Max bullet wt for 45-75

farrow3240 · September 01, 2009, 02:23:30 PM

Can anybody tell me what maximum bullet wt can be used in the 76's. I have a Uberti and their twist rate is 1-20. This twist rate would stabilize a 400gr or a little bigger bullet. I have tried 300 and 350 grain bullets and get mediocre accuracy. Using black powder. Tried 5744 and was not impressed. Pyrodex did ok and triple seven was pretty good. Was there a reason the original loading was 350gr bullet?

Dirty Brass · September 01, 2009, 03:26:04 PM

I think it has to do with case capacity / overall length issues. Too heavy a bullet seats too deep and negates the case capacity, or increases OAL beyond usable size. That would be my guess.

farrow3240 · September 01, 2009, 05:10:34 PM

Thanks Dirty Brass. Seems to me that Uberti would take into consideration the short bullet limitations and use a corresponding twist

. I'll keep trying and see what happens.

Hobie · September 02, 2009, 07:45:20 AM

I think you might have done some basic background on the cartridge. History tells us things...

Winchester found that in this cartridge, in this gun, with the pressures involved, the 350 gr. bullet was appropriate. Heavier bullets weren't used as it was felt they overstressed the action. Lighter bullets weren't used as they reduced the terminal performance. Remember, Winchester was trying to equal the .45-70-405 Government cartridge in a repeater. Some nominally 350 gr. bullets cast and lubed will approach 365 gr. in actual weight. This doesn't seem to be a problem.

While every gun is different, one usually finds success with properly fitted bullets which are properly lubed over appropriate powder charges. I can't be certain, but your positive results with Triple 7 and Pyrodex seem to me to imply that your bullets might be slightly undersize for your bore. I would investigate that problem. HOWEVER, Mike Venturino found that some bullets just didn't shoot well in his original despite meeting all the criteria of a "good" bullet. As I said, every gun is different...

farrow3240 · September 02, 2009, 08:42:53 AM

Thanks for the info Hobie. I was sizing to .458, but as cast shot the best so far. I'll take your advice and slug the bore and see what i am working with. I can have a custom mould made if need be. I understand what you mean about over taxing the action. Don't want to do that. I was thinking about trying IMR4198 but does not fill the case enough for my liking and I have no love or desire to use a filler as i have seen ringed barrels of other peoples firearms several times. I'm going to the NMLRA range this weekend and try some I have loaded. We'll see what happens. Thanks again.

Hobie · September 04, 2009, 02:58:01 PM

At the risk of topic drift I don't like fillers either. IMR or HH4198 fills the case over 50% which is acceptable. It is the pressures which some call into question.

farrow3240 · September 06, 2009, 09:43:00 PM

Hi Hobie, Just got back from the range. The as cast bullets did somewhat ok but still not impressed. The bore is .458 and bullets cast at .459. Surely I can get better accuracy than 3.5" at 50yds rest. I noticed that my Uberti 73 seems to like .426 and .427 bullets better than .429, which is what the bore is, so i might try a little smaller dia in the 76. The bore in the 76 is as slick as a whistle and crown looks good also, so back to the drawing board. But working up the load is part of the fun. That big 76 sure attracts a lot of attention on the line. I also have a Chap in 50-95 and am working on a load for it also. Had a mould made for it and can't wait to try it. Back to the range for more testing

john boy · October 12, 2009, 10:22:53 PM

Farrow, the most reliable way to determine what the maximum bullet weight can be for the 45-75 in a 1:20 twist is to start plugging numbers into this calculator ... Bullet Stability Calculator (MS Excel)

You can also calculate what the min/max velocity of the recipe is, to stay within a specific twist rate.

I used the calculator for the re-make of the Ideal 375166 bullet (wasn't made for close to 50 years), loaded up some rounds, went to the range and these are the groups I got:
http://shilohrifle.com/forums/viewtopic.php?t=13911

rustyrelx · October 16, 2009, 10:58:49 AM

Hello the thread. First off I do ot recommend this load....... This load was the Long Range load for the 45-75. It used a 550 grain paper patched bullet over 75 grains of 1 F powder. This load was meant to be loaded 1 at a time. It is NOT a round with repeating capabilities in the 76. Winchester had this round for the 76 in matches.
OK YOU ASKED MAX. BULLET AND HERE IT IS. Don

rustyrelx · October 17, 2009, 11:56:56 AM

Again I do not recommend this load... I want to correct previous entry..I think it was 90 grains of powder not 75, but of course anything inbetween is possible. I think this was the often times labeled 45-90 load for the 76. Single loading only.. Don

Grapeshot · October 25, 2009, 01:07:57 PM

I own one of the Chapparell .45-60's. I have used bullet weights from 300 grain cast lead to 405 grain, hollow based Government bullets over 55 grains of FFg Goex and 3Fg Pinacle. The 405 grain bullets work fine in my 1:22 inch twist barrel. The 300, 350 and 385 grain bullets also shoot good out of this gun usin 60 grains of GOEX 2Fg or it's equivalent in Pinacle. All loads are slightly compressed and are touched off with a magnum Large Rifle primer.

I found that 777 is a bit hot with the 405 grain HBRN.