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I need a little help. I have a Tri-Star .45-70 Sharps clone that I've always shot with black powder. The manual states it is made for black powder loads and smokeless loads should not exceed BP pressures. I want to load some .405 LFP bullets with Trail Boss powder. According to Hodgden reloading data this should give me muzzle velocities of 971 to 1007 fps at 25,600 CUP. Now I know these muzzle velocities are within the BP range but I don't think I've ever seen BP pressure measurements. I'm making the assumption that this is Ok but I'd like to know what pressure ranges BP usually operates in. Any info would be informative.
 

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I'd presume traditional black powder 45-70 loads run in the 17,000 to 21,000 CUP range. A Sharps clone should be able to withstand loads to 28,000 CUP. Some of the old Springfield Trapdoors I'd worry about at that level.
 

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mcg
I have 3 45/70 rifles and haven't used black powder in them for over 30 years.
Just use the loads that are designated for Trapdoor Springfields.
Your rifle is in the same classification as them.
Frank
 

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I just checked Hogdons manuel and they list several powders for trapdoors. I only have a Contender in 45/70 but have found H322 to be a very good powder, but I almost always use polester as a buffer to keep the powder down next to the primmer, has been very accurate for me.
 

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Discussion Starter · #5 ·
Follow up

Good info, all. I had come to the same conclusion but just wanted confirmation. I looked at some modern rifle data and saw CUP from 30 to 45,000. Didn't want to get near that so I figured 25,000 max would be good.
On the filler issue. I bought some Puf-Lon for just that purpose and have read instructions to fill the case to the top and load the bullet for maximum compression - or - to load close to the top to allow for some compression. What's your method?
 

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I just use polester fibers such as your use in a pillow. You can buy it at a dept store for under $4 and will last a life time, just keep it clean. I simply tear off a small piece and push it in with the erasor end of a pencil, using a twist to get in the case and then tamp it down.

I looked into the ready made filler once but I thought what I do would be just as easy, and it works good, have good groups and seems to take deer quite well :)
 

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My standard smokeless load for weaker .45/70 rifles was 20.0 grains of 2400 with any bullet from 350-550 grains. The heavier the bullet, the heavier the recoil, but pressures were safe. I never used a filler of any kind with these loads and never felt the need for any. I fired thousands of them from about 1969 through 2006 when I got out of the .45/70 business.

You do have to be careful to avoid a double charge (I used a 50-rd. loading block and inspected all cases with a good light before seating bullets).
 

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Good info, all. I had come to the same conclusion but just wanted confirmation. I looked at some modern rifle data and saw CUP from 30 to 45,000. Didn't want to get near that so I figured 25,000 max would be good.
On the filler issue. I bought some Puf-Lon for just that purpose and have read instructions to fill the case to the top and load the bullet for maximum compression - or - to load close to the top to allow for some compression. What's your method?
None of the Hodgdon loads use a filler. Adding one will increase the pressure to some degree. I can tell you from experience that Trail Boss won't need one, and none of their loads using IMR 3031 will need one either.

BTW, if you check out some other manuals, you'll find that their "trap door" level loads are quite a bit hotter than others.

A nice shooting load in your rifle would probably be a 405gr cast bullet with 38gr to 40gr of IMR-3031 in a WW case, and a CCI 200 primer. You'll get BP velocities or maybe a bit faster (in the 1200 fps range). That load is accurate in all of my .45-70s and is milder than the Hodgdon trap door loads.

Edit: note that Trail Boss loads are mild, but since it's such a fast burning powder, pressures are not really low. According to all of my manuals, the load I listed above with IMR-3031 will run at substantially less pressure.

Chris.
 

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None of the Hodgdon loads use a filler. Adding one will increase the pressure to some degree.

Correct, but if you work up the load with filler the filler becomes part of the propellant. The idea is that the filler keeps the chage tight to the firing primer. Filler has long been used in 45/79 loads with good results. Another 45/70 loader started me on it and I feel my loads are safer with filler then without, no danger of hang fires :)
 

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There is a lot of BS about .45-70 pressures bandied about on line. Few pressure tests of .45-70 loads are published, and one of the few accessible published tests was by Mike Venturino in the February 1998 issue of Shooting Times. Using Oehier M43 strain gauges, here is what he found with factory ammo in a Shiloh Sharps M1874:

Load................Velocity.....psi
Rem 300 HP......1931....25,600
Win 300 HP.......1922....32,500
Garrett 315FN...1769....33,900

I wouldn't shoot the Winchester ammo in an antique BP design, not when the Remington has the same velocity but 25% less pressure. The same article listed BP pressures:

Load.....................Velocity....psi
530 RN - 60.0/Fg......1106..31,800
530 RN - 60.0/FFg....1123..25,400
530 RN - 62.0/CTG...1148..29,800

Now M-43 pressures are relative not absolute, but it appears that factory-level loads generate the same general pressures as BP loads. The reloading industry does not agree on what the different levels of .45-70 pressures should be, see below:

Data Source….Trapdoor…Marlin….Ruger (CUP)
Lyman…...……18,000…..28,000….40,000
Speer…….…….21,000…..28,000….35,000
Hornady……….25,000…..40,000….50,000
Hodgdon………28,000…..40,000….50,000
Factory……..…18,000 reported

Case fillers are no longer recommended for .45-70 loads. Even Lyman abandonded this practice a decade ago. The risk of ringing a chamber even with an appropriate filler is small, but it is real and it does happen. It's your chamber.


.
 

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The last time I loaded smoke less powder in the 45-70 I used one of the older Lyman manuals that had loads listed in catagories of action strength. Reloader 7 was my choice then and still is.
Look for one of those manuals or go to Loaddata.com.
Good shootin'
 

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I have been using 13.5 gr. of Unique with a filler of Dacron under a 385 gr. Lyman cast bullet for light loads in my 45-70 they shoot quite accurately out of my BC. I just bought a can of Trail Boss and will be trying that as soon as I get a chance to load some up.

For 500 grainers I use 25 grains of 5744 this load is supposed to duplicate the black powder loading. It shoots accurately and the recoil is about the same as a 20ga shotgun in my rifle.
 
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