first time powder coat = major leading in last inch of barrel

[Love Life]

How's the throat?

[popper]

According to Hodgdon, you are almost a grain over MAX load for jacketed. I'd guess your alloy is too soft. It's not a 10mm.

[reddog81]

I've heard that leading at the muzzle end is indicative of too little lube or in this case maybe the powder coating isn't strong enough.
i'm not close to a manual but your charge appears to be in the 10mm range or at least the max of 40. Try a lighter charge or do another coat of powder coat and see what happens.

[Motor]

According to Hodgdon, you are almost a grain over MAX load for jacketed. I'd guess your alloy is too soft. It's not a 10mm.

This is not something I looked at and does make a lot of sense. Just like undersized boolits too high pressure will have similar results.

Motor

[mistermog]

according to quickload im at about 1025 fps. didnt have a chrono though. wonder if ql is wrong fir 40? ive checked my 9mm load and it was within 5fps or so.

i hadnt thought of this aspect before, i guess it is possible.

edit: wow you guys are right... this is weird! (below quoted from 2 random web pages, so that makes it true)

The hornady 2009 manual list .40 data using a Hornady 180gr. XTP bullet, WIN SP primer, 4” barrel, C.O.L. 1.125”

Start load 4.1gr. = 797 f.p.s. @ 23,800 P.S.I.
MAX load 5.0gr. = 947 f.p.s. @ 32,900 P.S.I.

according to QL I am at 32,200 psi, but my barrel is .25 longer than that and im using .9 grains more.

I didnt see anything weird pressure signs on the brass or anything?

[Motor]

"I didnt see anything weird pressure signs on the brass or anything?"

Not surprised because you are very likely NOT over pressure for the cartridge. Cast lead even hard cast lead produces less pressure than a jacketed bullet.

HOWEVER: You are very likely over the pressure threshold for your cast boolit.

Meaning your load is too hot for your alloy not for the gun.

Motor

[mistermog]

Ahhh.. true, I wasnt thinking about that. I hear pressure and I immediately go looking for charge weights and etc making sure i dont risk doing something stupid.

Is there any correlation to 9mm? I shoot the exact same lead (same pot actually) in 9mm at the same speed, give or take 10 fps.

[Motor]

It's hard to say. 2 different calibers and 2 different guns and definitely 2 different boolits so there really is no point to compare them.

It's easy to tell. Just back your 40 load off to cast bullet data specs or at least jacketed starting loads and try again.

Motor

[mistermog]

yep, makes sense, i dont tend to try to get toward max loads but this was my powder coating test round hehe

[guncheese]

even with proper fit and well cured coating
i had leading in my 3rd gen smith
until......
i polished the bore so it looked less like a gravel road
it had been leading no matter what i put thru it
once it got shiny
all was better

[jcren]

For what it is worth, pressure being a function of psi, the smaller (9mm) bullet is actually seeing significantly less pressure on the bullet base at any given psi rating.

[mistermog]

ill admit ive had more trouble out of my M&P barrels than any others

[Maximumbob54]

I skimmed this thread and didn't see anyone mention crimp. I assume the taper crimp applied isn't breaking the coating so it fails in the bore. And has this load had the plunk test in the chamber for fit? If the slide is force fitting the bullet in the bore's leading edge then that could also break the coating.

[Smoke4320]

I taper crimp my AR calibers .. 300 blackout, 458 socom
and recovered bullets do not show any signs of coating failing
as a matter of fact I get better groups crimping my blackout bullets and no leading

[popper]

less pressure on the bullet base

less force, not pressure. It's still a hot load and will beat the gun to death even if it doesn't burn all the powder. You only gained 50 fps over a max jacketed load

[mistermog]

Yes they are taper crimped. Havent tried the plunk test to be honest, does chamber easily though. No rub or anything popping out manually.

[OS OK]

http://castboolits.gunloads.com/arch.../t-266639.html

Change to a quality powder coating…that looks like Harbor Freight stuff??? Get a Hi Gloss Clear, try that before you start playing the color game…just a thought, but with a greased lead boolit if you get leading at the last inch of your barrel, you ran out of lube…PC'ng is lube replacement right? Bad PC = Bad lubing…and find some air soft BB's they make all the difference in PC coverage...

Hope you try it…charlie

[Motor]

If a powder coated boolit can withstand the "cube" test I can't see any amount of crimp hurting it.

Except if it's causing it to be too small for the bore.

Motor

[bangerjim]

Too much of ANY kind of a crimp will scrape the PC off as the boolit leaves the case. PC will withstand the hammer test, but can be easily scraped off by a sharp case mouth....or a sizing die if the boolits goes thru catty-whompus! I have seen it happen. And my testing shows PC scraping by over-crimping when I was breaking down loaded rounds for testing early on during PC development.

Just use common sense crimping, no matter what style you choose to use.

bangerjim

[fredj338]

If a powder coated boolit can withstand the "cube" test I can't see any amount of crimp hurting it.

Except if it's causing it to be too small for the bore.

Motor

To add to Jim, also over crimping often resizes the bullet, particularly at the bearing surface, so that can cause all kinds of accuracy & leading issues.