airspace

F

freire

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Fellows, i'm having a bit of a dilemma.
I recently received my Bertram brass, and today started to load them up mostly with the intention to fire form the brass.
70 grains of fg and 560 grains minie ball 575" diameter, after fire forming i intend on using a different bullet that comes out of the mould at 485 gr and 600" diameter.
I try to seat the minie ball at 2.450" but few seconds later the minie ball starts to slid out and some of them come out as far as 2.900".
I always hear the experienced people advising against leaving no airspace , tried to crimp to no avail my die is as far down as possible and the crimp that i get is not enough to stop the minie from sliding. is it safe to shoot with the airspace ?
Anybody ever had this issue? any way to fix this?
Thanks
Victor.
 
fill the cavity of the Minie with bullet lube and use some wads under it. if this is for the snider I would not use a .600" conical unless I knew my groove diameter at the breech was about that size round ball in pure lead is ok but most conicals are .585" to .595"
 
IIRC, I had a bit of an issue with a 577 ammunition. I was using a HB at 530 grains. But it would slide in too far was the issue. Smellie had helped me out with some advice about original loadings. At his suggestion, I put in a tube of cardboard, not corrugated...about .030 thou. It displaces volume in the voluminous case. It can be used as a step to rest the bullet on to hold it up til it's crimped as well.
Good luck though.
 
You clearly don't have enough neck tension. You need either a smaller sizing die or you need a smaller neck expander/flaring plug in the powder charge die.
 
BCRider said:
You clearly don't have enough neck tension. You need either a smaller sizing die or you need a smaller neck expander/flaring plug in the powder charge die.
Click to expand...

Thanks for your help guys, but the way i see it it's like i have a pocket of air trapped between powder and minie ,and BCRIDER is right about neck tension but there's nothing i can do with my dies to improve the neck tension, even if i buy another set of dies i might continue with the problem of neck tension unless it is a different manufacture , but i'm unaware of anybody else making this large set of dies.
Thanks
Victor
 
What brand dies are you using? I know Lee & RCBS make .577 Snider, but before he retired Jim Goodwin of NDFS used to make several sizes of .577 as well as .577-.450 MH due to chamber/bore spec differences.
Might be worth double-checking your case lengths to make sure they're getting deep enough in your seating-die to give decent neck-tension. If need be are you in a position to get a bit of the end of your seating-die turned off, if you need to crimp your cases more firmly?
 
My set of dies are made by lee and i have my seating die turned off , even like that not enough tension to hold that air pressure trapped in the case.
but i believe i fixed my problem, pulled the bullets out and used one square of two ply toilet paper to get rid of that air pocket, no more air pressure forcing the bullets out now.
Life is good again:rockOn:
Now coming back to my .600'' conical bullets, should i slug my bore at the breech?
 
As I say above, corn starch works well for filling the void. I use it to reduce loads and particularly when loading round balls in a .45 Colt (plinking load) which creates some of the same problems you describe (but I can easily adjust neck tension on the .45). Gives a wonderful addition to the muzzle blast too.
 
what's happening is you are creating an air piston with the air trapped in the hollow base of the minie.

I use 2 thin card wads(punched from something like a cereal box or a beer case) on top of the powder then a lubed felt wad(made from felt wool) and seat my bullet in my case for my cadet carbine I had I used a .600 round ball cast in pure lead in your case with the minie fill the hollow base with bullet lube(make sure its for black powder) and seat it
 
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