Reloading for 35/40 Krag

[Parashooter]

. . . The pressure curve you posted is in PSI not CUP. Would 51K PSI correspond with Hodgdon's 42.8K CUP? . . .

As can be seen in the chart posted below, there is no accurate way to correlate piezo-transducer (psi) and copper-crusher (CUP) pressures. There are just too many variables affecting results in different cartridges.

What I can tell you is that QuickLOAD pressure figures are calculated to correlate with CIP piezo standards, which give these "Pmax" ("MAP" in US terms) figures -

.30-40: 47137 psi
.358W: 58740 psi
.35 W: 44236 psi

If you want to use QuickLOAD to estimate loads for your .35 Krag, measure the difference in weight between an empty case and the same one filled to overflowing with water. That will yield a maximum volume from which QL will calculate usable volume for any given bullet and seating depth. Results will still be guesswork, but a bit more "educated".

Table from a 1987 Hercules data brochure, using SAAMI MAP figures -

[Parashooter]

Here's sample QL output for .358 with maximum H20 capacity adjusted to 60 grains and Pmax set at 47137 psi. PLEASE remember this is only a software estimate and may be very different from what happens in your rifle with your loads.

Cartridge : .358 Win. (@ 60.0gr H2O overflow capacity)
Bullet : .358, 250, Hornady SPRN 3525
Cartridge O.A.L. L6: 2.780 inch or 70.61 mm (seat depth 0.334")
Barrel Length : 25.6 inch or 650.2 mm
Powder : Hodgdon VARGET

Predicted data by increasing and decreasing the given charge,
incremented in steps of 1.087% of nominal charge.
CAUTION: Figures exceed maximum and minimum recommended loads !

Step Fill. Charge Vel. Energy Pmax Pmuz Prop.Burnt B_Time
% % Grains fps ft.lbs psi psi % ms

-10.9 89 41.00 2054 2341 32668 4709 91.2 1.630
-09.8 90 41.50 2077 2395 33728 4776 91.8 1.607
-08.7 91 42.00 2101 2450 34822 4842 92.3 1.585
-07.6 93 42.50 2124 2505 35953 4907 92.7 1.564
-06.5 94 43.00 2148 2560 37121 4971 93.2 1.542
-05.4 95 43.50 2171 2617 38329 5034 93.7 1.521
-04.3 96 44.00 2195 2674 39577 5095 94.1 1.500
-03.3 97 44.50 2218 2731 40867 5155 94.5 1.478 ! Near Maximum !
-02.2 98 45.00 2241 2789 42201 5214 94.9 1.458 ! Near Maximum !
-01.1 99 45.50 2265 2848 43583 5272 95.3 1.438 ! Near Maximum !
+00.0 100 46.00 2288 2907 45012 5328 95.7 1.418 ! Near Maximum !
+01.1 101 46.50 2312 2967 46490 5383 96.1 1.398 !DANGEROUS LOAD-DO NOT USE!
+02.2 102 47.00 2335 3027 48021 5436 96.4 1.379 !DANGEROUS LOAD-DO NOT USE!

[psteinmayer]

Here's a link to Michael Petrov's experiment: http://www.doublegunshop.com/forums/ubbthreads.php?ubb=showflat&Number=251923&page=2

[reincarnated]

Thanks for the link. I read all 4 pages. At least three of those who posted (Michael Petrov, "J.D. Steele", and Mark Beneson have passed on. All three are sorely missed.

[FredC]

Since it is OK to link to Double Gun this is what got me started down this road a couple of years ago:
http://www.doublegunshop.com/forums/ubbthreads.php?ubb=showflat&Number=215394&page=all
Looking through this thread I saw a reference to 35 krag loads but in recent searches I have not been able to find anything.
Parashooter,
I had already researched the PSI/CUP conversion and found it was not possible to do consistently.
On your chart with the software estimate pressures it has a 250 grain bullet and not the 220 grain I intend to use. Is that correct? If so then 45 grains of varget with a 220 grain bullet should really be in a safe territory. Even if I could get more I like the idea of a moderate charge as there will be less operator punishment and noise.
I have also given some thought to this apparent equality of the 308 30/40 at 40K cup and thought about the difference in the shoulder angle. This will become less of a difference with 35 caliber as there is a lot less shoulder remaining. I have a 308 case somewhere I will try to find it and open it up to verify.
Reincarnated,
You mentioned cracking a bolt with 41.5 grains of 4350? My son's Lyman book shows a load several grains higher at 40K from a pressure barrel. I know different guns will make different pressures with the same load, but I have a theory why some of these old Krags may be developing more bolt thrust with what should be safe loads.
On the barrel that I took off this gun the chamber was .010 oversize for some distance from the rim. Could it be the case can not swell enough at that point to grip the barrel and allows the case to stretch and slide back with too much thrust on the bolt?

[Parashooter]

. . .On your chart with the software estimate pressures it has a 250 grain bullet and not the 220 grain I intend to use. Is that correct? If so then 45 grains of varget with a 220 grain bullet should really be in a safe territory. . .
I have also given some thought to this apparent equality of the 308 30/40 at 40K cup and thought about the difference in the shoulder angle. This will become less of a difference with 35 caliber as there is a lot less shoulder remaining. . .
I have a theory why some of these old Krags may be developing more bolt thrust with what should be safe loads. On the barrel that I took off this gun the chamber was .010 oversize for some distance from the rim. Could it be the case can not swell enough at that point to grip the barrel and allows the case to stretch and slide back with too much thrust on the bolt?

1. If you want more precise estimates from QL, you have to provide the overflow water capacity, as suggested earlier. Please note that I'm just providing examples of what you could do with QuickLOAD.

2. Shoulder shape/angle has been consistently demonstrated to have negligible effect on pressure with normal loads of conventional components in cases of equal volume.

3. Chamber .010" over case body diameter is completely normal. SAAMI minimum cartridge base: .453", maximum chamber base: .464". This has no practical effect on case/chamber adhesion or "bolt thrust".

[FredC]

"1. If you want more precise estimates from QL, you have to provide the overflow water capacity, as suggested earlier. Please note that I'm just providing examples of what you could do with QuickLOAD."
How is overflow water capacity obtained? I would think it would be with the water capacity of the case with the bullet installed? I am thinking I would pop the primer and fill a case with the bullet installed using a hypodermic through the primer hole, then compare before and after weights? I have a digital scale with .0005 lb increments or a power scale that measures to .1 grain.

"2. Shoulder shape/angle has been consistently demonstrated to have negligible effect on pressure with normal loads of conventional components in cases of equal volume."
This means Roy Weatherby was a snake oil sales man? I sorta figured that

"3. Chamber .010" over case body diameter is completely normal. SAAMI minimum cartridge base: .453", maximum chamber base: .464". This has no practical effect on case/chamber adhesion or "bolt thrust"."
Learn something new everyday, thanks. Hope I can remember it all.

[Parashooter]

Posted earlier:
"If you want to use QuickLOAD to estimate loads for your .35 Krag, measure the difference in weight between an empty case and the same one filled to overflowing with water. That will yield a maximum volume from which QL will calculate usable volume for any given bullet and seating depth."

Trying to clarify the procedure -
1. Take an empty case with a spent primer in it.
2. Weigh the case on your powder scale.
3. Fill the case to overflowing with water.
4. Weigh it again.
5. Subtract the empty weight from the water-filled weight.
6. Using the density of liquid water as a constant, QuickLOAD converts its weight to volume (in cubic centimeters).
7. QuickLOAD calculates the volume occupied by the seated bullet and subtracts that from the overflow volume to yield the remaining volume.

[FredC]

Parashooter,
This is what I got on capacity of the case:
60.9 grains of water
It turns out the bullets in hand are 200 grain Sierra round nose, bullet number 2800. These bullets have a .290 inch measurement from the base to the center of the cannalure if that is needed.
I will probably use 220 grain in the future.
Is your QuickLOAD program still available and what is the learning curve like?
Thanks
FredC

[Parashooter]

QuickLOAD/QuickTARGET version 3.9 is supplied with a comprehensive "USER FRIENDLY" MANUAL included on the QuickLOAD CD-ROM disk. http://www.neconos.com/details3.htm

$152.95 plus S&H

New CD-ROM version 3.9 requires Windows XP, Vista, W-7, W-8 or W-10

http://www.neconos.com/qldemo.exe