30-40 Krag, RETUMBO, and QuickLoad

M

mehavey

New member
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 SAECO 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:

Krag_SAECO-301_RETUMBO.jpg

(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:

Krag_SAECO-301_RETUMBO-result.jpg

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

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

.
 
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Very nice.
But, I must ask:
Why not try the Accurate 3100?
Good fill. Good velocity. The best burn percentage in the chart. And a lower powder charge, to boot.

I like Accurate 3100 in every application that I've tried it. To me, that would have been the go-to, with those parameters and QL's results.
 
I did try it, Franken (`cause it did look good on paper)
I'll post the result tomorrow... but it just wouldn't dance.:mad::confused:

By all accounts of the Krag & cast, it really likes compressed charges of reeeally slow burners that you'd ordinarily think have detrimental burn efficiency -- WC872 is the classic. If I could get H870 anymore I'd try that too.
 
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I would love to see a Pressure Trace on it. Sure seems to shoot a treat!


Mehavey,

QuickLOAD's distributor, who controls the copyright here, gave permission for modest posting of the program's output directly on the fourm. I have a sticky post up on it here.
 
Moderators,

Any reason you can figure out as to why this image disappeared itself from Post#1 in this string ?

Krag_SAECO-301_RETUMBO-result.jpg


Cheers,
/M
 
Looks like postimage.org dropped postimg.org so redirects to postimage.org no longer work. You original URL is still in the first post. It is:

https://s7.postimg.org/dhzriuovf/Krag_SAECO-301_RETUMBO-result.jpg

Your current copy has a URL of:
https://s33.postimg.cc/xjwwqlb0v/Krag_SAECO-301_RETUMBO-result.jpg

Entering postimg.cc into the browser immediately redirects to postimage.org
Entering postimg.org into the browser gets me a 'no-such-site' message.
 
I can edit the old posts, putting the new URL into the OP. Otherwise, I will leave this as-is for others to see this sort of thing can happen and that when it does there is no clue for the reader that an image was ever in the post unless the author mentions it. It makes a good argument for introducing each image with a line like:

Image of aforementioned target:​

But the other thing you can do, which I took to doing after the Photobucket debacle, is to use the Advanced composition window, scroll down to manage attachments and upload the image to be hosted here. You can still display it in the post by right-clicking the uploaded file and copying its location and then clicking on the photo icon and pasting that URL in. Images hosted here will remain in place regardless of what Photobucket or Imagur or Postimage or other photo file host sites do in the future. Another problem I've observed on another forum is that an upgrade to a new server and a different version of vBulletin screwed everything up by munging a lot of text, including URL text. In particular, certain common punctuation marks, like apostrophes, were turned into multiple non-alphanumeric character strings three or four characters long. Very odd. Newly entered apostrophes had no problem, so this was some issue with parsing old data.
 
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