Chrony Results: .45 BPM

[ClemBert]

You must be taking about this bullet mold that is used to make the subject bullet. I don't cast my own bullets for now. Perhaps some day. If someone wants to send me a batch of them I'll test them in the .45 BPM. I'm not necessarily buying into the less recoil aspect of the discussion. I've shot 48 grains of FFFg and a 250 grain bullet as well as 55 grains of FFFg and a 150 grain bullet. On the one hand a 150 grain bullet is lighter than 250 grains but on the other hand you are shooting it with 55 grains of BP versus 48 grains. They seem to offset each other.

From the point of "equal and opposite reaction" one load's bullet energy is 591 ft-lbs while the other's is 577 ft-lbs. Like you said, good thing a Walker weighs 4.5 lbs.

Something tells me Foto Joe's Dakota clone weighs a bit less than 4.5 lbs. No wonder he uses the name "ClemBert" as a cuss word whenever he shoots those 40 grain .45 Colts. I told him they were "fun" loads.

 

[Foto Joe]

I'm still waiting to hear your theory as to why you're still thinkin' this.

For no other reason than I would have thought you could get a better speed out of the BPM. That said, it's still extremely impressive to get as much velocity as you have out of a Black Powder revolver.

I'll just wait for you to load up some 40 grain GOEX loads and let me know the drop in velocity.

I've tried it and there's a little problem with that. Given that Swiss is about 10% heavier/denser than Goex, I found it almost impossible to stuff all 40gr of Goex into the brass and still be able to seat the bullet. Of course I wasn't using a compression die at the time, all I had was that compression plug from TOTW.

Now that we know how fast they go, when are we going to find out how accurate they are?

 

[ClemBert]

I think the BPM is limited in this particular Walker. The most limiting factor is the barrel length, I believe. Now if I could slap on a 12" or an 18" barrel off of a buntline we'd be in business.

Now that we know how fast they go, when are we going to find out how accurate they are?

Accuracy?....Hell, just the boom and all that smoke is likely to give any critter a heart attack and fall over from shear fright. No need to maim the lil' fella!

I'd like to think if I quit shakin' in my boots and flinchin' as I'm about to pull the trigger I'd come close to hittin' an evil good fer nothin' tin can at 25 yards.

 

[arcticap]

I'm curious about the how the velocity of .45 BPM cartridge compares to the velocity of the original Walker percussion cylinder when loaded with the same size bullets and amount of powder.
How much velocity is gained?
That's one way to measure what the pure gain is in performance by converting one's Walker to the .45 BPM.
The desire for even higher velocity over what has already been attained doesn't answer how much of an increase has already been achieved just by simply converting.
If any of that comparative data can be shown then folks could see what the actual gain is by having their gun converted.
What are some of the estimated or actual velocity gains for any of the various bullets? For instance, how about when loaded with 50 or 55 grains of powder?

 

[ClemBert]

I'm curious about the how the velocity of .45 BPM cartridge compares to the velocity of the original Walker percussion cylinder when loaded with the same size bullets and amount of powder.
How much velocity is gained?
That's one way to measure what the pure gain is in performance by converting one's Walker to the .45 BPM.
The desire for even higher velocity over what has already been attained doesn't answer how much of an increase has already been achieved just by simply converting.
If any of that comparative data can be shown then folks could see what the actual gain is by having their gun converted.
What are some of the estimated or actual velocity gains for any of the various bullets? For instance, how about when loaded with 50 or 55 grains of powder?

Those are good questions.

Keep in mind, the goal of the .45 BPM was to have a cartridge version of what was available to a Walker in cap-n-ball mode. In other words, a mechanism to get beyond the 40 grain limitation of a .45 Colt converted Walker. My intention was not to exceed what a Walker in cap-n-ball mode was capable of. That was the point of using a 150 grain bullet....to match as close as is reasonably possible to a 141 round ball load. I have no expectations that a 150 grain bullet with 60 grains of BP will exceed the performance of the cap-n-ball equivalent...although it may...or it may not.

The experiment you ask for is on my list. I just purchased the chrony so I had not had a chance to measure the Walker with 55 or 60 grains loads and a round ball in cap-n-ball mode. Most likely I would only do some chrony measurements for 141 RB on top of 55 and 60 grain loads. I have no plans to do conical type testing.

Although it would not be an exact one-to-one comparison I wouldn't mind hearing some Walker chrony results from others to understand about what I should expect.

 

[TheRodDoc]

Have you considered the cyl. gap? It can be loosing up to 100 fps / .001" of gap.

To test, place empty unprimed case in bottom chamber and slide a thick enough feeler gage in behind that empty to hold the cyl. ahead against the forcing cone. No gap. See how much it gains.

I would also not compress the powder at all. Bullet just sitting on settled powder. no wad for a test at least.
I would think crushing the powder as much as you have been doing is forcing the powder to burn from one end to the other of it's length in chamber by not letting the flame travel around and through the powder granules to ignite it all quicker.

 

[ClemBert]

I'm curious about the how the velocity of .45 BPM cartridge compares to the velocity of the original Walker percussion cylinder when loaded with the same size bullets and amount of powder.
How much velocity is gained?

Since I don't have my own data yet I'll borrow some data from when I first asked about chrony results for a Walker.

For what it's worth, here is a bunch of data from a Uberti Walker. The measure is one of those adjustable volume things that seem to be calibrated for Goex. Swiss powder thrown from the same measure weights a few grains more due to density but when weighed, Swiss is still "hotter" than goex.

As to calibration, all I know is that I have used two chronographs on the same day on more than one occasion and the readings were very close together.

I note no fall off in accuracy between 55 and 60 grain charges or from one type of powder to the next but attempting to use very light charges could result in wild velocity variations because projectiles really need to be set down on top the powder column with possibly a bit of compression to get consitent ignition and burn. I have tried various combinations with and without overpowder wads finding no significant difference in velocities or round to round consistency. The better treated wads will keep the barrel clean for extended firing while leaving them off is ok too if you clean out the (considerable) powder fouling after shooting a chamber full. A cursory pass or two through the bore with a spit patch will do the trick.

Walker-Uberti

Charge Velocity Extreme Spread
{5 rounds}
140 Grain Ball
55 Gr/Vol Goex FFFg 1001 fps 54
60 Gr/Vol Goex FFFg 1115 fps 46
60 Gr/Vol Pyrodex P 1221 44
60 Gr/Vol A Pioneer 974 80
60 Gr/Vol Swiss FFFg 1278 53
55 Gr/Vol Swiss FFg 956 46
60 Gr/Vol PyrodexRS 1045 35
37 Gr/Vol H 777 1201 72

200 Grain Lee Bullet
40 Gr/Vol Goex FFFg 927 40
45 Gr/Vol Swiss FFFg 1074 33
45 Gr/Vol Pyrodex P 1087 47

170Grain Original Pattern Picket Bullet
40 Gr/Vol Swiss FFFg 1031 36
Energy 402 ft/lbs
45 Gr/Vol Goex FFFg 1026 84
45 Gr/Vol Swiss FFFg 1158 35
Energy 506 ft/lbs
45 Gr/Vol. Pyrodex P 1035 57

An Ed SANOW article from a Feb '98 issue of HANDGUNNER mag lists a vel of 1287 fps w/ 60 gr BP and 141 gr roundball.

The article was entitled "BP Stopping Power" and they shot perc revolvers into gelatin as well.

The Walker, and the Dragoons, were the hands down winners.

My most recent data:



It would seem that my 141 grain roundball .45 BPM cartridge with 60 grains of FFFg Goex is comparable to the data above in the whole scheme of things. It tells me that the .45 BPM with 141 RB is doing pretty much what one would expect from a 141 RB with 60 grains of BP in cap-n-ball mode. That means....Mission Accomplished.

 

[ClemBert]

Have you considered the cyl. gap? It can be loosing up to 100 fps / .001" of gap.

To test, place empty unprimed case in bottom chamber and slide a thick enough feeler gage in behind that empty to hold the cyl. ahead against the forcing cone. No gap. See how much it gains.

I would also not compress the powder at all. Bullet just sitting on settled powder. no wad for a test at least.
I would think crushing the powder as much as you have been doing is forcing the powder to burn from one end to the other of it's length in chamber by not letting the flame travel around and through the powder granules to ignite it all quicker.

Yeah, I think it is time to go check the cylinder gap again and see if anything has loosened up besides the screws.

I thought it was pretty much a given that black powder performs better with some level of compression versus none....at least that what I've read from numerous posts on numerous forums. Of course the big question is "how much compression is optimal?". I'd like to think I'm compressing the powder not crushing the powder but there's no doubt that in some cases I've really worked too hard to get the powder in a space that's too small.

As I understand it. BP burns through contact. That is, granules start to burn when they come into contact with other burning granules. So compressing the powder to some degree helps this process by putting granules closer to other granules. The idea is that BP burns linearly. That is, from the bottom of the case and moving upward (at a very fast pace through deflagration). I don't think the BP burns by flames jetting out and lighting all the granules at the same time. Maybe someone would like to back me up or shoot me down....

 

[Oyeboten]

It would be easy enough to test the difference between Cartridges which have their BP compressed, and, those which do not, keeping all else equal ( but for Bullet Seating depth I s'pose).


Bear in ming if you do elect to try '777', that it is more powerful than GOEX by weight, and that it should not have any compression, so, un-compressed 50 Grains of '777' ought to be close to a compressed 60 Grains of Goex as for yield.


Swiss is also reputed to be about 10 or more percent more powerful than GOEX, where, it would be easy to make some comparitive tests with the two.


What is your Bore between the Lands of the Barrel?

 

[ClemBert]

The performance of the 55 grain FFFg cartridge wtih 150 grain Biglube actually went down. I guess there is a point when the powder has just been compressed too much. Did I squeeze all the oxygen out of the cartridge? The drop was fairly significant IMHO. 1392 ft/sec (1/8" compression) down to 1232 ft/sec (3/8" compression)...an 11% drop! That extra 1/4" of compression really dumbed it down.

Oyeboten,

I think I showed what over compression can do to performance. I have to admit that I had a cartridge where I mashed the bullet in too deep so I used a kinetic bullet puller to take it apart. On that particular cartridge I had compressed the powder to the point where it was powder was more like a giant pellet. I had to really dig at it to remove the powder.

The groove and lands diameter is less than impressive on an Uberti Walker.

Lands: 0.438"
Groove: 0.458"
Bullet: 0.452"

I really think I'm getting reasonable and expected results. If you look at the .45 BPM 141 grain RB numbers I referenced above you can see that I'm getting approximately what others see in cap-n-ball mode.

 

[Oyeboten]

There might be a sort of graduated scale of COmpression for BP -

No Compression

Some Compression

Optimum Compression

Too much Compression.


Tradition and old practice appear to advocate good Compression ( Lol...which I take it, means, enough but not too much or too little).


Probably the Ballistics advantage of the Conversion Cylinder will be for heavier Bullets.

Even though I know that was not your original intention necesarily, but, seems to me that with lower weight projectiles, I am not surprised that the FPS is on par with a non-Converted Walker.

250 - 300 Grian, and good Compression of the GOEX, is where I would expect higher FPS than a non-Converted WALKER.

 

[makos_goods]

Have you considered the cyl. gap? It can be loosing up to 100 fps / .001" of gap.

To test, place empty unprimed case in bottom chamber and slide a thick enough feeler gage in behind that empty to hold the cyl. ahead against the forcing cone. No gap. See how much it gains.

I would also not compress the powder at all. Bullet just sitting on settled powder. no wad for a test at least.
I would think crushing the powder as much as you have been doing is forcing the powder to burn from one end to the other of it's length in chamber by not letting the flame travel around and through the powder granules to ignite it all quicker.

roddoc,
I have to disagree with you on this. You need a refresher in Fluid Dynamics, specifically on gas flow. Go crack the books and get back to us.

A loss of 100fps/.001" is totally erroneous, where did you pull that from?

I need to look through my old files, but about 40 years ago (probably in the late 60's or early '70s) there was a good article in the American Rifleman about the effects of cylinder gap and velocity loss. This was a subject of interest at the time because of the introduction of the .22 Jet in the S&W 53. "Everyone" was convinced it was a losing velocity because of the revolver's cylinder gap. A chambered test barrel was constructed and they found there was NOT a significant loss as they expected. The author of the article set out to find just how much of a loss there was for each .001" of cylinder gap. He started with the cylinder literally butted up against the barrel face using shims and a yoke he sacrificed for the project. Then he moved it back in .001” increments until he reached .010”. He found the first .001” experienced a 3% loss in velocity. Then contrary to what anyone besides someone who understands gas flow, each additional .001” only experienced an incremental (not overall) additional 1% loss.

So if you started at 1,800 fps with zero gap you would be at 1,579 with .010” That’s a loss of 220 fps. No one in their right mind would run a revolver at “zero” so let’s extrapolate a bit and assume a “super tight” gap of .002” That means it would start at 1,728 (which is actually about right for a .22 Jet) and then end at 1,579 for a .01” gap that a loss of only 149fps or 8.6%. I have an interest in that info because I have built some improved short .22 K-Hornets on Smith revolvers, not the Kay-Chuk I had to be difficult and do it the hard way with a personal wildcat ( I was younger and more hard headed then…).

Then there are several articles that have been done using Dan Wesson revolvers because you can set the barrel gap. They have been done with the .44 mags, .357 and at least one with the .22LR. I had a “kit” model 15-V and I played around with it in the ‘80s. That’s what taught me the practical application of cylinder gap.

Here is an article from Shooting Times, June 1983 about a well done test with a Dan Wesson 22-VH. You will see the results were once again different than what the wives’ tales recount and even what the author expected.



ADDED 4/20

I couldn't find my older American Rifleman magazines but this report was originally published on THR a couple of years ago.

Notice how little it changes per .001". The .38 spl low pressure loads are what we should be looking at for BP, it is right in the velocities and corresponding pressures we discuss on this forum. The high pressure table is there to provide another set of data points. Notice how this correlates well with what I remembered from the American Rifleman article and correlates with the Dan Wesson test above.





So, Clembert I wouldn’t worry too much about your cylinder gap. The problem is the amount of BP and the barrel length to burn it in. You’ve run up against the wall of diminishing returns even with the fastest granulation that would be safe in that revolver. I will recommend that you compress the “tar” out of your loads and apply a very heavy crimp. Fill your case vibrate it down and add more if necessary, a drop tube might be called for. Then make sure you get at least 1/8” compression (more if you can get it).

BP is a very inefficient propellant, you get 60% uncombusted materials even with an optimized barrel length for the charge. So, only 40% of the charge is potentially converted into propelling gases and that once again assumes you have a tube long enough to take advantage of it. At some point you’re just spewing burning and unburned particles out the muzzle. It makes for “purty” night shooting and some hair singing results…

Try and compress it more and see if you can squeeze a bit more velocity out of it. Crimp it hard to help the pressure build a bit.

You seem like a bright guy, what is your training in? I have several friends who are engineers out of Clemson.

Regards,
Mako

 

[ClemBert]

Thanks Mako.

I'd have to admit my crimps tend to be on the lighter side. I generally have been doing the minimal amount to take "the flare" out after using the expander die. That last group of 50 rounds I did I went with a heavier crimp but I'm far from really mashing the crimp well within the crimp grooves.

I think my diminishing returns really kicked in at around 55 grains FFFg. As you said the relatively short 9" barrel of the Walker is a limiting factor. One of which I may be at or near with 55 grains. I'll try some loads with a heavier crimp next time. For the 60 grains loads I was using a 24" drop tube. Even if I find out that 60 grains is going beyond the "useful" amount of powder I'd probably keep a few loudenboomers around just for the smoke-n-boom effect.

Just for grins I measured the cylinder gap on a couple of my Ruger heathen revolvers. The Blackhawk had a gap of 0.010 while the SingleSix came in at 0.005. I was a bit surprised to see that larger gap on the Blackhawk.

You seem like a bright guy, what is your training in? I have several friends who are engineers out of Clemson.

Formal education would be Electrical Engineering. For a living I work as a consultant in the electronics industry. Specifically, designing ASICs (Application Specific Integrated Circuits) for many different computer/electronics related industries such as VOIP, RFID, video, set top boxes, etc. I'm one of the guys that design those little computer chips that contain millions upon millions of transistors.

 

[arcticap]

I think my diminishing returns really kicked in at around 55 grains FFFg. As you said the relatively short 9" barrel of the Walker is a limiting factor.

I think that the fffg powder [& it's brand] is also a limiting factor. Since granulation controls the burn rate, what about mixing in smallish, incremental amounts of ffffg?
Substituting very small percentage increases of it at a time should be safe to help extrapolate another velocity data curve.
There's ffffg fines in every can of black powder anyway, it's just that it's not separated and the percentage of it contained in each pound isn't obvious.
Maybe just enough ffffg can be added to each cartridge at first to make up for whatever velocity is perceived to be lost through the barrel cylinder gap.
Anyway, I don't believe that the maximum velocity has been reached yet without further testing.
Has Swiss powder even been tried, or another powder containing Alder charcoal?
It's a sporting powder that's most suitable for BP cartridges.

 

[ClemBert]

I think Swiss would be the next logical choice.

However, y'all are killin' me. I've matched what I believe the Walker does with 60 grains of FFFg and a roundball. But y'all want me to push that poor Walker even harder.

I'm all for pushing this thing until the barrel goes down range. After all, I'm on a closed coarse and that is what I built that test fixture for. But which ones of y'all are going to kick in for a new Walker to help poor ol' ClemBert out?

 

[makos_goods]

Clembert,
I suspected you were an engineer based on your methodology. You don't have to explain microprocessors to me, I spent 9 years in the semi conductor industry.

Crimping is gooooood...I am a believer in hard crimps with any revolver and especially with BP. I saw articaps suggestion about the duplex load, I have avoided them except with modern ordnance so I can't comment. Of course you can get more velocity with some of the substitute powders. It's a misconception that powder needs air space around it to burn. BP has it's own oxidizer and even with intimate contact the grains in contact will burn on their surfaces. There isn't any way you can compress it with your loading process to the point you will inhibit burning, in fact the opposite will be true with each opposing surface feeding and intensifying the opposite grain's combustion.

In closed vessel tests compressed powder has a higher conversion rate to gas and at a higher rate. Powder has to be fragmented to create the external surface area, but then benefits from close proximity and containment to achieve more efficient combustion.

Regards,
Mako

 

[makos_goods]

articap,
Did you know that willow actually has a higher energy content by weight than alder? I know the opposite is believed because of the better European powders. It's not just the charcoal, it's also the pre and post processing of that charcoal and the other two ingredients.

Have you ever inspected Swiss and Goex together under a microscope? You will see a notable difference.

Both Alder and Willow are in the lighter wood groups. There are lighter ones such as balsa and they have higher energy contents, they make a faster burning gunpowder which isn't as useful as a propellant. You can use almost any cellulose based material to make charcoal and there are even sugar powders. There is an "ideal" range for the energy content (which is primarily density based) of charcoal to make BP suitable for propellant. There are other forms which are more useful for blasting powder.

This is very much akin to nitrocellulose powders that each have a useful pressure curve and range. You wouldn't use a fast burning powder like Bullseye for a rifle cartridge, the same is true with charcoals there is a sweet spot for the 75/15/10 ratios of BP. Many people don't realize you can manipulate the weight ratios based primarily on the density of the charcoal to achieve the fuel/oxidizer and reaction modifier (sulfur) to achieve (within reason) a more consistent from lot to lot powder than simply and blindly mixing the 75/15/10 ratio by weight alone.

Well enough of that... I agree with you on trying Swiss, it is worth a shot (no pun intended...)

~Mako

 

[arcticap]

There's also something about the moisture content of Swiss which is suppose to impart a moister burn.
The increased polishing of the individual grains of powder is suppose to be more desirable too.
The Alder branches are suppose to be better when they're picked at a younger age and are more tender, and then processed into charcoal while they're fresher. And it needs to be debarked to make for a cleaner charcoal.
Maybe it's even hand picked by a family cottage industry?

 

[Cop Bob]

I'm Impressed... nobody can say that BP won't preform.... Nice set up BTW...

I wouldn't want to be in front of ANY of them....