| Rockdoc |
| (.400 member) |
| 23/05/16 09:10 AM |
Re: Black powder to Nitro
|
Quote:
Thanks, but assuming the rifle and design are not strong enough for nitro, will a new set of barrels alone make it strong enough? (Of course I realize the cost of new barrels will easily be $15k plus). Is the depth of the rifling significant pressure wise? I know the weight is important and nitro barrels are significantly heavier.
I'm struggling to get at the fundamental question, because I don't know what it is.
The rifle I am thinking of is something like one of the Fraser hammerless doubles from around 1880.
I would take the rifle to a recognize gunmaker and get their opinion.
Many changes occurred to double rifle design with the transition from low-pressure black powder to nitro. I have read reports of frames cracking and going off the face with early NE rifles.
Hence, internal changes that are not externally obvious (locking arrangements, load-bearing surface areas etc.) and eventually bolstered frames.
I think that barrels may be part of the answer, but not the whole. Compare the pressures reported for black powder versus nitro:
450-3 1/4" BP 11-12tpsi
450-3 1/4" NE 16-17tpsi.
However, tropical loads, as favored by early NE H&H double rifles are proofed for lower pressure, e.g. My 500/450 3 1/4" is proofed for 12tpsi. That they can take higher is proved by their chambering of at least one full powered 450 No.2 cartridge in 1905 (13.7tpsi). Tropical loads seemed to be on the wane post WW1? Tropical loads are lsited by Kynoch in their 1902-03 catalogue, but they are not listed by Eley Brothers in 1910-11.
Perhaps it is possible to get new barrels chambered for a Tropical load or a low pressure load. Again, this is a question for an expert with the particular rifle in hand.
Hope this helps.