.40cal Flintlock PRB - Velocity Tests

[roundball]

VELOCITY TESTS - .40cal Flintlock

Pretty significant velocity gain of 100+ fps for each 10 grns increase of Goex 3F...and it gained more exponentially at each powder charge increase.
80grns was really it's magic efficiency threshold then it choked hard at 90grns.
This is a terrific Flintlock caliber and one of the least expensive to shoot.

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

 

[J.D.]

That is interesting. That 80 gr charge is a screamer.

I am in the process of building a Sw VA rifle using a Rice 44", 40 cal, A wt barrel, so I wonder how those velocities would corrolate to a longer barrel?

Interesting results though.

 

[roundball]

Yeah, if you look at the progression from charge to charge, the velocity increase gets large in a non linear way...each step is as large as the step before it PLUS some more...until it hit the wall at 90grns.

So far I've only used the .40cal for plinking at the range with 30 & 40grn charges...so my next test with the .40cal will be to see if its still accurate with 80grns.

Dunno about 44" barrels...my longest are 32" T/Cs and 33" GMs

 

[J.D.]

I will conduct similar tests on the longer barrel after the gun is finished. This is my first attempt at building a gun from a blank, so it may take a while. :v

 

[Larry Pletcher]

Roundball,
It doesn't seem to take much to get the ball supersonic does it. In a test where I wanted to get a photo of a patch separating from the ball I loaded down to 1000 fps so that every .001 of a second represented 1 foot. (It helped to aim the camera.) I think the final load was 20 gr, but it could have been as low as 15. I'll try to find my load.

Also, I saw a 2000fps with a .40 out of a 42 in Douglas barrel. Cool caliber! I think it's the 22-250 of the ML world.
Regards,
Pletch

 

[roundball]

Yes, its like a little 92grn laser-ball for sure.

(also, note the velocity of the little 15grn solid rubber practice ball with only 50grns 3F)

Now that I finally got my chronograph out of the box and into operation...(date on the sales receipt is the year 2000 :shake: )...I'm going to walk up through the calibers this summer...planning to do the .45cal Monday.

 

[nchawkeye]

JD...For what it's worth, I use 25gr of Goex FFF for squirrels in my .40 and it shoots flat to about 50 yards...If you are planning to use it for squirrel hunting that's a good place to start...

 

[kevthebassman]

Roundball keep 'em coming. I'm really curious to see the velocity of a .54.

 

[11th corps]

Good stuff roundball
I had my .40 out at the range this a.m. It is accurate. I have not loaded mine hotter then 50 grains and probably will not. But it is interesting to see what your gun is doing with hotter loads.

 

[Swede50]

What brand of flint lock are you shooting the 40 out of? Do you find the TC Flint Lock to be reliable?

 

[roundball]

What brand of flint lock are you shooting the 40 out of? Do you find the TC Flint Lock to be reliable?

The barrel is a .40cal 15/16" x 33" x 1:48" made by GM as a "drop-in" for a TC Hawken stock...TC significantly redesigned their locks in the mid 90's and they are outstanding.

I have several and have yet to have a single problem with any of them...get very long flint life out of them using Tom Fuller 3/4"x7/8" black english flints.

Shooting and hunting these flintlocks year round is my main hobby and I wouldn't waste my time and money going to the range if my TC locks weren't 100% reliable.

 

[MSW]

Roundball-

Thanks for the post! does this data represent single shots? it appears that there are some burps in the curve, but i think if you had more data (i.e. made more smoke) the curve would smooth out... just a thought. anyway it's nice to see this kind of stuff being done.

By the way- the older (about 1983 T/C flintlock is pretty reliable- i've yet to have a lock failure that was not my fault (i.e. flint neede work, pan not primed, etc.)

thanks again

 

[CoyoteJoe]

JD, the old first edition Lyman BP Handbook lists a .40 caliber with 43" barrel at 2255 fps with 80 grains of the old Gearhart-Owen 3f. That is quite a bit faster than Roundball's results from his 33" barrel and even more pronounced when you look at energy figures, 1037 ft.lb from Lyman's data versus 560 from Roundball's. Of course the powder may also be slightly different from that Lyman used in 1974 but no doubt you will see significant gains from the longer barrel.

 

[roundball]

Roundball-
"...does this data represent single shots?..."

5 shot averages

 

[roundball]

Yes, I noticed the differences in velocity just with TC's load data charts...all my test results were slower than TC's...the things that make me wonder about it are:

I read somewhere that there is even a difference in velocity between the muzzle exit and a mere 15 feet away...maybe somebody here knows something about that;

I'm using a Flintlock but I suspect TCs load data is from a caplock, or maybe even a special test barrel, so there may be a lower velocity form a Flintlock vs. a caplock; (another good test to run this summer)

And TCs tests were done way back in the 70's...almost 40 years ago...no telling what the powder characteristics were back then.

Interesting stuff...was planning to run .50cal Flintlock tests tomorrow morning but now I'm wondering if I might want to use an identical .45cal caplock for comparison right now :hmm:.........nah.......I'll stick with my game plan and run through all the flintlock calibers first...

 

[JeffinNZ]

That's awful slow for the charges. I guess that's the GOEX powder then.
I am burning 45gr of 3Fg Swiss in my flintock with a 38 inch Colerain and getting high 1700's. In the percussion gun with a 33 inch barrel it produces 1950fps.

 

[roundball]

Yes, Goex.....apples and oranges comparing it to Swiss with it's different granulation burn rates, etc

 

[Tumblernotch]

You're losing some of the gas through the vent in a flintlock. I don't know how much that affects it, but I'm sure it's similiar to the loss in a gas-operated semi-auto as compared to a bolt action. Just a thought. :hmm:

 

[roundball]

I fully expect you're right...I don't have a .40cal caplock to run comparison tests but I do have identical caplocks in .45/.50/.54 and eventually will run identical comparison tests with them to see what the difference might be

 

[Tumblernotch]

I have a .40 percussion with the same barrel under construction but that project is on the back burner for now. Whenever I get it done and can get ahold of a chronograph that will be an interesting project.