Muzzle Velocity: Filler versus No Filler

[Foto Joe]

A few days ago in a different thread I mentioned that it made sense (to me) that filler could/would act as a defacto "Gas Check". I made this statement after veiwing high speed video of a BP gun being fired and noticing that a LOT of gas exits the barrel long before the projectile. To me it would stand to reason that if you could keep that gas or a portion of it behind the projectile instead of in front of it, you would get a higher muzzle velocity. How much higher I didn't have a clue, so off to my favorite box canyon down the road with the chronograph I went.

All shots were fired from a Pietta 1860 Sheriff Model with a 5" barrel. The charge was 30gr 3f Goex by weight and the rounds that used filler had 10gr by volume of Cornmeal. I will be repeating this test with a Dragoon as well, but the preliminary results do show that filler does appear to increase muzzle velocity slightly, in this case it was an average of 5%. Granted that doesn't sound like much but as the Mythbusters say "It's a result".

Average Muzzle Velocity without filler: 727 fps with Muzzle Energy of 164 ft. lb.

Average Muzzle Velocity with filler: 764 fps with a Muzzle Energy of 181 ft. lb.

I'm thinking a longer barrel could do one of several things, like prove or disprove the theory. If it proves the theory I'm thinkin' that the results will probably be more pronounced.

If a longer barrel dis-proves the theory, then I'll probably just go lie down by my dish until I'm struck by yet another epiphany.

 

[Noz]

"If a longer barrel dis-proves the theory, then I'll probably just go lie down by my dish until I'm struck by yet another epiphany."


I do that frequently!

 

[[email protected]]

This test was done many years ago. It was written up in "Muzzle Blast"
mag. The results were what you noticed. Also the shot to shot varance was
lower with the cornmeal. History does repete it'self.

 

[Foto Joe]

I didn't post the "Extreme Spread" numbers simply because they were a little embarrassing. The no filler spread was 153 and the with filler spread was 143. I attribute these high numbers to the fact that the powder compression was probably not the best. The Sheriff Model has that cute little loading lever on it that makes ramming the ball a pain.

I know from loading cartridges that uniform powder compression is one key to consistant velocities from Black Powder charges.

 

[Hanshi]

I don't know about revolvers but in chronographing rifles with and without an op wad, I discovered both lower shot-to-shot variation and modest velocity increase using a wad.

 

[[email protected]]

I read a test in "Muzzle Blast" where they load the cylinder with the same
pressure on each chamber. Then they just loaded with the bulit in rammer
on the revolver. The revolver was shot at 50 yds from a "Ransom" rest.
The group loaded on the gun was 6 inches larger than the one with the same
pressure. That's why on my custom revolver, it has a built in stop so I can load each chamber with the same amount of pressure on the powder. On a chronograph mine shows a 30 fps vararation from shot to shot.

 

[Foto Joe]

I figured out "real" quick when I started loading cartridges. I began by using a homemade compression rod made from a dowel. Then switched to a compression plug from TOTW. Niether would provide for a uniform compression, just what ever felt right.

I finally bit the bullet so to speak a few months ago and order a compression die from MidwayUSA that has interchangable plugs which can be set for depth. Now when I'm loading cartridges I'll set the 44 Special for instance so that at the bottom of the press stroke, it provides the depth/compression on the brass that I want. As long as the powder volume/weight is consistant then the compression is consistant.

 

[PapaG]

Started using cornmeal at Friendship in the sixties with a 44 c&b. Main reason was to fill the chamber after only putting in about 18 grains of powder (best accuracy load). I put a felt wad soaked in tallow on top of the powder, then filled chamber to mouth with cornmeal and then seated ball tight.

 

[mykeal]

What are the chamber diameters and the bore groove diameter on your pistol? Wouldn't that be more important to keeping gas behind the ball than loose filler?

 

[PapaG]

I always chose a ball (cast my own) that was big enough to shear a ring of lead off when loading.

 

[72coupe]

Those are pretty big ES. I have only chronographed my 58 Remington 1 time and I got outstanding results. I got a velocity of 950 with an SD of 9 for 10 shots.

My load was 30 grains by volume of Pyrodex RS, a Remington 11 cap and a Lee 200 grain conical.

 

[Oyeboten]

Hi Foto Joe,


This is very interesting.


I bought some 'Cream of Wheat' awhile back, thinking to try it ( for the BP Cartridges, I already know it is great for Breakfast! ) but, just sort of forgot about it.

Now I will definitely try it, and, chrono my results with and without.


5 percent increase in FPS for the same ( less than full ) charge, to me is 'Respectible'.

 

[[email protected]]

What your going to find out is that the velocity with "Cream-of-Wheat" is
going to be greater than if you used powder in place of it. I know how this
sounds, but it's true, and "Cream-of-Wheat" is cheaper than powder. Were
talking Black Powder here, Goex or Swiss.

 

[Curator]

28 grains of FFg and 12 grains (measure) COW gives the same or slightly more velocity (880fps) in my Pietta '58 Remington than 38 grains of FFFg and the same .454 round ball. It also burns cleaner and gives much better accuracy.

 

[J-Bar]

I have seen tables comparing velocity out of 5.5 inch barrel with a 7.5 inch barrel, and the 7.5 inch was lower. You never know until you chrono, but don't be shocked if you find that's the case.

 

[Foto Joe]

Wouldn't that be more important to keeping gas behind the ball than loose filler?

I don't have the numbers in front of me but yes, the chambers are not the same or larger than the grooves, but I haven't found a GS that I trust to ream the chambers as of yet. But...

I don't know about Cream of Wheat but Cornmeal compresses into a pretty respectable plug, it's not loose. I ran into some re-enactors last winter in Texas that basically used Cornmeal to top off their blanks because it compresses pretty solid. My theory is that the Cornmeal, even though yes some is going to escape past in the grooves, at least puts more pressure behind the projectile. Of course, this is NOT in any way a scientific test and I'm not standing on my soap box promoting this as gospel. I'm just making an observation about what I have found through my preliminary tests. Your results may vary.

Mykeal,

Keep in mind, I agree with you 100% on the chamber diameter vs. groove. I just don't have the resources or location to fix the problem at this time. You've been doing this a lot longer than I have without a doubt and I respect your opinions. I'm just throwing something out there for folks to think about.

I have seen tables comparing velocity out of 5.5 inch barrel with a 7.5 inch barrel, and the 7.5 inch was lower. You never know until you chrono, but don't be shocked if you find that's the case.

I'm going to have to disagree with that one simply because of my chronograph results from a '94 Marlin using 26gr 3f Swiss in 44 Special rounds. I was surprised to find that that medium load which yields numbers in the 700 fps range out of a revolver pushed a 200gr RNFP out at just under 1,100 fps. I figure if I crammed a 44 Mag brass full I'd see north of super-sonic on those.

Of course this is all subjective as I haven't chronographed a longer barrel like the Dragoon with that load yet. If I'm proven wrong it definately won't be the last time.

I think that's part of the fun of this whole thing that we do. We get to learn as we go along and usually don't have to worry about blowing ourselves up in the process. Case in point I upped my 38 Special (smokeless) loads up a few tenths of a grain yesterday when I loaded them. I was extremely paranoid when I set the powder dispenser because I was within two tenths of a grain of "Never Exceed". Every 7th load got weighed and if I pulled the handle on the measure and it bound or crunched at all, I dumped the charge and re-did it. At least I don't have to sweat the grains by the tenth on Black Powder.

 

[Oyeboten]

Well...I will figure to try Cornmeal, and, Cream o' Wheat also.

Being Winter and all, some Corn Meal Mush would be nice to have for Breakfast, too, for that matter, with Butter and Maple Syrup, couple Eggs over easy, some 'Jimmy Dean' Pork Sausage...Mmmmm!


Very interesting that the 'filler', in taking the place of some of the Powder which would have been in a full Load, seems to take the place just the same or better, than if it had been 'Powder'.

I guess it helps that much in eliminating early Blow-By and or who knows what else.


This is really good to know.


Thanks Foto Joe for bring this up.

 

[Foto Joe]

Very interesting that the 'filler', in taking the place of some of the Powder which would have been in a full Load, seems to take the place just the same or better, than if it had been 'Powder'.

I think you may have misunderstood the test. The filler DID NOT take the place of any powder. Both the control and the test were loaded with 30gr by weight of 3f Goex. The Cornmeal filler was in addition to the powder charge. I would have like to have used at least 15gr by volume of filler, but the 1860 chambers didn't allow for more than 10gr of filler, which was measured by volume only as Cornmeal is significantly lighter than powder.

By the way, Cornmeal Mush for breakfast?? Yuck!! Of course it is the healthiest portion of your meal I guess, but what the heck. My grandma lived to within 2 weeks of her 100th birthday eating bacon, lard and all those bad things. The way I figure it, if my cholestoral drops below 220, I'm heading for the closest McDonalds!!

 

[J-Bar]

It's true that velocity out of a 7.5 inch barrel will USUALLY exceed velocity out of a shorter barrel, but sometimes stuff happens. The tables I was referring to are in John Taffin's "Action Shooting Cowboy Style":

Page 160: seven different brands of commercial .38 special ammo, velocities from a 5.5 inch Great Western revolver exceeded velocities from a 7.5 inch Great Western revolver. For example Black Hills 158 grain from the 5.5 was 773 fps, from the 7.5 was 692 fps; Federal 158 from the 5.5 was 843 fps, from the 7.5 was 776 fps, and so on.

Page 164: 3-D 240 grain .44 Magnum load clocks 921 fps out of a 6.5 inch Blackhawk, but 909 fps and 905 fps out of two different 7.5 inch Blackhawks, respectively.

Page 178: Bull-X 250 grain .45 Colt over 6.0 grains of N-100 gave 876 fps from a 5.5 inch Colt New Frontier, and 848 fps from a 7.5 inch New Frontier. The 5.5 inch barrel gave higher muzzle velocities for three other powders also; Red Dot, Titegroup, and W231, but the 7.5 inch gun gave 895 fps versus 892 out of the 5.5 inch gun with Unique.

Page 179: those same powders and the same bullet were compared in a 4.75 inch Great Western and a 5.5 inch Great Western, and all five loads came out of the 4.75 inch barrel faster than the 5.5 inch. Not much, 4 or 5 fps in each case, but consistent.

Page 180: These same loads were fired in a 3.5 inch Cimarron New Thunderer and a 4.75 inch Cimarron Model P, and in each case the muzzle velocity out of the 3.5 inch barrel was higher than the 4.75 inch barrel, by about 40 fps.

Page 201: 5 different .32-20 loads were tested in a Cimarron 4.75 inch and a Cimarron 7.5 inch with mixed results. The shorter barrel gave a higher muzzle velocity in 2 of the 5 cases. 4.0 grains of Unique under a Bull-X 115 grain bullet clocked 810 from the 4.75 inch and 798 from the 7.5 inch barrel. 4.7 grains of AA#5 gave 736 fps from the shorter barrel and 732 fps from the longer barrel.

Page 208: .44 Special loads; out of 5 different loads, velocity from a 4.75 inch Cimarron Model P was higher than the velocity from a 7.5 inch USFA gun, 30 to 70 fps.

Page 224, .38 Long Colt blackpowder loads. A 5 inch Cimarron 1851 Navy gave higher muzzle velocity than a 7.5 inch Great Western 3 out of 5 times shooting the same loads.

Page 226: .38 Special blackpowder loads: 12 different black powders were tested in a 5.5 inch Great Western and a 7.5 inch Great Western. In each of the 12 comparisons, the shorter barrel gave the higher muzzle velocity, about 30 to 40 fps.

I can't explain it. I just remember thinking how weird that was when I first saw these tables. Undoubtedly there is more to muzzle velocity than barrel length.

I will be very interested to hear your range report.

 

[Foto Joe]

J-Bar,

Ya just never know do ya?? When I first started reading your post (which you took a lot of time to research by the way), the first thing that registered with me was the loads were smokeless, but of course the last two were Black Powder.

I'll start a new thread and reference this one when I get around to testing.

 

[junkman_01]

Maybe the longer barrels provide more friction to the bullet than the shorter ones, thereby slowing them down a bit. I know for a fact that this occurs with .22 rifles with barrels over 18 inches. Just a thought.

 

[madcratebuilder]

That's why on my custom revolver, it has a built in stop so I can load each chamber with the same amount of pressure on the powder.

+1

What little very informal testing I have done confirms this for me. Consistent loading pressure has a major effect on accuracy.

The testing I have done using filler was inconclusive with the revolvers I used. That may be from chambers matched to the barrels.

 

[TheRodDoc]

Tests using different revolvers with different barrel lengths would not prove much.

For barrel gap, forcing cone size and shape and if the chamber has a beveled mouth or not can affect velocity greatly.

Also ball or bullet fit in barrel.

Cylinder gap alone can up velocity by as much as 100 fps per each .001" the gap closes.

The position of the ball in the drawing is where gas can blow bast the ball.

View attachment 135792

Also the reason some of you say the velocity goes up when compressing the powder is that you are breaking some of the powder granules into smaller pieces, (finer powder) If you are consistent in your compression then each chamber will have a similar amount of finer crushed powder in them and all will have a closer velocity.

 

[Oyeboten]

Hi Joe, all,



What I was getting from the decriptions, is, say, if in .45 Colt Cartridge, if one were to use 30 Grains BP, and, 10 Grains Vcolumetric-equiv of Corn Meal...that, the Velocity would be the same or a little better than if having used 40 Grains BP and no Corn Meal.


Is this correct then?


Or..?

 

[mykeal]

Maybe.

If the chambers were much smaller than the groove diameter, the filler and extra 10 grains of powder would both be expelled, essentially acting as a kind of 'gas impediment'.

However, if the chambers were larger than the groove diameter, the extra powder would not be expelled and would more than likely thus be burned since it couldn't escape by the ball, resulting in more velocity. The filler would, of course, not burn, but rather just follow the ball out of the barrel.