Micro BPCR...

[Old Ironsights]

Anybody got a plausible data-driven reason why I can't use 4F in a .357 under a 358156?

Could 15gr of 4F generate more than 40,000 psi?

[montana_charlie]

It may not do anything you would find useful, but I doubt you would damage a firearm strong enough to handle the .357 Mag.
CM

[Old Ironsights]

Well, if it will shoot to even a partially reasonable velocity (800-1000fps) it would be useful.

My main concern was 4F vs 3F.

[rhbrink]

Try it and let us know how it shoots!

[Old Ironsights]

Planning on it. I'm doing a bunch of testing mid june. Just wanted to make sure it would do nothing more than be messy after shooting... ;)

[NickSS]

I have loaded FFFG in a 357 mag case using a Lee 158 gr RNF bullet. I did not weigh the charge but just adjusted my powder measure to fill the case to within an eighth of an inch of the mouth and crunched the bullet in. Worked well and shot surprisingly well in my 92 clone carbine. I was getting around 2 to 3 inch 50 yard 10 shot groups with it. FFFFG will probably give higher velocity but will not generate anything like Magnum pressures.

[August]

It'll be fine. Generally, you can expect more fouling with finer grained powder. FILL that case!!!

[Old Ironsights]

I have loaded FFFG in a 357 mag case using a Lee 158 gr RNF bullet. I did not weigh the charge but just adjusted my powder measure to fill the case to within an eighth of an inch of the mouth and crunched the bullet in. Worked well and shot surprisingly well in my 92 clone carbine. I was getting around 2 to 3 inch 50 yard 10 shot groups with it. FFFFG will probably give higher velocity but will not generate anything like Magnum pressures.

That's what I was hoping. I have LOTS of 4F... way more than I'll likely ever use for pan prime (I think I have 1/4 # of 7F too...) so I was thinking that a pile of 4F .358156s could be a smoky hoot...

But for about forever all I've ever heard is "never never never ever never use 4F for anything but Prime..." but never got a clear answer why (other than it tends to pour out of the vent-hole in my Firestorm Flinter)

[lreed]

Hello, I have a Lyman Black Powder Handbook that gives a 4f load of 15gr with a 150gr bullet # 37583 and 27.5gr 4f with a rb in their Lyman Navy colt repo. Hope this helps.
lreed

[Old Ironsights]

Thanks!

[Old Ironsights]

Well, I now have 50 "38-20s" loaded up.

With a checkless 358156, and a 1.3cc Lee Dipper throwing 20gr +/- in 3F & 4F, I get a slightly compressed load.

Chrony testing mid june...

[Old Ironsights]

Interesting results.

4F = 1100fps (av) from the Rossi
3F = 1000fps (av)

The 4F was less smokey too. Fouling from 40 loads (30 4F, 10 3F) was considerable, but contained completely in the barrel. Scrubbed right out with a bronze brush & some water & Alcohol. The action was not soot impinged at all.

[Pepe Ray]

Could the fouling be reduced by using BP lube in your sizer/luber?
Also, I wondered about the need for sealed primers. For instance, will ordinary vibration cause 4f to migrate thru the flash hole? and does it matter?
Pepe Ray

[Old Ironsights]

Could the fouling be reduced by using BP lube in your sizer/luber?
Undoubtedly. The bullets were lubed with LLA. If I were doing it "for real" I'd pan lube with SPG or homebrew.


Also, I wondered about the need for sealed primers. For instance, will ordinary vibration cause 4f to migrate thru the flash hole? and does it matter?
Pepe Ray
Dunno, but don't see it being an issue. The loads were at least 5% compresed, maybe more, and stored/transported nose down.