gas check below the neck: NEVER AGAIN!

[mike in co]

this is not news with me, but there are people that keep saying its no big deal.
i have been casting some 311413's out of pure lyno and trying them in a few 308's i own.
in 10-15mph winds i shot a 1.0x 5 shot group at one hundred yds from a used plama bbl'd 98 mauser in gi stock with bedding and a scope.
today i tried my 7.62x51 fn mauser. the original bbl was replaced with a commercial copy, so not as nice as the palma bbl, but the gun shoots well. the issue was that i wanted to go to 0.310 with the commercial bbl but that put the base of the boolit below the neck. i HATE gc's below the neck( i have watched such gas checks impinge on my chonograph, and shot gun like patterens on the target). well i said give it a try accepting boolit fit over gc location. BIG MISTAKE. THE ONLY CONSISTANCY WAS AT THE CHRONO, 4 OUT OF 5 , FIVE SHOT STRINGS WERE SHOT GUN PATERNS!
one string put 3 shots in less than an inch but with on shot THREE INCHES AWAY and the fifth shot only FIVE INCHES AWAY!

NEVER AGAIN WILL I ASSEMBLE A LOAD WITH THE GAS CHECK BELOW THE NECK!

i will try these again with the 0.309 dia boolit that puts the gc above the neck.......yes one thou diff makes a big diff in OAL.


mike in co

[Gun Junkie]

Mike,

Thanks for sharing your pain and reminding me not to let the gas check get below the neck. Not generally a problem with my Hornet, but with my K31...yup.

I had not thought about losing checks because of this tho. That's gotta be hard on the crony.

[Bret4207]

Sometimes you have problems, other times you don't. It didn't work out for Mike, for others it has worked out.

[jonk]

It's a crap shoot. Depends how hard the check is crimped onto the base. For Lyman older style slip on checks- nope, not going below the neck. For hornadys with a good crimp, generally not a problem for me.

Sometimes if it must be done I use a case filler to help ensure the check doesn't move. Superglue works well enough too.

[lead-1]

Can I jump in here being a new guy to cast shooting in a rifle? I went out and shot a few rounds of cast .30-06 the other day and the accuracy was lousy but it was my fault, I didn't lube the bullets. That being said I wondered to myself when I was loading those trial rounds,
What keeps the gas check from coming off the bullet when it is dragging back thru the neck, I know the force of the powder pushing it out but could the check come off the bullet and be left in the barrel? The reason I was curious to this was the fact that I knew the checks were inside the case and definately below the neck line. Do I simply not shoot anymore of these bullets knowing the depth of the bullet, they were seated at 3.245, any less and they would be too long OAL?
How much does this contribute to lousy groups being seated below the neck, an extra 1/4 inch or an extra 2 inches?

Sorry to tag into your post but I'm new and curious.

BTW, they were 185 grain lead spitzer type bullets with gas checks.

[mike in co]

hornady gc's, 314 sized down to 310 and 309....lots of clamping force.


just too inconsistant(again...) to ever try again......



mike in co

[Bret4207]

Annealed check have far less spring back and might have worked. But, to each their own. Some folks can't abide checks below the neck, I can't abide bases that aren't well filled.

[Larry Gibson]

Mike

That is why I always advise not to seat a GC below the case neck if at all possible. There are several things that can go wrong. They don't always go wrong as Bret says but as Jonk says; "it's a crap shoot". The only way I shoot cast with the GC below the case neck is with a BHN of 18+ and if the GC is securely crimped on (no old Lymans or homemade ones here) and I'm using a dacron filler. The dacron filler protects the base of the bullet (seems to anyways) and prevents riviting, crooked bases and GCs coming off inside the case. with some cartridges having short necks it is sometimes necessary so i always take the above precautions which seems to work for me so far.

Mike, does 311299 work in that rifle? I have both moulds and find the 314299 doesn't shoot well in tight bored and grooved .308s. It does in worn .308s but not in tighter ones. Always worth a try if 311299 isn't shooting up to par, especially if the 311299's nose is an easy slip fit in the muzzle.

Larry Gibson

[TAWILDCATT]

I shot the Lee 312-160 TL in my springfield unsized,and bullets were barely touching each other at 100yds.I use Ed Harris load of 13 grs red dot.my gun is WW1 barrel made in 1914 and receiver is under 500, my normal bullet is Lyman 311291.

[JeffinNZ]

I'm shooting Freechex alum. slip on checks below the neck in my .303 Brit and they shoot just dandy.

[Maven]

Never had a problem with this in any of my rifles with Hornady gas checks. However, I can understand why one would be loathe to try this with slip on GC's.

[Jim]

I muz' be dune sump'm wrong. I'm on my, lezzee, bout umpteenth box of .30 cal. checks and my eleventysecond box of 32 cal. checks and if they're comin' off, I sure as sundown can't see it.
Seriously, I have nothing to measure against other than my own experience. I started out putting checks on with a Lee push-thru nose first. I DID have some checks come off at one time when I switched to checking base first and went back to checking nose first and have never changed again.

[mike in co]

I muz' be dune sump'm wrong. I'm on my, lezzee, bout umpteenth box of .30 cal. checks and my eleventysecond box of 32 cal. checks and if they're comin' off, I sure as sundown can't see it.
Seriously, I have nothing to measure against other than my own experience. I started out putting checks on with a Lee push-thru nose first. I DID have some checks come off at one time when I switched to checking base first and went back to checking nose first and have never changed again.

do you have the base of the boolit below the case neck ?

do you shoot sub 2 moa at 100yds ? (current project was sub moa goal)

what kinda of velocities ?( current project was 2200-2400fps)

and lastly, if youes are staying on , good for you, but i had my 8mm masuer pepper my chrono with gas checks...taking pcs off the front screen base in little bits...with nice round marks.


mike

[Larry Gibson]

Mike

Likw we both said; sometimes they do and sometimes they don't. If they are seating the slip ons and they are not crimping on (my home made 8mm with the "bottle cap" top crimps on even though it is a slip on design) then my belief is the ones who've not have problems fall into the catagory of motorcyclists; "there are motorcyclists who have had an accident and there are motorcyclists who will have an accident. I went a long time before I had one and only had one occasionally after that. However "occasional" was to often for me. Never had anything "bad" happen other than piss poor accuracy and a few chips out of the chronograph screens but still it's not something I like to have happen. I still have numerous Lyman slip ons of verious calibers and use them only when the GC is not seated below the case neck. The Lymans and others work just fine then.

Larry Gibson

[jonk]

Of course the question isn't, is the check coming off; the question is, where? If it flies off at the muzzle, no problem. If it is comgin off in the case, then we have trouble. Accuracy, leading, etc.

[Bret4207]

I don;t want the GC coming off at all. I only have a couple boolits that extend past the neck but so far (!!!!) I haven't had a problem. OTH, I have had Lyman checks come off and mark the target even though they were well up into the neck.

Sometimes ya just can't win...

[303Guy]

Are you sure you putting them on the right way round?[smilie=1:

http://i388.photobucket.com/albums/oo327/303Guy/MVC-360F_edited.jpg

:mrgreen:

I have a pic of a fired one somewhere. They don't come off. I solder the part facing the bullet which goes into the mould. It was just a trial and I never range tested it. Too much trouble and no point, really.

[GLynn41]

I have lots of folk tell me that a gc below the neck does not matter-- but when I started it was a no no -- now I have 2 necked down revolvers and I seat them out and put a drop of super glue on the GB gator checks I have-- so I have not had a problem