Henry rifling and PP bullets

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martinibelgian
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Joined: Thu Oct 26, 2006 1:20 pm

Henry rifling and PP bullets

Post by martinibelgian »

Yesterday we had some snow at the range(about 4 inches) while I was shooting my Steyr-Martini military rifle chambered in no.2 Musket (also known as 500/450 no.2)
The cartridge was loaded with 78 grs of Swiss 1 1/2 FG, overpowder wad, grease cookie, underbullet wad and a 510gr. roundnose bullet patched to essentially groove diameter (.458): These military rifles have a pretty long, tapered throat that wil accomodate a groove-dia. bullet seated well out.

So if you're curious how a RN PP bullet looks like after being shot in a 7-groove Henry-rifled barrel, here you go... As luck would have it; the bullet was recovered nearly intact except for some minor nose damage:
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Bullet alloy was 30:1, bullet diameter .451, patched up to .458. Shooting was blowtubing only, no cleaning between shots.
martinibelgian
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Joined: Thu Oct 26, 2006 1:20 pm

Re: Henry rifling and PP bullets

Post by martinibelgian »

FWIW, look at the base of the bullet - not even a trace of finning. Just looking at the bullet, it looks like how a PP bullets should ideally be after exiting the muzzle. Rifling is also up to where the patch ended.
Is it because the odd no. of grooves, as the Brits claim, where each land is opposite a groove in order to allow for lead displacement? Or the long, gradual throat?
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desert deuce
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Re: Henry rifling and PP bullets

Post by desert deuce »

Very interesting MB. (Looking at the base of the bullet. Not even a trace of finning. Is it because the odd number of grooves where each land is opposite a groove in order to allow for lead displacement, or the long, gradual throat?) Great questions.

If anything about long range accuracy with the black powder target rifle can be improved by experiment this set of questions certainly qualifies in my mind for further inquiry. Is anyone aware of a scientific inquiry that puts these questions to rest? Maybe recovering a grease groove bullet from the same rifle could be a start?

However, the questions concerning depth of rifling, thickness of patch, patched to bore, patched to groove, etc may also enter into the equation in this example.

Apparently, the issue of finning at the base seems to be a lingering question accepting the theory that the base essentially steers the bullet in flight.

Obviously, the move away from commercially available black powder target rifle ammunition and sporting ammunition that is paper patched happened in the late 19th century and the reason for which may be many faceted.

The Ideal Manufacturing Company, forerunner of Lyman, produced early bevel-based grease groove bullets in that time frame in 38 & 45 caliber, that I have seen, and the question of why is somewhat unclear. Was it to reduce finning or to facilitate starting the bullet into the case mouth without disturbing the concentricity of the base? The original Ideal/Lyman Postel bullet, 456132, has a creedmoor/elliptical ogive and beveled base and the current Postel Bullet from Lyman, 457132, does not resemble the original at all and there is no bevel to the base.

Were these decisions based on mass production expediency or other factors? Certainly, mass production costs per round would be higher for hand wrapped paper patched bullets than mass produced grease groove bullets. What was the transition really about?

Intuitively, the presumption was probably somewhat evolutionary, and the advertising was aimed at assuring the end user/consumer that former problems had been alleviated such as hunters with wet paper patches, non-mercuric primers, Kleenbore priming, etc, etc, ad infinitum. Today one has to wonder at the "plethora" of bullet moulds, bullet lubricants, etc available to the BPCR shooter for the purpose of improving results at competition at whatever level the shooter is engaged in?

And then that lingering mental cobweb of the mind creeps in asking the age-old question, "is the rifle and ammunition capable of a higher level of accuracy than the rifleman is capable of achieving?" Or is that a question in this line of inquiry the masses would rather ignore? :roll:
Sometimes you get the chicken, and sometimes you get the feathers!
martinibelgian
Posts: 1609
Joined: Thu Oct 26, 2006 1:20 pm

Re: Henry rifling and PP bullets

Post by martinibelgian »

Yes, Henry rifling can be considered deep rifling, which was actually abandoned after Metford introduced 'shallow' rifling.
Also, a military chamber doesn't have a 45-degree transition, actually none at all - just that taper. Which also makes it quite forgiving re. case length and bullet seating depth. Not to mention fouling.
Then, of course, this is a military rifle.
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