sjf said:
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