Tried some PB boolits---

[Goatwhiskers]

---and it was less than satisfactory. Been playing with some RD359190GC and had gotten phenominal accuracy in my Cadet Max. using A1680 powder. Tried the same boolit today, PB version, with the same loads and I just as well having been shooting buckshot. I will say that velocity was running from middle 1900's on the low end to about 2145 on the high end of the loads. Leaded the heck out of my barrel too. Should I just back off to say 4227 or 2400 and go for lesser velocity with the PB boolits? Speed is not my objective anyway, accuracy is, just thought not having to buy GC might be worthwhile. Got to go start cleaning a barrel now. Goatwhiskers

[SlowSmokeN]

It sounds more like a boolit size issue. From what I understand you need to slug your barrel and make sure your boolit is .001 bigger. If it is to small you will get blow by around the base of the boolit leaving lead all the way down the barrel.

[Wayne Smith]

Yeah, we need loads more information to diagnose your issues. Speed alone isn't it. Fit is king, knowing relative sizes is critical. Alloy is second, yield strength of the alloy will tell you the likelihood of boolit stripping as it hits the rifling at those speeds. This allows blowby and leading and destroys accuracy, too.

[Goatwhiskers]

Another angle for me to consider. My bore is .358 and I'm sizing to .359. This worked fine for the GC boolits, maybe I should look at shooting the PB as cast which normally seems to run 360-.361. This is straight WW material, which with the GC version gave me a 9/16 by 1/4" group at just over 2000fps. With a little help we'll figure this out. Goat

[Goatwhiskers]

A dab of further info, am using LLA dip lubed. I noticed that when I hit the barrel with bronze wool the leading was only in the last 6" or so at the muzzle, after that the bore was slick as greased guano. The leading scrubbed out easily enough but I have the bore soaking in Kroil and will scrub again tomorrow. It is as tho the lube just gave out before exit. I'm gonna try other powders shooting for lesser velocity, also plan to cast some more and set another round with as cast boolits to work out the possibilities one at a time. Great excuse to shoot some more. Goat

[HangFireW8]

That definitely sounds like you ran out of lube before you ran out of barrel. At 2000 fps, lube is not just a lubricant, it is a coolant and sealant. Without a gas check, your lube has more work to do. In a rifle barrel, it has all that work to do for a longer time than a short barrel.

While we all know that LLA can do rifle, PB can be done at rifle velocities, etc., but that doesn't mean it's all easy to do. When pushing the limits, it is best to test one variable at a time and find the limit where it falls apart (if ever). I would suggest falling back to a known, quality lube, designed for rifle, that fills the grooves, and fill all the grooves. If that works OK you can back off one groove at a time until you start to get leading. The most accurate way to use lube is to use the minimum required, but it can be easier to start with too much and back off until you run into trouble, then start off with leading and find your way forward.

HF

[runfiverun]

you just learned why gas checks were invented.
back the p/b down to 1200 and go from there.

[stubshaft]

Speed is definitely one of the issues! As is the alloy you are trying to drive that fast.