Hello all - My buddy and I loaded some 45-70 rounds using IMR-4064 power - his loads were a tad less than 1,000 fps, his with 28 grains of 4064 with a Lee .457-340 (weighted about 345 grains) bullet while I used 30 grains of 4064 with a Lee .457-405 that cast around 415 grains a tad over 1,000 fps on chrono. He shot his from a H&R with 22" barrel, while I used an old Springfield trapdoor with a 22" barrel (been cut down before I got rifle).

He reported his powder didn't burn clean at all - said after firing he would even pour a few grains from fired brass. I didn't see anything to make me think my rounds were not burning clean - I didn't really check, but nothing flagged attention. He was with his Dad shooting at home while I was here at my home shooting.

Now, my question - could the unburned powder be caused due to lower chamber pressure? Per QuickLoad the 345 grain bullet with 28 grain of 4064 power has about 6050 PSI of chamber pressure while the 415 grain bullet should have around 7850 psi. After all, 4064 is a fairly slow burning power - perhaps 3031 would be a better choice for lighter loads? Too bad there is no longer much data for the IMR 4759 powder, I've got 3 lb of it  I'd LOVE to find a QuickLoad powder file that had IMR 4759 powder.

Thanks to all for any info.

Ken H>

Thank you for your comment - I've never used 4064 powder before, just happened to have half pound can from my brother (or was it BIL?) and was using it up mostly just to get rid of it.  I've used more 3031 over the years in a 30-30, or a slower powder in a 25-06 loaded heavy so there was no danger of unburnt powder.

I'd been reading several folks lament that 4759 was no longer made because it was so good for BPCR loading, so when I went by local gun store and they had 3 lb on the shelf I got all 3 lb.  While it might be really good powder, not sure but what it might have been better to have got a current powder so as I developed a good load, I wouldn't be running out of that powder anytime soon {g}

Ken H>

Thanks - I'd not considered that a large volume case needed the faster burning powder - does the straight wall make a difference over bottle shaped case?

Yep, I'm learning that QL does a GREAT job - doing a bit of research this morning I found that H4227 is the same burn speed as 4759, so using that data gives very reasonable data for 30-30 and 45-70 both.

Oh, the buddy either has already shot up the few we loaded, or we'll just pull the bullets and start over.

Thanks to all for confirming my thinking.

Ken H>

Many people find a accurate load somewhere between 24 - 28 gr of 4759, using 400+ gr bullets. If you have them or can get them, use either Rem 2 1/2 or F150 primers, it will make a difference with 4759.

Frank

The reason is that I always got better accuracy with the pistol primers and 4759. I like Rem 2 1/2 best for it. They are the weakest primers, that I know of. 4759 is a only uncoated powder, that I know of in the powder range that we use and is easy to ignite because of that but, you still need enough pressure to to get it to burn clean.

I've used it in 30/40, 32/35, 32/40 and 45/70 in straight smokeless and duplex BP (GOEX). Besides the best accuracy, I also got the best chrono results with R 2 1/2 and F150.

In the end, only your rifle can tell you. Buy a box of R 2 1/2 and do a side by side test with your best load of 4759. A couple of 10 shot groups, of each, should show if they work.

That said, 4759 has never gave the best OA accuracy, accept with duplex, in the under 45/70 loads. I got the best duplex 45/70 with 296 powder.

Frank

When you ran the Quickload what did it say was the % of powder burned?  My all time favorite powder when I was shooting 45-70 was 4759 but because at times it was hard to get I tried others and found IMR 4198 and 3031 gave good results as well.  Most of my shooting was with duplex loads using 7 grains of 4759.  I never tried 4227 but it is giving me good results in a 38-55.  Tom

SR4759, 5744 and 4227 are about the same burning rate so you can use starting loads from all 3 to find a load that works.

Depending on the strength of your rifle and the weight of bullet used you can start at about 22 to 23 grains. You will get a few unburned grains in shorter barrels. 

Some data is available in the Lyman cast bullet handbook and in the old Accurate Arms (1994) manual (5744) 

See page 53 for Trapdoor data for 5744
Page 54 has higher pressure data not recommended for trapdoors
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I've had really good results accuracy wise with AA5744 in 45-70 using 510 grain round nose bullets. I used the starting loads for trapdoors posted on Accurate's site. 

It is a dirty powder however, and takes several passes of the wet and dry patches to get the bore clean. Conversely, 55 grains of 1 ½ F Olde Eynsford was an easy clean up with very loose fouling, and it shot well too.