess that could explain this strange phenominon.
Personally, I always try to seat the boolit as deep in the throat as I can, and that practice has never allowed the gas check to go below the neck. However, one of the things that has been drilled into my head a couple of decades ago, was that the check needs to stay in the neck of the brass.
I suppose I don't know for sure. Its another one of those things that I thought was correct. Castboolits.com has shot all my other dearly held suppositions strait to the third circle of hades, so I would not be surprised if this is another one of those areas.

[David2011]

This may not be an apples to apples comparison because it involves straight walled cases but I'll toss it out anyway. My rattlesnake loads are 5 grains of Win 231 in a .45 Colt case. I seat a gas check over the powder cup up, fill the case with #9 shot and top it off with another gas check cup down, secured with a heavy roll crimp. I've had the gas checks go through test targets and even turn sideways and slice through snakes leaving a pretty nasty wound. Not a problem; death of the rattler was the intent anyway. Point being, the gas checks always leave the barrel and they aren't attached to boolits. FWIW.

David

[btroj]

I could see the old slip for Lyman's being deep seated causing a potential issue. If seated below case neck and handled roughly a check could fall into the powder. Not sure if it would end up in the barrel or not but it could happen.

With crimp in checks it should never happen. Make sure they are on tight and go shoot.

[.22-10-45]

Hello, everyone..interesting posts! Now as to that long-ago gas check stuck in brl. load..I was using a Lyman load..I'll have to check those old notes..but it was probably a fast shotgun type powder..I wonder if a low muzzle pressure from that fast burning powder in a 24" brl. would allow an uncrimped check to remain in bore?
Now if you guys think a stuck check is strange...How about this....I was shooting an unusually light 260 gr. cast-lead bullet in an Axtel 34" barreled .40-70 2 1/2" straight. I was using a never before tried powder..IMR4227. These were to be light target loads...so I had used 1.0 gr. Kapok filler..stretched out like cigar & gently inserted into case mouth..this was not compressed, but left loose. .030" fiber wad on bullet base. First shot went OK..saw bullet impact 100yds., 2nd.shot felt normal also..but as is my habit..I lkie to blow thru & have a peek inside just to make sure it's clear. Bore choked with smoke..blowing woudn't clear.
I felt obstruction right in front of chamber. Thinking I had a bullet stuck, & not wanting to push it thru 34" of barrel..I gently inserted rod from muzzle & pushed out. What came out of chamber looked for all the world like a shotshell overpowder wad. That kapok had been compressed into a quite firm .40 dia. disk 1/4" thick..fiber wad was on end.
Now can someone tell me how a kapok wad ended up at the breech end of a 34" long barrel AFTER the bullet cleared muzzle? (this 2nd. shot bullet impact was near 1st. one).
No damage was done to rifle..but I did not shoot any more of these loads.

[Bullshop]

This may or may not have much to do with the question or situation but I feel should be tossed in anyway.
I was loading for a Marlin 30/30 using the long parallel sided 200gn LFN/GC from LBT.
It had to be seated so deep that the gas check and about three drive bands were exposed inside the case. I was shooting a duplex load with a very slow burning main charge. On inspecting boolits recovered from the dirt berm I could clearly see indentations on the exposed area the shape and size of the powder kernals. I guess the load was building pressure slowly enough that the forward part of the compressed powder charge was pressing against the sides of the boolit before it was pushed from the case.
The thing is the load shot so blasted good I adopted it as a favorite. Maybe I was just lucky?