Lube, alloy, groove(s) & Obturate Leading

[motorcycle_dan]

This according to the Lyman site:
http://www.lymanproducts.com/lymanproducts/index.htm

They say leading occuring at the breech end (what happens in my XD .45ACP pistol) is caused by gas leaking around the base of the bullet causing leading.

I looked up Obturate and found it was Swelling for lack of a better term.

Which makes me contemplate several things.

1. Lube grooves - I'm currently shooting a 228gr Lee RN bullet. It seems to be working pretty well but I do get some slight leading at the breech end of the barrel. I'm thinking of going to a single lube groove bullet design. Either the H&G #34 or the Lee 200gr RNFP. What are the advantages of single vs. double lube grooves? Would a deeper single groove allow the gas to "obturate" the bullet base better than the shallower twin groove?

2. As mentioned several times here, recovered bullets usually have the lube still in the groove. Will multiple lube grooves that are shallower provide more lube or less?

3. What exactly does the lube do? Does it lube the bullet it is on as it travels down the bore? Or does it lube the barrel so that the "NEXT" bullet gets a pre lubed bore in which to slide on. I've asked this question of several seasoned casters and never got an answer that made sense.

Appreciate any insight people could lend. All of my casting is for pistol. My lead is made up of wheel weights 90% and linotype 10%. I cast them frosty from a Lee 6 Cavity 225gr RN. Size them with a star sizer and some kind of brownish lube sticks that came with the used equipment I bought.

As for rifle bullets, I have not convinced myself that rifle bullets are worthy of my casting. Besides, I can shoot just about as far as I can see with a .45
Dan

[StarMetal]

Colt Pythons had tapered bores. I can't see gas leaking by the base of the bullet in that case. The Colts still got some leading at the muzzle end with certain loads. I believe leading near the muzzle is the bullet running out of lube. The bullet speed is higher at the muzzle end also.

Joe

[Heavy]

Your alloy is to hard. Try 50/50 ww and straight lead.

[454PB]

I use harder alloys than you are using with no leading and good accuracy. The only question that jumps out is what size are your boolits? Have you slugged the barrel? I have found that some semi-autos have shallow rifling and an under size boolit will lead badly. Be sure you are sizing bore diameter and preferably .001" over bore diameter.

[Bass Ackward]

What exactly does the lube do? Does it lube the bullet it is on as it travels down the bore? Or does it lube the barrel so that the "NEXT" bullet gets a pre lubed bore in which to slide on. I've asked this question of several seasoned casters and never got an answer that made sense.


Dan,

There is a lot of debate about lube. And the mere fact that so many people use different lubes tells you that there is no easy solution. In handguns: 95% of the time lube is blamed, there is another problem. Diameter is too small or the barrel has a dimensional problem that breaks the seal blowing off the lube, or the mix isn't hard enough to handle pressure or short rifling. (short bullets require smoother more uniform barrels to amintain seal.)

Bullet design plays a big part in lube choice. The farther up the bullet you can place lube, the less lube you actually will need. And while (1) some people believe in a blackbore condition for shooting cast, (lube builds up in the bore so each bullet benifits from that point on) (RNFP designs), I prefer (2) a tight bullet fit and design that takes out what is left in the bore so each bullet must carry what it needs. (Keith/SW designs)

Guy number one may encounter problems in cold weather as remaining lube hardens if shooting rate is slow, and guy number two might lead in hot weather if his lube isn't sufficient to do the job. So that covers a lot of ground and once you understand it all, you will know more than what I do.

[Bucks Owin]

I use harder alloys than you are using with no leading and good accuracy. The only question that jumps out is what size are your boolits? Have you slugged the barrel? I have found that some semi-autos have shallow rifling and an under size boolit will lead badly. Be sure you are sizing bore diameter and preferably .001" over bore diameter.

Yep, same here. Namely, 50/50 WW and lino and fired unsized (.432") or sized to about .4305" fired in a .4295" barrel.....

The leading problems I found were because of using LLA. Lars Carnuba Red fixed that!

FWIW,

Dennis

[D.Mack]

Dan Think of lube as a liquid "O" ring, it can fill in minor imperfections in the barrel, slick up the barrel for this shot, and leave a thjn film for the next shot. Also if you find it on a recovered bullet, it probably means you are usuing too much, as any left on the bullet will cause it to be out of balance, effecting accuracy.
Leading at the breech is usually gas cutting, but there are several causes of this. some of these can be too small a bullet, too hard a bullet, if it is slightly small, or too hard a lube. If the lube doesn't liquify, it can't do it's job properly. So meaure your bore, size to groove diameter or slightly over, (or don"t size at all), and use a lube that liquifies at the pressure you are shooting.
So now the questions, what size is your groove diameter, what size are you sizing to, and what is that brown goop you are using.
Also, your mix is much harder than it needs to be, so save the lino for higher pressure loads. Now I'll start a contraversy. My personal rule is the brinell hardness X 100 - to 140 to find the velocity range for pistols---- so for a 900 fps load a brinell of 9 down to slightly over 6 will work fine. so if ww's are 12 they are a little hard for low pressure pistol loads, and adding lino isnt neccesary.
I hope this makes sense, as I just reread it, and am not sure I clarified anything. DM

[David R]

Lube is too thick. As 44 man sez, sticky lube is better in a handgun. If the lube is still on the boolit, then it is not in the barrel. Ditch your first unknown, the lube that came with the star. Get some 50/50 from LAR45, or some place else. You could also mix up some Felix lube. You could try to lube some of your already lubed boolits with LLA and see if the lead stops. SOFTER LUBE is MY opinion.

David