Most of the paper patching of bullet articles I have read seem to indicate that the bullet should be of bore diam, rather than groove dia.

Attached is a picture of 12 bullet heads from a .577/450 Martini Henry Rifle cartridge. These were recently recovered from a Victorian Military Rifle Range. Even after lying in the dirt and suffering from a certain amount of oxidation for at least 100 years, these still clearly show rifling grooves. 

It's hard to believe that these grooves could have been made by the paper patch being impressed into these bullets. It can't be from the result of 'bumping up' either, as the grooves are the full length of the parallel sides of the bullets, rather than just near the base of the bullets.

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Any comments anyone?

Harry

Harry, Check your email, I sent you some material on the subject.

MP

In "The Bullets Flight " by Dr.Mann he describes a test on page 81 where he shortened a barrel to 10" to see if the Bullet was still expanding or Bumping up. He found that the Bullet had expanded .007 over Groove size after leaving the Barrel. This indicated the bullet was still in the process of Bumping up when it exited the barrel. He also did another test with an 11" barrel and did not get this effect. So we can believe that the bullet will be Bumping up for at least 10" of travel. I have shot Bore size bullets in a .45 X 2 7/8" Sharps with fine accuracy out to 1000 yds. They were cast 30/1 lead/tin and were driven by 10 Grs 4759 duplexed behind 100 Grs of Elephant Fg Black. I also have some original Paper patch bullets in .40 and .45 caliber from Sharps and they are definitely Bore size, not loose mind you, but a nice snug easy push fit. Also have some Winchester original .38-55 Paper patch bullets and they also are a nice snug push fit in original Winchester 
38-55 bores. HTH, Regards, FITZ.

Gentlemen,

Many thanks for your replies.

Michael, thanks for  the article, it was very interesting.

Brent, It's 30 years since I last owned a British Service Martini Henry and I've long ago lost note of the internal barrel dimensions I made at the time. It did have quite deep Henry rifling and it always shot better with patched bullets. I never had much opportunity to shoot it over 300 yards. I wish I hadn't sold it, today it would be worth a fortune, I paid £20 pounds for it, sold it for £50, today it would cost me £1,000 to buy one in similar condition. It was in almost 'mint' as the collectors say.

Gert, your bullet design looks very interesting, I'd like to see the resulting targets when it's operational. If it works, I may order a mould through you.

Harry

Harry,

just don't hold your breath - after all, the rifle still needs rebarreling, so....   But I don't mind sharing the design specs with you - I actually had the mould made by Mike Neumann in SA, but just about anyone of the custom mould makers should be able to turn out one of these with the right specs.

Gert

Why Harry,
There is always the running deer competition for a sporter...  after all, if it's an incentive, I'm the current trophy holder in the vintage rifle category at the Imperial  .

Harry,
Now I am green with envy...   My longest rifle range is 78 meters, and I am on the waiting list for the only club in Belgium that has a range out to 400 meters.  For the rest, I come over to Bisley for the Imperial, the Trafalgar whenever I can and also the HBSA LR matches, just to have the opportunity to shoot at Stickledown...  It is the only time I am able to shoot really long range!  But at least I can stat that I have had the pricilege of shooting a BP rifle at Stickledown...