The magnum advantage: about 10%

[runtohunt]

popspastime,

Make certain your Shooting Chrony is fully opened; otherwise, it will give you a false reading of excessive velocities.

Been there! Done that!

 

[popspastime]

Wow - what are you using for a barrel?

That's almost 300 fps faster than the fastest load in Nosler's newest manual.

They're showing 3432 fps from a 26" 1-9 twist Lilja, for the 140 gr bullets pushed by a max charge of RL-25.

Guy

I'll have to look up the lit but it's 79.5 of RL22 thru a 26" Doug Sup air gauge 1 - 9 barrel with the proper free bore.. I'd have to measure that if you needed the info.
Also about the reloading manuals.. I don't know what's going on with them all but the stats are different from book to book. I'll generally look at all the different specs on a recipe before getting started and they seem to be all over the board with the same quantities and bullet weights.
Not until lately has there even been any good starter recipe's for that caliber. My choice was the RL 22 and started at 78 grains. With that I loaded 2 rounds of each 1/10th higher up to 81 grains. At 80 grains the primers started to show some pressure so I backed the load to 79.5 and went on from there. Don't forget, back when it was developed there was nothing on reloading other then what each other tried, strictly trial and error.

pops

 

[DrMike]

79.5 grains of RL22 pushing a 140 grain AB should generate a velocity of ~3332 fps.

 

[popspastime]

79.5 grains of RL22 pushing a 140 grain AB should generate a velocity of ~3332 fps.

You are looking at a nosler book to get that and is not correct. Exactly what I'm talking about..Nosler No. 3 Book states in the 7 Rem Mag, that 67.5 grains of RL 22 pushing a 140 gets out at 3340 thru a 23.5" barrel..???? Now I ask you.. are these 2 calibers even in the same ballpark or do you think the published info is a bit off??

 

[DrMike]

Actually, I applied QuickLoad to generate that velocity. Did you measure the velocity with a calibrated chronograph? Are you confident in your numbers? What were the conditions of your test? What is your loading data? Without this information, the numbers you are throwing out are gibberish.

 

[SJB358]

Yeah, I am with Mike. Something is amiss. Not saying it isn't possible, but you would need one LONG barrel to get those sorta speeds with RL22 and 140.

Cartridge : 7 mm STW
Bullet : .284, 140, Nosler AccuBond 59992
Useable Case Capaci: 89.350 grain H2O = 5.801 cm³
Cartridge O.A.L. L6: 3.650 inch = 92.71 mm
Barrel Length : 26.0 inch = 660.4 mm
Powder : Alliant Reloder-22

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 76 63.20 2680 2233 33574 11100 94.4 1.605
-18.0 78 64.78 2745 2343 35875 11411 95.5 1.565
-16.0 80 66.36 2810 2455 38316 11704 96.5 1.520
-14.0 82 67.94 2875 2569 40909 11978 97.4 1.474
-12.0 84 69.52 2939 2685 43664 12232 98.1 1.429
-10.0 85 71.10 3003 2803 46591 12464 98.8 1.386
-08.0 87 72.68 3066 2923 49700 12672 99.3 1.345
-06.0 89 74.26 3129 3043 53003 12857 99.6 1.305
-04.0 91 75.84 3191 3165 56512 13015 99.9 1.267
-02.0 93 77.42 3252 3288 60241 13147 100.0 1.231 ! Near Maximum !
+00.0 95 79.00 3313 3412 64206 13257 100.0 1.196 ! Near Maximum !
+02.0 97 80.58 3373 3536 68424 13361 100.0 1.162 !DANGEROUS LOAD-DO NOT USE!
+04.0 99 82.16 3432 3661 72912 13462 100.0 1.129 !DANGEROUS LOAD-DO NOT USE!
+06.0 101 83.74 3490 3787 77691 13559 100.0 1.098 !DANGEROUS LOAD-DO NOT USE!
+08.0 102 85.32 3548 3913 82784 13653 100.0 1.068 !DANGEROUS LOAD-DO NOT USE!
+10.0 104 86.90 3605 4041 88216 13742 100.0 1.038 !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 95 79.00 3436 3670 76310 12820 100.0 1.108 !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba 95 79.00 3129 3045 52148 13442 97.7 1.312

 

[FOTIS]

140 Grain Nosler AccuBond's being pushed at 3700 fps. out of a 7MM STW is enough for me never to look back at the standards again.

That is a lot of speed. Mine maxed out at 3500 fps with 7828.

There is no such thing as a free lunch

 

[Rigbymauser]

A .270wea will max about @ 3350ft/sec with a 140grain bullet.

 

[usmc 89]

The bullet impact will tell you exactly how fast your really going. Zero at 100, fire at 500 or better and see what the come up ends up being IE mils or moa. Run your numbers through a ballistic program and adjust your velocity until it is conducive to the applied come up. chronoraphs lie, bullet impacts dont. Not saying your stw isnt going that fast, just saying 3700 is a big number in the 7mm regardless of bullet weight.

 

[Antelope_Sniper]

I shoot alot of STW, no way 3700 with 140gr bullet and RL22 is correct.

You might be able to get close with a case full of WC860 and a 30" barrel, but you would need a slow powder with a long barrel to get anywhere close to that with acceptable pressure levels.