TEST: Velocity comparisons of PRB WITH and WITHOUT an OP wad

[roundball]

This morning I tested the effects that an Oxyoke over powder wad might have with a PRB load. Oxyoke advertises that using their wad will improve accuracy by reducing group size due to lower standard deviation from shot to shot, and the test proved that to be true.

But, I had also expected the same improved gas sealing properties which produced better shot to shot consistency to produce higher velocities from increased pressure building up and being sealed behind the wad, but was surprised to find that was not the case...velocity was actually a little lower using a wad.

TEST COMPONENTS
GM .62cal/.20ga Flint ”˜Rifled’ barrel
100grns Goex 2F
.020" Oxyoke prelubed pillow ticking
.600"/325grn cast lead balls (Eddie May/Georgia)
Wiped the bore after every shot
Pact Pro MK5 Chronograph at 15 feet

WITHOUT an Oxyoke wad over powder
Average velocit y= 1270 fps...higher velocity
Standard Deviation = 25 fps...pretty fair amount of deviation

WITH an Oxyoke wad over powder
Average velocity = 1232 fps...velocity averaged 38 fps slower
Standard Deviation = 6 fps...standard deviation improved significantly

 

[nchawkeye]

My guess is that the added weight of the wad decreased velocity a bit...

 

[Blizzard of '93]

seems odd, but that ain't much fps diff considering size (325gr) of the ball.

 

[Croppy Boy]

If your ball/patch combination is real tight, would an over powder wad really make any difference?

 

[roundball]

My guess is that the added weight of the wad decreased velocity a bit...

Its the only thing that was changed but I swear those little things are as light as a feather...surprised it would have slowed the payload down that much.

Seems odd, but that ain't much fps diff considering size (325gr) of the ball.

Right, but I was just surprised it was lower at all...as I said I assumed the "sealing characteristics" of a wad would have allowed greater pressure to build behind it...guess not

If your ball/patch combination is real tight, would an over powder wad really make any difference?

Well, as advertised, in addition to acting like a firewall to protect a patch, the wad is supposed to give better shot to shot coinsistency which it did in these tests...SD dropped all the way down to an average of 6 fps from shot to shot.
My PRB combo is very tight...GM .62cal bores are really .610's, not .620's...I use a .600" + .018" patch...takes a few good smacks on the short starter to get it down 6" then some muscle to seat it on down.

 

[Croppy Boy]

My guess is that the added weight of the wad decreased velocity a bit...

I wonder if you tried an over shot card instead to reduce weight.

 

[roundball]

My guess is that the added weight of the wad decreased velocity a bit...

I wonder if you tried an over shot card instead to reduce weight.

I'm not actually trying to fix a problem or do anything to increase velocity...just testing some existing things like wads, following a conversation here a few months about them, sharing the results, etc :wink:

 

[tg]

If the ball left the barrel at 1273 fps with the wad and left the barrel at 1223 fps without the wad, and the sun was low in the western sky what time would the 8:04 train from Chcago arrive in New York?

 

[tg]

"If your ball/patch combination is real tight, would an over powder wad really make any difference? "

I know it will hold a tighter group in a smoothbore with the wad, at least it has in a few of the smoothies I have played with.

 

[roundball]

If the ball left the barrel at 1273 fps with the wad and left the barrel at 1223 fps without the wad, and the sun was low in the western sky what time would the 8:04 train from Chcago arrive in New York?

Now be nice...
:grin:

 

[tg]

Just yankin' yer chain...do you think those oxyoke wads are soft enough to act as a cushion of sorts? do you have any hard fiber wads or any over powder cards to test with? the results were very interesting, thanks for sharing them they give me a general idea what my smooth rifle is doing for velocity it's not to far from what I had figured a bit faster actually. I've tried shooting and counting thousand one... till I hit the clanger but the results have been poor.

 

[roundball]

Do you think those oxyoke wads are soft enough to act as a cushion of sorts?

Yes, I use 1 or 2 Oxyoke wads 99% of the time for smoothbore shot loads...BUT...I spent 3-4 range trips a cpouple years ago tring to figure out why I'd keep getting an occasional 4-5" flyer when using PRBs in my .54 and .62 smoothbores...ultimately discovered it only happend when I'd use an Oxyoke wad under a PRB...tried 2 and even 3 wads stacked up but always got a flyer maybe 1 out of every 6-7 shots

Do you have any hard fiber wads or any over powder cards to test with?

Yes, in fact I was going to include tests with some Circle Fly 1/2" cushion wads but got to the range and realized I'd left them home.

I've tried shooting and counting thousand one... till I hit the clanger but the results have been poor.

:grin: ...SD must be all over the place

 

[paulvallandigham]

Roundball: If you send me your address, I will be happy to send you some 20 ga. OP wads for your testing. I have a couple of boxes I am not using. I also have 20 gauge cushion wads I cannot use, too, if you would like them.