Cast Bullet Seating Depth

[lgm270]

I read a piece on  casting rifle bullets that said you should NEVER seat the base of the cast bullet below the case neck.  He didn't say why, but that it shouldn't be done. 

I was contemplating a custom 240 grain .308" bullet mold for use in a 30-06.  I think this bullet would have to be seated below the case neck. 

Does anyone have any comments on this? 

[stimpylu32]

With out knowing for sure why he said that , my best guess would be that he was worried about the hot gas melting the bullet above the base and not allowing for a proper seal as the bullet went down the bore .

stimpy

[bilmac]

I wonder if there is a danger of gas checks coming off. I have kind of made this a rule for myself. That is why I would much prefer to load cast bullets in a 30-30 and not in a 300 Savage.

[jhalcott]

  I seriously doubt the lead would be melted in the short time it is exposed to the heat. The check MAY come off and/or the bullet may be damaged by the PRESSURE of the expanding gasses. Possible contamination of the powder also exists with the base well below the case shoulder. That might cause erratic ignition and velocities and accuracy! I HAVE seated certain bullets deeply into short necked cases. This was USUALLY done at the range when I fired them VERY soon after loading. I have also PULLED cast bullets from cases that didn't fire or were considered to hot to shoot. SOME TIMES the checks stayed on the bullet ,other times they stayed in the case. Did I mention that I only use Hornady checks? I receive a bag of several hundred 38 special rounds loaded with all manner of components. They had been in a flood for a week or so. When I pulled the bullets, some of the checks stayed on the bullets and some did NOT, so it CAN happen on straight wall cases too!

[blhof]

Probably the main reason to not seat too deep is to prevent lube contamination of your powder from lube above the base or gas check.  I've got a few hundred 38 and 357's loaded with Lee tumble lube from years ago.  They worked fine when I first loaded them, but after a while, I started getting squibs.  I pulled some and found some of the powder in a lump.  This was my early loading with a turret press and casting.  Now I wipe the base off on all my bullets before seating and don't seat below the neck on tapered cases.  I've had no further problems and I've loaded large lots of 9mm and 30 cal cast and they've sat for a year or more without a single misfire or squib.  I did check the powder charges every 3 rounds after checking the 1st ten on my original 38/357 run, so I know the powder load was correct.

[Sweetwater]

Probably the single reason I haven't had this problem, is that I use a powder that fills the case; therefore the gascheck is virtually held in place by the powder. I keep the bullet bases clean and those long bullets just go like they are supposed to. ie 356W with 250gr FPGC - without a hitch.

Regards,
Sweetwater

[res45]

For cases with short necks like the 300 savage you can use poly fill to protect the base of the bullet,Lyman make the three different cast bullet molds that will work in the 300 savage case two require seating the bullet below the neck and into the firebox.  Evidently it doesn't hurt accuracy to much,I know a guy that shoots cast in a Savage 99 like mine that can hold a 2" group average at 100 yards.  

Thats my next cast bullet project after I get my Mosin cast load worked out and in the books.  The mold he uses is the Lyman 311291 I believe,some of the older Lyman manuals list the mold and the caliber there best suited for in a different format that there newer manuals and I don't have access to my old ones at the moment to check.  

[calvon]

Some good advice above. If I were using gas checked bullets I'd not seat the gas check deeper than the base of the neck. That would keep it from falling off prior to shooting. If I were shooting bullets without a gas check I would seat so the bottom lube groove was still within the neck. This would prevent the lube from contaminating the powder prior to shooting.

It's my gut hunch that should the base of the bullet protrude beyond the neck into the "powder room" there would be no "buttoning" of the base at the moment of firing because of pressure. The pressure on the exposed sides of the bullet would be equal to the pressure on the base. Thus the bullet shape wouldn't change because of pressure.

[Lloyd Smale]

the correct answer.

Probably the main reason to not seat too deep is to prevent lube contamination of your powder from lube above the base or gas check.  I've got a few hundred 38 and 357's loaded with Lee tumble lube from years ago.  They worked fine when I first loaded them, but after a while, I started getting squibs.  I pulled some and found some of the powder in a lump.  This was my early loading with a turret press and casting.  Now I wipe the base off on all my bullets before seating and don't seat below the neck on tapered cases.  I've had no further problems and I've loaded large lots of 9mm and 30 cal cast and they've sat for a year or more without a single misfire or squib.  I did check the powder charges every 3 rounds after checking the 1st ten on my original 38/357 run, so I know the powder load was correct.