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> .45/70 getting my head around pressure limits
.45/70 getting my head around pressure limits
@ 04:17 pm (GMT) |
Mike DavisOK...here goesIm in process of building a sleaved .45/70 to use in .12ga shotgun as an insert,barrel will be somewhere around 25"in total so say 23" of rifling,I realise pressure levels will have to be kept low due to action strength so arent looking to get too carried away with hot loads. reading different loading manuals it seems weird when comparing pressures between different powders the two powders I have on hand that data is there for are trailboss and 2208 trail boss loads at or just above 1000fps have way higher pressure levels than a much faster load using 2208. does this mean I should forget trailboss loads completely??? Im intending to use this as a bush hack for deer and if I can get a consistant 6" or better at 75yards will be happy (think that will be easy enough even with crude shotgun bead and groove by hammer) I have 390grn hollow base and 413grn solids both have same nose profile with 8mm flat metplate so should preform ok.....maybe 1300fps???? yes Ive read the KB 6 times...... any thoughts???? |
Replies
@ 06:47 am (GMT) |
Paul LevermanRe: .45/70 getting my head around pressure limitsSome info that may help:Always remember that the burning rate of smokeless powders is not constant. It varies dramatically based on the degree of confinement. That is why a small cartridge, such as the .22 Hornet, requires a completely different powder than a large cartridge like the .300 Weatherby Magnum. Stick with the powders recommended in the major reloading manuals for specific caliber and bullet applications. https://www.chuckhawks.com/smokeless_powder.htm At the risk of over simplifying a pretty intensive chemical process, you might think of it this way. A small pistol cartridge like the .32 ACP has low volume and operates out of a pistol with a short barrel. The powder charge has to ignite and burn quickly so the right amount of pressure can be developed before the bullet leaves the muzzle. However, in a larger cartridge like .30-06 fired from a rifle, you really want the pressure to build as the bullet moves down the barrel. If you used the fast burning powder appropriate to the .32 ACP, but in the larger quantity required for .30-06, the immediate pressure spike from a fast powder would blow up the gun. The slower burn rate allows the pressure to develop at a rate appropriate for the larger cartridge and barrel. [/url]https://www.gunsamerica.com/digest/reloading-powder-propellants-pressure/[/url] I tried to explain it but these guys do it way better. |
@ 10:44 am (GMT) |
IainRe: .45/70 getting my head around pressure limitsI'd try 2206H in that application. 2206H has a reputation for working well in less than full power loads.My only experience with 45/70 is with 2207 in strong actions with 350s, and that worked well, albeit at higher prssures than you want to use. I don't think 2208 will be as good as 2206H with the soft loads that you are planning, but if 2208 is all you have, give it a whirl. It seems as if TB isn't going to give you what you want. |
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@ 05:44 am (GMT) |
Paul LevermanRe: .45/70 getting my head around pressure limitsAre you using the existing barrel as a mount, or sleeving the whole length? If the smith does the job right, you shouldn't have to worry about your loads, as long as you don't try #1 loads. The low end Marlin loads should work just fine. |
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@ 07:28 am (GMT) |
Mike DavisRe: .45/70 getting my head around pressure limitsthe rifle barrel is being machined so it slips snuggly into shotgun barrel..full length....the fine chap who is doing work for me recently made me a .410/45lc adapter for the same shotgun and the fit is so good I have complete faith in his abilities.I decided that for now I will not muck around with extractor (Im not after dangerous game) and will pick out or poke out empty cases for a while and see how things pan out,its still going to be faster to load than a front stuffer.If after a period of time the action shoots loose it will be simple matter to slide sleave into another shotgun and carry on.tolerances are pretty good as the wee .410 sleave I have WONT fit into a Bakail .12ga barrel,would do if machined off another mm or so. |
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@ 12:57 pm (GMT) |
Paul LevermanRe: .45/70 getting my head around pressure limitsSounds like a good project. I had played with a similar idea, whereas the original barrels on a SXS shotgun were cut back and the rifled barrels were sweated/soldered into them. As it turned out, Baikal had the 45-70 in a SXS already, so I just got that instead. |
@ 09:27 am (GMT) |
Nathan FosterRe: .45/70 getting my head around pressure limitsHi Mike, take note of what Iain suggested. That is the same as I was going to suggest.At 1300fps, a hollow point is best to speed up killing. At 1200fps impact, blood trails can be less than expected if the dead run is long (versus hype of wide bores). Mid line shots can bleed to the bottom of the chest cavity rather than out of the exit wound. Therefore, a large exit wound is needed to help create a more vivid blood trail. Expansion helps. Velocity always helps so do consider a 300gr. I should have done better in the past when conveying Elmer Keith's endeavors, filled the gaps that others have neglected. Yes, Elmer was a fan of a wide meplat but he went on to create HP projectiles to gain a further increase in killing performance. Most Keith fans push the Keith style and I sometimes refer to this 'style' when writing and talking about meplats etc. But it is important to understand that Keith was not one dimensional. He understood the limitations of the flat point. Most folk neglect to take this into consideration. Keith was always pushing towards high velocities, wanting to increase performance. His bullets got tougher with increased velocity, softer or hollow pointed if he had to settle for decreased velocity. |
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@ 07:05 pm (GMT) |
Mike DavisRe: .45/70 getting my head around pressure limitsthanks for the replies chaps..... its a waiting game till she is done. Ive held off and only loaded 5 rounds so far....2 with TB and 3 just on minimum with 2208... will see how they go....now Mr Foster I blame you completely for the fact I cant get out of my head the idea to try one of the 390grn hollow based projectiles backwards....it ticks all the boxes..lovely boattail for ease of loading big metplate huge hollow point thinking it shouldnt be an issue being a break open with 1/4" freebore so no feeding issues...I know they are soft enough as one got dented in transit despite great packaging. WHEN we eventually get her up and running I will be sure to update with results....... then to find a big wallaby rear on so I get full length penertration,hopefully be able to hit bone on way in to initiate energy transpher... |
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@ 07:35 am (GMT) |
Mike DavisRe: .45/70 getting my head around pressure limitsoh and before anyone gets thier panties in a bunch.......I think the reverse idea is great and my comment re blame was tongue in cheek.still waiting.made up some 200grn HP cast loads for the .308 to pass time 10grns of trailboss should have them still subsonic,will be interesting to try them out and compare to the awesome 151grn cast hollow points I have been using from same chap. |
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