What are your thoughts on converting the 30-40 Krag to 405 Win?
They run about the same pressure and the straight case big bore should have a pressure curve that should be short. Seems a good conversion to me. It's been done before I've found out.

I'm gathering the piece-parts right now to do just exactly that conversion. COAL might be a problem but probably easily solved by seating the bullets a little deeper. I'm also considering converting to dual locking lug support.
Regards, Joe

Sounds like an intresting project, but arent 405's typically built around stronger actions?

quote:

Originally posted by Wstrnhuntr:
Sounds like an intresting project, but arent 405's typically built around stronger actions?

That's one reason I've considered converting to dual locking lugs.

My main frame of reference is the 1895 Winchester's history and rep. As originally produced it was a marginal action for the 30-40 until the frame was made wider after a few years' production. Then after the turn of the century it was chambered for the 405 and 30-1903 cartridges, and more problems surfaced. The wider frame appeared to handle the 30-40 and 405 cartridges just fine but the 30-03s and later the 30-06s developed a rep for excessive headspace just as the early narrow-frame 95s had done with the 30-40.

All this leads me to believe that a good Krag action will handle the 405 as it was originally loaded, but I gotta confess that I don't know the current pressure specs for the modern loadings.
Regards, Joe

J.D. -

You've probably already done this, but if not, you might want to....

You might want to calculate the total bolt thrust generated by the original .30-40 loadings, then calculate the bolt thrust which would be generated by some of the loads you'd like to use in YOUR Krag once it was converted to .405 Win. That should influence whether you really want to do it or not.

As I mentioned above, a fair number of Krags were reportedly blown up (had the bolts fractured according to the U.S. NRA tech service) when converted to .22 Hornet back in the 1930s-40s.

Sure, that is a higher factory pressure cartridge and was often hand-loaded hotter yet, but it also has a much smaller pressure-loaded head area on inside of the case than the .405 will have. So, I don't know how the bolt thrust forces will compare, but I'd sure want to know before I converted any of MY Krags to .405 Win.

So, if the bolt thrust on the inside of the .405 case would exceed that which you would have on the inside of an original, .30-4O load, I'd personally recommend against it.

Even if you choose to do it anyway, at least you'd have some glimpse at what margins you might be approaching.

I would think lapping the locking lug to allow both the front lug and the massive guide rib to bear would be plenty to handle the .405. The bolt handle root then still functions as a safety lug. AS for COL I think the .405 is 3.175. My old Hornady handbook lists one load for the 30-40 at 3.175" for use in the Krag so LOA may not be a problem. The head size of the .405 and Krag are the same so bolt thrust should be the same for equal pressure loads. Case length for the Krag is about 2.314" according to COW and for the .405 3.175". I doubt current loads for the .405 are loaded any hotter than the Krag as there are some ancient muskets out there that can chamber the round. If the magazine will feed the cartridge it should be a fine match.

Jerry Liles

quote:

Originally posted by Jerry Liles:
I would think lapping the locking lug to allow both the front lug and the massive guide rib to bear would be plenty to handle the .405. The bolt handle root then still functions as a safety lug. AS for COL I think the .405 is 3.175. My old Hornady handbook lists one load for the 30-40 at 3.175" for use in the Krag so LOA may not be a problem. The head size of the .405 and Krag are the same so bolt thrust should be the same for equal pressure loads. Case length for the Krag is about 2.314" according to COW and for the .405 3.175". I doubt current loads for the .405 are loaded any hotter than the Krag as there are some ancient muskets out there that can chamber the round. If the magazine will feed the cartridge it should be a fine match.

Jerry Liles

That is good info Jerry.

I'd still compare the load pressures in most current loading manuals/postings to the pressures used in original Krag ammo before I went ahead. If the modern .405 handloads he might want to use are higher pressure (and bolt thrust thereby higher), then enlightened self-interest would make it beneficial to know that.

Isn't the std pressure for the 405 less than the 30-40?

Oops. Case length for the .405 is 2.58" not 3.175". So, while case length for the .405 (2.58") is longer than the .30-40 (2.314"), cartridge overall length is about the same.

Jerry Liles