TEST: PRB velocities from 100 & 120grns Goex 2F

[roundball]

Velocity comparisons between 100 & 120 grains Goex 2F was only 70 fps.

GM .62cal/.20ga Flint ”˜Rifled’ barrel
.020" Oxyoke prelubed pillow ticking
(no wad)
.600"/325grn cast lead balls (Eddie May/Georgia)
Wiped the bore after every shot
Pact Pro MK5 Chronograph at 15 feet

100grns Goex 2F
Average velocity = 1270 fps
Standard Deviation = 25 fps

120grns Goex 2F
Average velocity = 1340 fps
Standard Deviation = 35 fps

 

[BrownBear]

Have you transfered those #'s to a ballistic table to check differences at 50 and 100 yards? I bet it's a sinful waste of powder.

 

[roundball]

Have you transfered those #'s to a ballistic table to check differences at 50 and 100 yards? I bet it's a sinful waste of powder.

No, sure haven't...the chrono has that stuff built in but this was my first time out with it and I'm just learning to use it, only played with the velocity & SD features today...I needed a .62cal to shoot whitetails at 40 yards like a needed a hole in the head...but you know how this hobby is :wink:

 

[Little Wattsy]

Have you transfered those #'s to a ballistic table to check differences at 50 and 100 yards? I bet it's a sinful waste of powder.

No, sure haven't...the chrono has that stuff built in but this was my first time out with it and I'm just learning to use it, only played with the velocity & SD features today...I needed a .62cal to shoot whitetails at 40 yards like a needed a hole in the head...but you know how this hobby is :wink:

:haha: :haha: :haha:
There is NO SUCH THING as excess in the hobby / sport of shooting! :hatsoff:

 

[BrownBear]

Just did a Q&D calculation and 70 fps translates into about 45 mph. Consider that a pitcher's fastball isn't even notable till it tops 90 mph and a picture starts to emerge.

If you were hucking a baseball 45 mph would barely qualify as a lob and 70 fps would take more than a second to get from pitcher to catcher. Having been hit by more than a few fastballs myself, a 45 mph lob isn't going to hurt much unless it hits you in the head or the huevos.

How many grains does a baseball weigh, anyhoo?

 

[thewho66]

Just a general thank you for taking the time to work this stuff up. I am looking forward on the .40cal test, Ive been wanting to get the 38inch GM barrel for my renegade. :thumbsup:

 

[roundball]

"...wanting to get the 38inch GM barrel for my renegade..."

Just some feedback on considering a 1" x 38" x .40cal barrel.

A couple people have bought them just in a 15/16" barrel and sold them shortly thereafter because they weighed a ton. When I was getting ready to buy my 15/16" x .40cal I worried about the weight of the 38" and asked around, had a couple guys respond that they're too heavy so I just bought the 33" version and glad I did as it's quite heavy as it is.

I can't even IMAGINE how heavy a 1" x 38" x .40cal barrel would be in a Renegade...just mentioning this to be sure you think it through.

 

[Geraldo]

Posted by Roundball:

I needed a .62cal to shoot whitetails at 40 yards like a needed a hole in the head...but you know how this hobby is

As much as I admire your scientific testing, you are obviously ignorant of one of the most crucial mathematical formulas extant. To determine the proper number of rifles for one person to won, use the following formula:

X+1=N
X is the number of rifles you currently own, and N is the number of rifles you should own.

 

[roundball]

:rotf:

 

[smo]

142 to 149 grams with 108 red stitches :hatsoff:

 

[BrownBear]

So let's see here....

At a little over 15 grains per gram, that would be something over 2200 grains. And yup, at 140 fps it sure does smart. Probably wouldn't take much offense to it at 70 fps, though. If the RB weighs something over 300 grains and is traveling at 70 fps, who's to notice?

 

[Joel/Calgary]

Strictly speaking, energy is a better measure of powder efficiency than velocity. If I did this right, you got an 11.3% increase in muzzle energy out of a 20% increase in powder. It looks better but still not a great payoff, and that still doesn't address energy at some distance downrange.

I do appreciate your work in testing and your publishing it.

And I may have to see about getting a few hundred of those .50 rubber balls.

Joel

 

[roundball]

Strictly speaking, energy is a better measure of powder efficiency than velocity. If I did this right, you got an 11.3% increase in muzzle energy out of a 20% increase in powder. It looks better but still not a great payoff, and that still doesn't address energy at some distance downrange.
I appreciate your work in testing and your publishing it.

I understand what you're saying...I'm just getting into this chrono stuff, concentrating more on learning how to "execute" all the aspects of the chronograph operation, and establishing baselines for the various calibers, etc...than really getting into the analysis side of it yet...just sort of in the mode of "what are my Flintlocks doing with what I use today", etc.

And I may have to see about getting a few hundred of those .50 rubber balls.

I just sent 300 to a neighbor up in Ontario and am down to a critical mass of my own...however, you can order these directly from PAI (Precision Associates, Inc) in Minnesota...I'll go get the Email contact name and post it here for you

 

[roundball]

.50cal solid rubber balls, $70/1000

Customer Service Supervisor
Precision Assoc., Inc.
740 N. Washington Ave.
Minneapolis, MN 55401
Ph: (612) 334-9120
Fx: (612) 334-9288
[email protected]
http://precision.thomasnet.com/vie...c-rubber-balls/molded-rubber-balls?&forward=1