smokeless powder +cast bullet +lube cookie = pressure issue?

[swmn]

Just curious, haven't tried it. What I have been doing is fooling with black powder in .45 Colt.

Using just smokeless powders, I am accustomed to seeing more and more lead as bullet weight, hardness and velocity increase. I have spent a bunch of time and money gunsmithing that Redhawk of mine and I was down to a tiny amount of tolerable leading after many rounds with good accuracy. I felt like I had the Redhawk dialed in and was fooling with BP for the fun of it.

Loading BP with a lube cookie between the powder charge and bullet base, now I know what "no leading" looks like. My gun has never before been this clean.

So I am wondering about putting a lube cookie in between the bullet base and a charge of smokeless.

FWIW I am using 45-45-10% (by weight) beeswax- crisco- olive oil. Melted together in a double boiler, and then poured out liquid onto a layer of tin foil to cool, my lube cookies run a reasonably consistent .010" to .015" thick, I punch them out with a empty cartridge case so I have a push fit against the case wall.

 

[rbuck351]

There is a lot of info missing but if you have a good load without the lube cookie, drop your powder charge just a bit and try it with the lube cookie. I don't know what size your bullets, barrel, throats and groove are or bullet weight and powder type and charge so I can't say much about why it's leading but a full tilt 454Casull can be shot without leading without a lube cookie if everything is right. Your lube sounds like it may be better for BP than smokeless but as a lube cookie it should work anyway. But, as always, when you change anything with a load, you should back down and work up with the new components. Also, I would put wax paper or something between the cookie and the smokeless as that sounds like it is a soft lube that may soak into the powder. Doesn't sound dangerous though so why not.

 

[swmn]

Thanks for the review Rbuck, that was pretty much as far as I got, though the idea of a wax paper undercookie hadn't occurred to me.

One typo above, my cookies run 0.100 to 0.150, right around 1/8th inch thick, not 10-15 thousandths.

The internal dimensions on my Redhawk are known to be sub-optimal, but I got them to good enough, as documented in a lengthy thread elsewhere on this site.

I am going to start with my steel target load, 7.5ish grains of universal under a 230gr cast bullet. It only clocks 750-800fps, around 12,000 cup and the Redhawk rated to possibly 32,000psi. I figger I'll start with that one, just add the cookie without changing the charge, see if velocity goes up and see if leading goes down.

Thanks for looking everybody, my hypothesis for smokeless is the lube cookie reduces the volume inside the case- even as a melted liquid- so starting "somewhere" the smokeless charge will have to be reduced to compensate.

 

[Paul H]

I like to keep things simple so would suggest adjusting whatever dimensions are out of wack to make the gun cast friendly w/o needling lube cookies. I've shot 100's of pounds of cast bullets out of revolvers. So long as the bullet is the proper dia, proper alloy (hardness), a good lube is used and no dimensional problems with the gun; you'll get no significant leading and excellent accuracy with smokeless powder.

Possible gotchas with lube cookies are the lube can melt and mess up the powder, if the lube/powder does not fill the case 100% the lube cookie can end up in a different position in each round and produce inconsistent shot to shot ignition and it's an add step to perform or possibly forget. As I recall the primary benefit of the lube cookie for BP loads is to keep the fouling soft and thus easier to remove.

 

[Alangaq]

If you are under 800 fps like you say, then forget the lube cookie (its only going to make everything a sticky nasty mess eventually) and go with a softer alloy and perhaps bigger dia bullet, to avoid the leading. Likely your alloy is too hard for such minimal pressure loads and your bullets may not fully obturate and seal the bore..

 

[Alangaq]

Forgot... if your normal load leaves a bit of lube on the muzzle then you know it is doing its job and making it all the way down the barrel with the bullet. No need to go overboard with a lube cookie for smokeless powder.

 

[Bullelkklr]

that sure seems like a lot of extra work. I push some pretty hot 330 grain pretty hard bullets out of my redhawk and I don't do much scrubbin on her when I am done. (up to 1150fps or so)