30-40 Krag, RETUMBO, and QuickLoad

[mehavey]

Still playing with cast in the original-config 29" Krag, I've gone through multiple bullet designs/weights/velocities/powders... picky and fickle.

Finally seemed to settle a bit on a 190gr #301_SAECO 301_TC-GC in #2 using Winchester 780 Supreme ... which of course is now no longer made... And still it exhibited significant velocity swings depending on powder position in that relatively large case for the intended pressure (28ksi) velocity range.

The heck w/ it.
Ask QUICKLOAD for the best combo of
- Pressure (target 28,000 psi)
- Velocity (target 2,200 fps)
- Case Fill (103-108% to insure complete fill/slight compression)
- Burn (mid 80s and up...)

QuickLoad spits out a reeeeeeeaaaaally long list, which w/ a little filtering:


(Hopefully, this passes the Forum Terms-of-Service Test)

Problem is. there is NO published (manufacturers' or even WAG internet) data on that kind of "ridiculously unsuitable" powder/bullet/cartridge combination.

So I dig out a Berger manual which does use RETUMBO and a 190gr bullet -- for the 300 RUM. OK, what does Quickload predict for the RUM ?
Turns out it matches dead nuts on w/ Berger's data; and is reasonably consistent with interpolated Hornady and Lyman data at both MIN/MAX levels and pressure/velocities,

So we go ahead and scale it down for the Krag and take it out this evening:


(actual Oehler velocity: 2,173 ± 07 (wow)

One for the search engines then.....
(YMMV, of course. Take great care)

.

[earlmck]

Wow! QuickLoad dang near paid for itself right there. That looks like a load to go with.

[Harry O]

I have been using the standard IMR4350 ever since I started reloading the 30-40 Krag. That is a bit faster than Retumbo, but not that much faster. I am sure that it was originally chosen for the 220gr bullet, but it seems to work just as well with the 150gr bullet. I also have a wildcat based on the 30-40 Krag case. It is in a Ruger No. 3 that was originally in 30-40 Krag. It was rebarrelled and restocked for the wildcat. It is 7mm with a one-diameter neck, sharp shoulder, and the rest of the case is blown out straight. Ballistically, it is just about identical to the .280 Remington cartridge. I tried 4350, slower, and faster powders in it. The 4350 turned out best for it, too.

I have wondered from time to time what would happen if I took the slowest available rifle powder available and filled the case up to the base of the bullet, but never tried it. I guess that this answers that question.

[mehavey]

Harry, are you using IMR4350 in the Krag for cast,
or running regular jacketed at regular pressures?

[Harry O]

I have used both. Cast is with reduced loads, usually with faster powders (Lyman/Ideal 311413 is very accurate with reduced Red Dot loads). The full power loads are with jacketed bullets. Most are 150 or 155gr (usually factory seconds from Hornady, since they are common -- and cheap -- around here), but I loaded and shot some 220gr to see what it was like. They do have a bit of recoil.

[pakmc]

I'm shooting the hungrian Steyr in 8x56R with .338 bullets resized to .334 and then powder coated. I tried reddot and trail boss and they are both ok, but 16.5-17 gr's of 2400 is the sweet spot with my Hungrian steyr rifle. 1-1/2 inch groups with the first two powders(at 50 yards), but 1/2 inch groups at 50 yards with 2400(three shot groups with all bullets touching). I haven't tried this combo with my carbines yet. but the two carbines with out scopes have been shooting about a foot high at 50 yards the last time i shot them. and no, I don['t shoot factory ammo in any of them. but someone on this Fourm said 16.00 gr's of 2400 is the cats meyow for most large cases shooting lead bullets.
what else is nice about shooting lead bullets my brass doesn't try to go out the barrel, so no more(or not much) trimming the cases after shooting them.