ERROR IN LYMAN 50th RELOADING MANUAL FOR KRAG

[Skirmisher]

Note also that the Hogdon website for IMR4895 and 180g bullet shows a max load of 35.5 but no starting load is listed.

[Parashooter]

. . . Maybe Parashooter could run quick load on the offending Lyman recommendation. . .

Doesn't look real bad. Note pressure estimates are CIP piezo (PMAX 47137psi).

[tt]Cartridge : .30-40 Krag
Bullet : .308, 180, Hornady RN 3075
Cartridge O.A.L. L6: 3.089 inch or 78.46 mm
Barrel Length : 30.0 inch or 762.0 mm
Powder : IMR 4895

Predicted data by increasing and decreasing the given charge,
incremented in steps of 1.25% 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

-05.0 84 38.00 2450 2399 36939 5329 99.1 1.635
-03.8 85 38.50 2477 2453 38212 5380 99.3 1.612
-02.5 86 39.00 2505 2508 39529 5428 99.5 1.587
-01.3 88 39.50 2532 2562 40890 5473 99.7 1.563 ! Near Maximum !
+00.0 89 40.00 2559 2618 42296 5515 99.8 1.540 ! Near Maximum !
+01.3 90 40.50 2586 2673 43751 5554 99.9 1.518 ! Near Maximum !
+02.5 91 41.00 2613 2728 45254 5590 100.0 1.496 ! Near Maximum !
+03.8 92 41.50 2639 2784 46810 5622 100.0 1.474 ! Near Maximum !
+05.0 93 42.00 2666 2840 48418 5652 100.0 1.453 !DANGEROUS LOAD-DO NOT USE![/tt]

[Dusty31]

Thanks for posting this.

I haven't used that manual for 180 gr data, but I have notes from 2018 having loaded 220 gr Hornady 3090's with Lyman's starting load of 35.0, Win primers, bullets seated to just cover the crimp groove. I noted vertical stringing at 50 yards but no other signs of pressure issues. I did not chrono those.

[RicKrager]

I just checked my old stand-by, the Lyman 45th Edition, and found IMR 4895 listed with a range of 38.0gr starting, to a max of 42.0gr. Checking another source with Hornady data for the 180 grain bullet the powder grain range was 38.0 to 42.0 for H4895. There has been discussion elsewhere regarding the difference between H4895 and IMR 4895. They are not the same thing, as I understand it. It could have been a typo when adding the listing to the Lyman book from way back. Nice to compare notes - it makes us safer. Thanks

[KWK]

Hodgdon website lists a max of 35.5gr for a 180gr bullet.

That "Hodgdon" data is old DuPont data they inherited when they took over IMR. I don't understand why DuPont had trouble with 4895 in their tests, but it placed low for both bullet weights they published. Note that for the 180 gr bullet DuPont used, the max charge of 4064 is 41 gr, which compares favorably with Lyman's 42 gr for that weight Speer bullet. Both tests gave about the same speed, too. 4895 and 4064 generally aren't that different, so Lyman's data is no surprise. I've read 4895 is actually better than 4064 when pressures aren't way up there.

Look closer at the "Hodgdon" data for the 180 gr bullet. 35.5 for 4895 but 38.0 for 3031? The 4320 data is consistent with the 4895, though.

Beats me what's up, but I'll note the chronograph data isn't consistent. Lyman's starting load of 38.0 gave 2172, but 35.5 at Hodgdon gave 2270 fps (in a slightly longer barrel). Surely this can't be the same powder? It's why I depend on a chronograph when developing loads.

Next, look over the 180 gr loads at Hodgdon for the .308 Win, a cartridge quite similar to the Krag. Here, they were using piezo sensors, and 4320, 4064, and 4895 all gave about the same pressure and fps for about the same charge weight, even for the starting loads which are getting down into the Krag pressure range.

Finally, I'll point you to the 180 gr loads in the .303 British at Hodgdon. This appears to be old DuPont data, and it was shot with piezo. Here 4064 and 4895 produce the same pressure for the same velocity, both requiring 41 gr to get about 2400 fps, just about what Lyman found. What do you know, this is also about the same as those starting loads for the .308 Win.

I think the Lyman Krag data is correct.