I'm working up loads for my 7mm Mag and 150 gr Sciroccos. The Swift manual doesn't have any load data for the new powders and I've used load data from Alliant and IMR.

The powders I'm testing are IMR 4955, 7977 and RL 23 and 26.

I'm setting COL at max for my magazine - 3.34" and that still gives me >.30" to lands.

My goal is to narrow down which powder is most accurate and focus on load development from there.

Here's what some old Software says. It does not even list those powders. I tend to use 7828SSC since it will work with the heavier bullets, too. Note that these loads GUESS that they will yield 55k max pressure, so 60k loads might be 50 fps faster. As always look up the mfg load data before starting.

Please keep me posted. I've just started development for my new to me S&W1500, 9.5" twist, 24" barrel, 3.6" mag box.

Powder type Filling/Loading Ratio Charge Charge Vel. Prop.Burnt P max P muzz B_Time
% Grains Gramm fps % psi psi ms
--------------------------------- -----------------------------------------------------------------
Vihtavuori N570 106.0 75.0 4.86 3091 94.0 54570 14862 1.212 ! Near Maximum !
Hodgdon Retumbo 109.5 73.9 4.79 3079 99.9 54570 13652 1.206 ! Near Maximum !
Hodgdon H870 112.6 78.0 5.05 3075 96.0 54570 14498 1.215 ! Near Maximum !
ADI AR 2218 109.4 78.2 5.07 3071 93.3 54570 15028 1.198 ! Near Maximum !
Alliant Reloder-25 102.5 68.4 4.43 3049 100.0 54570 12871 1.212 ! Near Maximum !
Norma MRP 2 104.9 70.4 4.56 3044 98.3 54570 13660 1.226 ! Near Maximum !
Ramshot Magnum (Big Boy) 99.5 71.5 4.63 3042 98.3 54570 13461 1.210 ! Near Maximum !
PB Clermont PCL 517 99.9 71.5 4.63 3042 98.3 54570 13449 1.210 ! Near Maximum !
SNPE Vectan SP 12 99.7 71.4 4.63 3041 98.4 54570 13428 1.210 ! Near Maximum !
Norma MRP 94.8 66.4 4.30 3041 99.6 54570 13304 1.224 ! Near Maximum !
Vihtavuori N560 96.4 66.1 4.28 3033 97.3 54570 13532 1.218 ! Near Maximum !
IMR 7828 100.9 65.8 4.26 3027 97.8 54570 13169 1.206 ! Near Maximum !
IMR 7828 SSC 95.4 65.8 4.26 3027 97.8 54570 13169 1.206 ! Near Maximum !
Accurate MAGPRO 96.9 69.1 4.48 3022 95.9 54570 13601 1.226 ! Near Maximum !
ADI AR 2213 96.4 65.4 4.24 3013 97.7 54570 13024 1.203 ! Near Maximum !
Bofors RP5/NP ~approximation 96.7 65.6 4.25 3011 98.8 54570 13058 1.224 ! Near Maximum !
Raufoss RA15 96.7 65.6 4.25 3011 98.8 54570 13058 1.224 ! Near Maximum !
Alliant Reloder-22 96.7 65.6 4.25 3011 98.8 54570 13058 1.224 ! Near Maximum !

Be interesting to know more about RL-26 and 23..

I know RL-25 is reported to be outstanding in the Rem. 7 mag., and that comes as no surprise.

For starting points, there is IMR powder data for 150gr partitions and TTSX at

http://www.hodgdonreloading.com/data/rifle

I use 4451 but with ballistic tips.

A good load in a few 7 Rem Mags Ive loaded for and shot,with the 150 BT, 150 NPT, and 150 Swift SS II is 70 gr RL25 in WW brass,and fed 215 primer.

Kind of a no brainer sort of load,and velocities have ranged from 2980 to over 3100 fps depending on the barrel.

Another I used and liked is the old JOC load with 150 NPT and 69 gr of WW II H4831. The is warmish with todays powders so I would back off and work up.68 may be more like it and velocities have been around 3150 fps.

The new RL26 would be a good bet but I don't have any.