I finally got a chrono and was able to check my load I've been using. I'm loading a 230 grain cast lead RN bullet on top of 4.6 grains of titegroup, and shooting it from a 5" bbl 1911.

High velocity is 852 fps, lowest was 773, with avg of 814. It's a large spread, but I went through several systems of measuring the powder. For the hell of it I chrono'd factory rounds, and got a high of 834, low of 793, and avg of 820.

I am getting horrible leading my barrel though.

Am I on the right track?  Is there still some wiggle room to increase the velocity some?

Bill

Yeah, they are the bullets we traded. I had used the same load before with different cast LRN bullets, but like you said, it could be any number of factors that are different with the bullets.

So, if I'm understanding you correctly, the bullets could be slightly undersized (compared to the last ones I used), which means they don't completely seal off during combustion, which allows them to deposit lead on the barrel?

I've been using Titegroup for quite a while, which I understand is pretty slow-burning. A powder with a faster burn rate would help?  Can someone explain the reason for that?  I'm trying to understand the why's & how's 

Bill

Bill,
The theory as I understand it is that faster burning powders would tend to build up pressure behind the bullet more quickly, pushing the edges of the bullet base up into the bore and kind of sealing up the back end.  Slower powders would build pressure more slowly, which ought to allow more gas to leak around the unsealed base before/if pressure reaches a point where it can deform the base of the bullet, or obturate it, so that it seals up.  Faster powders and softer bullets would be better for that, as would a flat base be better than a bevel base, and a slightly oversized bullet would be better than a slightly undersize bullet.

You could try loading a few up with a faster pistol powder, if you have it.  If there's a silver lining with leading with 45ACP, it's that the rifling is much shallower than with 9mm or 40, so it's easier to scub out leading with 45 than with other chamberings.

I use W231. I use about 5.0 under a 175gr LSWC from http://www.bulletworks.com. It's pretty smoky, but it's an accurate load.

Bill, a little reading on bullet obturation- http://www.laser-cast.com/files/Understanding_bullet_obturation.pdf  and http://en.wikipedia.org/wiki/Obturate

As for your issue specifically?  We need to look at size issues very closely, both barrel and slug diameters.  What are they?

EDIT:  as for burn rates, maybe this will help-

Fast powder? That's like a major league pitcher delivering a fast ball.  Ball goes from zero to near 100 in a split second.  Slow powder?  That's like waiting for your car to go from 0-100.   In both cases the projectile hit the same speed.

Another example:  Fast powder? It's like being punched hard. Whereas a slow powder is like being shoved very hard.  Either way, you go down.  But the physics behind the matter are much different when you crunch the numbers.

I shoved a bullet through my barrel today (instead of relying on the recovered bullet), and it measured .4505" at its high points, and .4425" at it's low points. There was one spot that measured .4510" - don't know if that was just a little deformed spot.

Again, the cast bullets are measuring .4520"

Bill

Well crap!  I've got about 1000 of them. Other than changing bullets, is there anything I can do to minimize the leading?  Ultimately it's not going to hurt my gun, right? (other than forcing me to spend more time cleaning.

Bill

Thanks for the link Norse. I'm hoping that once I get to casting my own I can get them dialed in to where it's not as much of a problem - until then I'm stuck with what I can get. I've had some lead bullets that were no trouble at all, so I know it can be done.

Bill