7mm SAUM and Reloader 17

[gregsjt]

I've got a 7mm SAUM with a 8.5 twist 25" barrel. I've been doing some load development with this cartridge and the 162 Amax and have found that with Reloader 17 I'm getting about 100 fps more than with any other powder. I've tried H4350, Reloader 22, H4831SC, H1000, and IMR4831.

I'm a little worried about the temp sensitivity of this powder, have any of you used this combination for an extended period of time? Should I be concerned and keep looking for another combo, or is the temp sensitivity over rated? I'm not really worried about getting the most velocity possible, I'd rather just have a stable accurate load. Any advice or feedback is appreciated.

 

[k0pw]

Re: 7mm SAUM and Reloader 17

Unless you are loading up to within 100 fps of catastrophe, you don't need to "worry" about the shift. What you do need to do is characterize the change, so you know what to expect over a given amount of temperature change. Given the tie between hot and cold temperatures, the easiest way to do it is to load up some loads as close to one another as possible, Divide them up into two ziploc bags and chill one to the lowest temp you expect to encounter and warm the other bag similarly. Working as quickly as possible once a round is out of the bag, shoot it across your chrony and note the difference. You will then have a coefficient to change the powder charge to, depending upon what kinds of temps you will be shooting under. RL17 is truly a great powder, but designer powders are coming out regularly lately and just when you think you found velocity nirvana, another new one comes out that the manufacturer will claim is the second coming. My honest experience has been that powder manufacturers and I mean all of them, inflate their results. Some possibly more than others, but to expect to achieve their results, no matter how closely your test bed comes to theirs, is a fools errand. Just MHO.

John "Hoot" Hill