F.P.S. 40cal.PRB

[sjf]

Whats the max.(safe) F.P.S. for a 40 cal. PBR.I was figuring on using from 40 to 70 grs. fffg .

 

[Trench]

What manufacture of barrel do you have? Do they list a safe max load?

 

[sjf]

Its a 38 inch 40 cal.GreenMountain barrel with no information with respect to the 40 cal..only info they give is for 32 cal then jumps to 50 cal.

 

[roundball]

Its a 38 inch 40 cal.GreenMountain barrel with no information with respect to the 40 cal..only info they give is for 32 cal then jumps to 50 cal.

That is an incredibly strong barrel given its 15/16" size and small .40cal size bore, its walls are very very thick. And GM uses that same size 15/16" barrel for the larger bore sizes of .45/.50/.54cals.

I have a .40cal GM 15/16" x 33"(w/Breechplug) Flint barrel and use the following:
HUNTING:(small game)
40grns Goex 3F
.018" pillow ticking
Hornady .395/92grn balls
TARGETS:
30grns Goex 3F
.015" Oxyoke Oiled Patches
.395" cast lead balls (Eddie May/Georgia)

My 33" is heavy and your 39"(w/Breechplug) is going to be very heavy...better start eating your wheaties :grin: and you'll really like the outstanding accuracy.

You can easily run the powder charges right on up due to the barrels strength and light weight ball...I chronographed mine this summer as follows:
05/24/08
GM .40cal 15/16” x 33” Flint barrel
1:48” round ball twist
.015" Oxyoke Oiled Patches
.395" cast lead balls (Eddie May/Georgia)
Wiped the bore after every shot
Pact Pro MK5 Chronograph at 15 feet
Goex 3F powder charges
Average velocity rounded off to nearest 5 fps

30grns = 1300 fps
40grns = 1400 fps
50grns = 1525 fps
60grns = 1620 fps
70grns = 1760 fps
80grns = 1940 fps
90grns = 1950 fps
PLUS:
.40cal 15grn solid rubber practice ball
50grns Goex 3F / velocity = 1675 fps

 

[buckhorn]

In the old Mountain State catalog, GM had a chart for different calibers.

For .40 patching .15-.018.,
40-60 grains 3f
.395 ball for hunting and .400 ball for target.

 

[Tom Compton]

Two of my .40s have 7/8" across the flats Douglas barrels 42" long. Flinter ran 10 shots over the screens at avg 2120 fps w/ SD of 9. This was .395 PRB, .017 cut patch and 75 gr Goex FFg. The difference in my MV and Roundball's is explained by the extra 9" of barrel length.
TC

 

[sjf]

The barrel is 15/16 ,Roundball, and thanks for all the data ,it well give me a good starting point.Im not going to expect to much until the barrels broken in (50 to 100 rounds?).

Thanks Stoat Im going to try and find some .400 RB's ,sounds like it might be the way to go to get the best accuracy throgh this barrel(keep everything tight and in the rifling).

 

[sjf]

Im going to start at 30grs. and crono my progress thats why I was wondering about the safe F.P.S..By what Roundball was saying I can go down to 30 grs.,and I know because of barrel length Ill get a higher f.p.s. reading .Thanks for the heads up anyways :thumbsup: