| casper50 |
| (.400 member) |
| 17/05/24 07:26 PM |
.577 BPE needs the 640 grain
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I have 10 640 grain 580 diameter bullets that I loaded a couple of today. With the same powder load they shot 6" closer to center than the 535's that I used last week. So I'm looking for some heavier 640ish grain bullets. I've found two molds at Buffalo Arms that cast a 640 grain .580" and a 645 grain .585" hollow base minie bullet. With my problem of no crimp with the .580" last week I'd like to try some of the .585's. Don't want to buy the mold until I know they work though. So I'm looking for some .585" bullets. Seem hard to find.
| LTK |
| (.224 member) |
| 17/05/24 11:29 PM |
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Re: .577 BPE needs the 640 grain
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Before purchasing a mould, plug your data into this twist rate calculator on "Berger bullets" sight to confirm stability. When I bought my .500 BPE last year it came with a box of loaded ammo than had 440GR woodleigh bullets. I had no intention of shooting someone else handloads so I pulled the bullets and dumped the powder and reloaded them with a load that I KNOW what is in there. My research showed that Alex Henry .500 were intended to shoot 300-340GR bullets. I checked the rate of twist and found it to be 1-38", much too slow for a 440 gr bullet. I bought a mould from NOE that throws a 325GR slick bullet (@ 20-1 lead/tin) and according to the Berger bullet calculator, my rifle should provide great stability for that bullet. My preliminary tests suggest this to be so as, at a particular powder charge it put 5 out of 6 shots in one large but ragged hole @ 50 yards.
| casper50 |
| (.400 member) |
| 18/05/24 12:37 AM |
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Re: .577 BPE needs the 640 grain
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The data for the mold does not give a BC.
| 85lc |
| (.375 member) |
| 18/05/24 03:06 AM |
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Re: .577 BPE needs the 640 grain
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LTK is exactly correct. However, Casper has already checked that his rifle stabilizes the 640 gr bullet, at least at the ranges he is shooting.
I guess you could put a bullet into a vice and squeeze it slightly so the diameter is 0585" and try it for loading and seating in his rifle.
| casper50 |
| (.400 member) |
| 18/05/24 03:52 AM |
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Re: .577 BPE needs the 640 grain
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The twist rate of the .577 is around 1 in 96". A very small amount over 1/4 turn in 24". The heavier bullet that I have is a 615 grain, .584" diameter and is 1" long. Sound about right so far?
| LTK |
| (.224 member) |
| 18/05/24 04:44 AM |
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Re: .577 BPE needs the 640 grain
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Quote:
The data for the mold does not give a BC.
I did not add the BC, just bullet length, weight, calibre, rate of twist and muzzle velocity. It still gave the results even without the BC.
| DarylS |
| (.700 member) |
| 19/05/24 12:08 AM |
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Re: .577 BPE needs the 640 grain
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Interesting Casper's.577 shoots such a heavy bullet while having a round ball rate of twist. Annomolies do exist.
Even the best .58's, the Enfield .577 ML's shot best with a 48" twist. The 1853, 3 bander had a 78" twist. The 1858 and 1863 both had 58" rot's.
The 1/4 turn of rifling was Forsyth's idea for the nest rot for 16 through 14 bore rifles for round balls.
Not suggesting anything, just stating what has transpired before.
| 3DogMike |
| (.400 member) |
| 19/05/24 12:12 AM |
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Re: .577 BPE needs the 640 grain
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Thought I’d chime in.
The 1-96 twist seems awfully slow for a ~640 grain bullet. But hey, if they stabilize then it’s OK.
I have several double rifle .577 BP Express’ of various vintages , late 1860’s to late 1890’s. The ones that are known to have been intended for the heavy 650 grain bullet (1890’s) are in the vicinity of 1-32 to 1-36 or so twist, dependent on maker.
Those known to have been intended for 520 -560 grain bullets are about 1-52 to 1-56 twist
My one from ~1870 does have a 1-96 twist and it works best with a very “stubby” 450-480grain bullet.
Truly, one never knows until test firing. As well, it may make a difference whether the loads are black powder or modern Nitro for Black.
- Mike
| DarylS |
| (.700 member) |
| 19/05/24 05:14 AM |
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Re: .577 BPE needs the 640 grain
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Annomolies do exist, so use what works.
| pondoro62 |
| (.275 member) |
| 19/05/24 07:02 AM |
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Re: .577 BPE needs the 640 grain
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My Lyon & Lyon .577BPE 3" hammer is made as late as year 1900..
It is regulated for 167 grain black and 650 grain bullett