7x57 Mauser and vertical stringing

[orchemo]

I am trying to a find a load for my Win 70 7x57.

I bought a BUNCH of Deep Curl 160 gr bullets specifically for this rifle. I just want a nice shooting load, does not need to be blazing fast or 1/4 MOA, just a nice shooter.

Started with IMR-4350 and it seems to vertically string (could be me also).

Loaded some IMR-4381 tonight and will also try some RL-17.

Any other hot pics? I know I could try a different bullet, but I bought 1K of these, so I have lots to burn through first.

Cheers

 

[dubyam]

Vertical stringing sounds like a barrel float issue. Maybe check the barrel channel and see if you're getting some pressure when it heats up?

 

[Mountain Goat]

If your M70 has a 2-piece bottom metal, you might want to double check tighness of the action screws. Sometimes the front one can get too tight and "interfere" with the others. I like the rear one TIGHT, then snug the front and center.

 

[Vince]

Vertical stringing sounds like a barrel float issue. Maybe check the barrel channel and see if you're getting some pressure when it heats up?

That's what I was thinking too.

 

[RiverRider]

I think I'd try varying the powder charge up and down by about two tenths of a grain at a time. If you've got room to go up by .2 or .4, you might find the sweet spot there.

 

[Rigbymauser]

My experience with vertical groupings on the target has something to do with inconsistant velocity. Check that also. Loose screws usually just scatters the pattern.

 

[Oldtrader3]

My latest issue with vertical stringing and H-380 was from having been developing loads for my 9.3x74R, using 4064, 7828 SSC and 4350 and all three powders were showing promise for tight, round groups close to or just above MOA at 100 yards. The last powder which I had loaded for testing was a near max H-380 load just to try ball powder. The H-380 group was about 1 inch wide and 6 inches tall (5-shot group). This compared to IMR 4350 which shot a close to MOA group, 1-1/8 wide by 1 inch high 5-shot group. I gave up on the H-380.

 

[SJB358]

I would say it is something in the bedding or just doesn't like the powder at all. I know I need to shoot my boys 7x57 fairly slow, as it is a lighter weight barrel, but I have really only worked with RL19 and RL17, RL17, being really good across the board.

Cartridge : 7 x 57 mm Mauser (SAAMI)
Bullet : .284, 160, Speer DCSP 1639
Useable Case Capaci: 53.638 grain H2O = 3.483 cm³
Cartridge O.A.L. L6: 3.071 inch = 78.00 mm
Barrel Length : 22.0 inch = 558.8 mm
Powder : Alliant Reloder-17

Predicted data by increasing and decreasing the given charge,
incremented in steps of 2.0% 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

-20.0 75 38.80 2272 1834 33268 9063 96.1 1.454
-18.0 77 39.77 2325 1921 35408 9306 96.9 1.418
-16.0 79 40.74 2378 2009 37680 9534 97.7 1.381
-14.0 80 41.71 2431 2099 40094 9749 98.3 1.341
-12.0 82 42.68 2483 2191 42656 9947 98.9 1.302
-10.0 84 43.65 2535 2284 45382 10130 99.3 1.265
-08.0 86 44.62 2587 2378 48280 10295 99.6 1.229
-06.0 88 45.59 2638 2473 51364 10442 99.9 1.195
-04.0 90 46.56 2689 2569 54626 10569 100.0 1.162
-02.0 92 47.53 2740 2667 58146 10680 100.0 1.130 ! Near Maximum !
+00.0 94 48.50 2790 2765 61876 10784 100.0 1.099 ! Near Maximum !
+02.0 95 49.47 2839 2864 65855 10885 100.0 1.069 !DANGEROUS LOAD-DO NOT USE!
+04.0 97 50.44 2888 2964 70108 10984 100.0 1.040 !DANGEROUS LOAD-DO NOT USE!
+06.0 99 51.41 2937 3065 74652 11079 100.0 1.013 !DANGEROUS LOAD-DO NOT USE!
+08.0 101 52.38 2985 3167 79514 11171 100.0 0.986 !DANGEROUS LOAD-DO NOT USE!
+10.0 103 53.35 3034 3270 84727 11259 100.0 0.960 !DANGEROUS LOAD-DO NOT USE!

Results caused by ± 10% powder lot-to-lot burning rate variation using nominal charge
Data for burning rate increased by 10% relative to nominal value:
+Ba 94 48.50 2883 2952 73718 10400 100.0 1.026 !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba 94 48.50 2649 2493 51069 11045 98.2 1.194