Acceptable Level of Leading from Barrel Weight change?

[Daryl]

I've been casting about 7-8 years now and shooting thousands per year. I made the mistake of starting with 9MM and did not have much luck. But, now, I'm very, very happy with my other casting. Everything under 900 FPS I'm virtually lead-free in the barrel even after many rounds. I do try to condition my barrels regularly with Bore Brite and Tetra oil. I use lead almost exclusively in 32 SWL, 32 HR Mag, 38 SP, 44 Mag (under 900 FPS), 45 ACP on a regular basis.

So, I dusted off a pile of 9MM the other day and gave them a try. Here's the details:

Magma mold 122 - Flat Nose - Bevel base. One lube groove that I lube with Magma's lube. I had a .357 star sizer so I used that. The BHN is 15. Loaded on a Dillon Square Deal and taper crimp die set to SAMMI specs on case mouth OD. I used 4.5 grains (max load) CSB-1 (similar to Universal) and COL is 1.05. This same load with Berry 124FP generates 1,100 FPS in Glock 34 - so I figure the velocity on the lead boolit may be that plus 25-50.

I used a new Taurus PT111 Pro G2. Conditioned the barrel as above.

Put 100 rounds through it and all worked very nicely. No degradation of accuracy throughout the trial.

So, here's my question. I weighed the barrel before cleaning. Thoroughly cleaned all lead out with the chore boy method. When all was said and done, the clean barrel was 2 grains lighter. So, that's my guess - there was 2 grains of lead and some powder/lube debris on the barrel. This is the first time I tried weighing the barrel before and after. Has anyone else done such measurements and, if so, what amount did you find to be "heavy leading" that affected accuracy?

One point to note, this load shot more consistently and a better group than the Berry 124 FP.

Thanks

[Blackwater]

Well, you ask a somewhat interesting question, but I can't help wondering why it really matters. I've long had minimal streaks here and there in various loads, but they seem to "shoot out" with each successive shot, and has never affected accuracy or performance, so I've always just shrugged, and enjoyed the loads anyway. After all, we're not engaged in cleanup in hospital rooms where everything is supposed to be sterile after we're done, just clean enough to work right, and reliably. I'd also have to ask if you're sure beyond doubt that your weights are accurate. If it was on an electronic scale, at the weight level of a barrel, I'd have to wonder if it weren't a wandering zero on the scale, a thing not unknown in electronic scales. Sorry to be so agnostic, but most of us boolit shooters are, by necessity or by choice, really more "practical" loaders and shooters than we are absolutely scientific, and it seems to work, but I DO applaud your taking real and actual factors and asking intelligent questions. Good on ya' for that.

[runfiverun]

we had a thing going on here some time back about everybody weighing their barrels.
it pretty much ended when someone asked if they lost accuracy.
they all said NO, and someone else asked why they were wasting their time.