Mind the gap?

[wookie76]

Greetings, all.

I'm interested in getting into BP shooting. I have some questions about non-traditional reloading if you will indulge me in a bit of internet wankery.

Does anyone have experience loading pyrodex pellets in BPCR, specifically what about the air-gap? I see a few loadings listed in the Hodgdon muzzleloader pdf. After peaking my interest I then found the following Mike Venturino article:
http://www.shootingtimes.com/ammunition/hodgdon_0728/

But he leaves me with more questions than answers.

He gives the pellet dimensions that I haven't seen elsewhere, short of actually measuring a real one in my hand.
.50 rifle - .45x.715
.44 pistol - .40x.63

Given the Hodgdon data (no dimensions on hand for the 50/30 pellet):

45-70 Gov. 405 RNFP 1 - 50/50 989 fps 14,100 CUP
45-70 Gov. 405 RNFP 1 - 50/50 1015 fps 14,200 CUP
45-70 Gov. 405 RNFP 2 - 50/30 1270 fps 27,200 CUP
45-70 Gov. 405 RNFP 2 - Pyrodex Pistol 1231 fps 21,900 CUP

With a 2.550 OAL and a .070 rim, I get
1 rifle - 1.32 void to mouth
2 pistol - .775 void to mouth
I understand these will be off since the pellet won't sit flush with the interior base.

Now, what REALLY got my thinking was that if you can have a void on the end, what about side to side? Could you then load these in a 71/84 Mauser or the bottle nosed domestics?

Thanks,
Bryce

[R.Clem]

I have never loaded pellets into a cartridge case, and truly believe it to be something to stay away from for the very reasons you mention, AIR GAP. All who shoot black powder and subs say the same thing, "air gaps cause explosive problems with black powder!"
The way I have read and understand this, air space in a case with black powder creates a hammer affect upon ignition of the powder, the pressure jumps to fill the air gap, then when the air gap has filled with burning gas the pressure is in an extreme before the bullet moves, the built up pressure has to go somewhere, as the bullet can't be driven down the bore rapidly enough to allow the pressure to drop when more of the powder is being burned than normal, (black powder doesn't burn but about 50% of the charge, that is where the fouling comes from). It has been written that one of the powder companies of old, under controlled conditioned got 100,000 psi out of a charge of black powder, we don't want anything over 28,000 psi and preferably keep it under that by 10,000 psi.
This affect is the same as a "water hammer" in a steam line, and having seen the aftermath of that, I will stick with loose powder and compressing that to get what I want.
I hope this makes sense, if you go to: http://www.bpcr.net/index-a.htm and browse technical articles, you will find a lot of information.

Ray

[Freightman]

I have never loaded pellets into a cartridge case, and truly believe it to be something to stay away from for the very reasons you mention, AIR GAP. All who shoot black powder and subs say the same thing, "air gaps cause explosive problems with black powder!"
The way I have read and understand this, air space in a case with black powder creates a hammer affect upon ignition of the powder, the pressure jumps to fill the air gap, then when the air gap has filled with burning gas the pressure is in an extreme before the bullet moves, the built up pressure has to go somewhere, as the bullet can't be driven down the bore rapidly enough to allow the pressure to drop when more of the powder is being burned than normal, (black powder doesn't burn but about 50% of the charge, that is where the fouling comes from). It has been written that one of the powder companies of old, under controlled conditioned got 100,000 psi out of a charge of black powder, we don't want anything over 28,000 psi and preferably keep it under that by 10,000 psi.
This affect is the same as a "water hammer" in a steam line, and having seen the aftermath of that, I will stick with loose powder and compressing that to get what I want.
I hope this makes sense, if you go to: http://www.bpcr.net/index-a.htm and browse technical articles, you will find a lot of information.

Ray

Glad you said that now I will not have to! and you said it much better than I could have!

[BPCR Bill]

I believe the BP substitute pellets were developed for the inline muzzleloaders. Some traditional muzzleloader riflemen may use them. I think there is absolutely no application for them in BPCR. I tried Pyrodex years ago and wasn't that fond of it from an accuracy standpoint, and it is much more corrosive than real BP. I have never entertained the idea of using these pellets in any of my BPC rifles, for many reasons. If you are interested in getting into BPCR, I urge you to consider useiing only Black Powder. Some folks may say its a PITA, but many of those with that opinion probably haven't used it to any degree to know just what they are talking about.
Venturino is a very knowledgeable man when it comes to things related to BPCR, and he can certainly take the time for product evaluation and pass on information about products that may or may not interest our little community. Heck, that's his job! I would recommend you buy the "Black Powder Cartridge Primer", co-authored by Mike and Steve Garbe. That is probably one of the best starting points for someone interested in what this game is about.
The "Explosive Force" that people are speaking of results in a phenomenon known as "Chamber Ringing".
It is theorized that if there is an air gap between the top of the powder column and the base of the boolit, this air space will compress due to a combination of explosion and powder column slamming into the boolit. Here is something to think about. In a cartridge that was developed for black powder back in the 19th century, you can ring a chamber with smokless powder as well. No kiddin'. I would refer you to "The Modern Schuetzen Rifle" by the late Charlie Dell and Wayne Schwartz. Charlie had done extensive research on chamber ringing. He tried to "Ring" chambers with black powder, and he just couldn't seem to do it. One practice that these old target riflemen did was that of "Breech-seating" a boolit in the chamber, a practice that continues today. After breech seating, a primed and charged case is placed in the chamber and the round is fired. there was of course an air gap between the boolit and the powder, and with black powder there never seemed to be a problem with ringing a chamber. It wasn't until the advent of smokeless or "Nitro" powders at the turn of the century that chamber ringing became an issue. Research at the old Springfield Armory under Col. Townsend Whelen also drew these same conclusions.
Steve Garbe and Mike Venturino also espoused the Black Powder / Air Gap = Chamber ringing theory in the Black Powder Cartridge Primer, but as recently as last year Garbe has written what may be assumed as a "retraction" on this theory in an article in the BPCR News, citing these same sources. Anyway, it's always great fodder for discussion!

Regards,
Bill

[martinibelgian]

Ah yes, the urban myth about air gap and BP... In actual fact, W.W. Greener actually advised his customers , when only a too fine powder was available, to load only a partial charge, leaving an air gap between bullet and powder. Now tell, me, why should it be possible to leave an air gap with nitro and not with BP? after all, the result upon ignition is identical... Powder ignites and generates pressure, that's what it's all about. I think springfield Arsenal once also did a series of tests with trapdoors, seating a bullet in various steps up to halfway the barrel, and then pulling the trigger on a caseful of powder. Result? Nothing special happened... No rings, no bursting, no bulges. Maybe accuracy wasn't really there, but...

[RMulhern]

[smilie=b::holysheep:groner: