Another Rookie Question

[long colt lawrence]

Howdy Gents,

Thanks for the responses on the '92 blowback question. I've upped the grains to 8.6 and still get some blowback but now I know its just a matter of finding the right load, bullet and crimp ( all within the books numbers of course).
 Now I've got another issue. Here's the lowdown:

45-70 italian sharpes, 405gr rn., 31 grains IMR 3031. The book calls for 36 gr.@1400 fps and I thought I'd load it down a little. It also says the finished cartridge should be 2.550" and mine were 2.480". I'm using the lee classic loader (you know, that little tool that you need to use with a mallet). The bullet tumbles, anybody know why?   I've shot 70gr (volume) with pyrodex and get pretty good groups with no tumbling. I run a brush through the barrel every 3 shots.

Any insight would be appreciated.

I was under the impression that reloading was pretty cookbook. Its turning out to be quite a science, with alot of trial and error.

Thanks

[Mikey]

Long Colt - again, your loads might be too light to stabalize that boolet.  The 405 grain in 45-70 is a fairly long - it's a great load for the bore but if you don't power it out there fast enough you might be having the same problems you had with your '92.

I'm not certain about the velocity of the black powder loads but 70 grains of BP might get your 405 grain bullet into the velocity range where the bullet is stabalized in flight and groups well for you.  If you are using 5 full grains less of smokless 3031 you might not be getting the speed necessary for stability and accuracy.

This is one I would throw out to the black powder shooters to see what they have to say about it.  Hope this helps.  Mikey.

[jhm]

Long colt :  I am going to guess mind you now this is only a guess but I think you are getting more vel with the pyrodex than you are getting with the IMR-3031 and thats the reason you are stabalizing the bullet, you might try increasing the load gradually and see what happens, somewhere around here I had a chart that told what the vel was with black / pyrodex but cant locate it right now but someone who shoots alot more of the big calibers than I do will be in and about and we can solve this one.    JIM

[long colt lawrence]

Thanks guys......yea, the pyrodex load is hotter than the smokeless. I reckon I need to quit being so timid about my loads  but still keepem' with the books specs.

[Lee D.]

The loading manuals give a starting load.  My understanding is that you should not go much below that because a much debated thing called "detonation".  There is some theory that too light a load can lead to an actual explosion rather than a burn with smokeless powder causing catastrophic failure.  The starting loads are a safeplace to start and work carefully from there.  I generally don't load very hot because I find my guns work fine and my brass lasts a lot longer with moderate loads. that is I load my .308 to 300 savage specs. and still kill deer and bear very smartly.

[John Traveler]

Long Colt Lawrencem,

That 31.0 grains of IMR 3031 is much too light for the 405 grain lead bullet you are using.

I've standardized on 36.0 - 37.0 grains of IMR 3031 with 405 grain lead bullets to duplicate the old US Military load velocities.  Accuracy is very good out of my M1873 "Trapdoor" Springfields, M1895 Marlin, and Remington Rolling Block rifles.

Just a grain or so below that level, and I get unburned powder granules in the action, sooty cases, and poor accuracy....all signs of incomplete combustion.

Try increasing your loads in 0.5 grain increments, starting at 35.0 IMR 3031 and Federal Magnum Rifle primers.

HTH
John

[Iowegan]

Factory Black powder loads for the 45-70 were 1880 fps for a 300 grain cast lead bullet and 1330 fps for a cast lead 405 grain bullet.
Make sure you are using .458 diameter bullets. The 45-70 requires a sturdy crimp to insure good ignition.

[The Shrink]

First, what is the composition of the bullet?  A hard cast bullet or a jacketed bullet won't bump up to fill the bore, and this can cause the tumbling.  If you're buying lead bullets they are most likely hard cast, and if you're using jacketed they should fit the bore.  Your bore should be .458 and the jacketed bullets made to fit, but I'd check that relationship first.  

I don't shoot smokeless in the 45-70, so can't comment on the load, but I agree that the velocity sounds low, and that can cause tumbling if the bullet isn't stabilized.  

by the way, the heavy crimp issue is with the 405 gr bullet or smaller and BP.  The issue is that the bullet isn't heavy enough to allow complete ignition of the powder before it leaves the cartridge.  The 500 gr. lead bullet does not require this heavy crimp with BP.   I doubt that this will be an issue with 3031.

[Arrroman]

I like shells to have a pretty full appearance powderwise before I seat a bullet. I once loaded some .458 WINMAG to the reduced specifications from the Hornady book and lodged the bullet in the barrel on the second shot. Detonation is a scarey thing, don't go there! I got a dozen loading manuals to look through to get an idea where to go with each powder. I generally stick to the middle of the charts now. My own 45-70 load is 60grains of IMR4895 with a 300grain jacketed bullet, its a pretty full case of powder with very little shake and it shoots MOA. Good luck hunting!