7 mm SHERMAN SHORTMAG vs 7 SAUM

[wilkup]

I'm all set to try some *HOT* loads with my 180 Hybrids in the next couple days.
I've got 65, 66, 67gr of RL26 to try out after seeing how the 67gr performed with the Sierra 140gr SBT, I'm eager to check out the performance with the heavier Berger round. I'm hoping for 3150', but would be happy if I hit 3100+ fps. I don't think it's unreasonable to expect those speeds after hitting just over 3000' with my 63.5gr load of RL26. The barrel has been broken in now and I expect it will handle the hotter loadings =)
Will keep y'all posted on how things go. I'm planning to get a brake thrown on the end of this barrel in the next week or so as well to help mitigate recoil, as these hotter loads are taking recoil into the realm of discomfort.

 

[elkaholic]

I'm all set to try some *HOT* loads with my 180 Hybrids in the next couple days.
I've got 65, 66, 67gr of RL26 to try out after seeing how the 67gr performed with the Sierra 140gr SBT, I'm eager to check out the performance with the heavier Berger round. I'm hoping for 3150', but would be happy if I hit 3100+ fps. I don't think it's unreasonable to expect those speeds after hitting just over 3000' with my 63.5gr load of RL26. The barrel has been broken in now and I expect it will handle the hotter loadings =)
Will keep y'all posted on how things go. I'm planning to get a brake thrown on the end of this barrel in the next week or so as well to help mitigate recoil, as these hotter loads are taking recoil into the realm of discomfort.

Wil.....You have 40 grains more weight that you are trying to push! I would be VERY surprised if you can shoot more than 64 grains without destroying your brass. Just a word of caution......Rich

 

[wilkup]

I will check each piece of brass after firing and stop it things get too crazy. Even at 67gr, I was only slightly compressed...

 

[elkaholic]

I will check each piece of brass after firing and stop it things get too crazy. Even at 67gr, I was only slightly compressed...

I don't mean to dampen your enthusiasm to find max and I do appreciate your testing. I am just basing this on testing in my rifle. I have a 26" barrel and my hunting load is 60 grains behind a 180 vld for 2985'. I can shoot accurately, and safely at 62 grains for about 3080'. I have fired 63 grains at over 3100' but felt that I was reaching safe limits. Your barrel could be a little different, but probably not that much. Good luck with your testing and do let us know how you come out......Rich

 

[wilkup]

I don't mean to dampen your enthusiasm to find max and I do appreciate your testing. I am just basing this on testing in my rifle. I have a 26" barrel and my hunting load is 60 grains behind a 180 vld for 2985'. I can shoot accurately, and safely at 62 grains for about 3080'. I have fired 63 grains at over 3100' but felt that I was reaching safe limits. Your barrel could be a little different, but probably not that much. Good luck with your testing and do let us know how you come out......Rich

Maybe I'll give RL33 a try too and see how it does with a compressed load too. I don't think I can get enough powder in there to create dangerous pressures.
What do you think about that?

 

[elkaholic]

Maybe I'll give RL33 a try too and see how it does with a compressed load too. I don't think I can get enough powder in there to create dangerous pressures.
What do you think about that?

I think 33 is too slow for the 7ss, but you can try it.

 

[wilkup]

Ran through my ladder this morning starting with 64gr and working up to 65gr. I didn't pull the trigger on anything over 65gr though.
Conditions
Temp: 73*
Humidity: 91%
Pressure: 30.08 rising
Elevation: 900'
My speeds with 65gr loaded to 2.95" COAL were as follows:
3126'
3141'
3133'
3138'
3126'
Which averages out to ~3133fps

Bolt lift on extraction was not stiff but there were slight marks from the extractor. I'm gonna try the accuracy out of this loading when I get a chance but as it stands now, I think I've found the load I want to use if it's within 1/2MOA.
I'm really starting enjoy this little SS case!

 

[elkaholic]

That is pretty impressive with a short barreled rifle Wil! It shows the efficiency of the cartridge. Also, you must have a little looser barrel, or slower powder lot than mine. That is a pretty hefty charge.........Rich

 

[wilkup]

That is pretty impressive with a short barreled rifle Wil! It shows the efficiency of the cartridge. Also, you must have a little looser barrel, or slower powder lot than mine. That is a pretty hefty charge.........Rich

Would the difference in elevations between us have anything to do with pressures experienced?

 

[elkaholic]

Would the difference in elevations between us have anything to do with pressures experienced?

No.

 

[wilkup]

Well after a couple days, I couldn't leave well enough alone in my short, 23" barreled gun and decided I'd try an even stiffer charge of RL26 on the little SS case and see how things went. I've got a serious case of need for speed and realistically should just run a bigger powder column. Since that's not currently an option, I'll settle for hotrodding this little case instead. I think this will be my stiffest load. Definitely visible extractor marks and bolt lift was a bit stiffer than I'd care to experience with any sort of regularity! Still fun to play though gun)

66.0gr RL26
2.94" COAL
Berger 180gr Hybrids
CONDITIONS
Temperature - 68 degrees
Humidity - 90%
Pressure - 30.29 steady
Elevation - 900'

FIVE SHOT STRING
3237'
3253'
3221'
3232'
3235'
Average: 3235fps

 

[DocDoc]

Any estimate for pressure? Quick load?
70k plus?

 

[wilkup]

I don't have access to pressure equipment, just have to rely on signs for when I'm getting into the realm of too hot/dangerous. Been the fortunate fool who blew a primer loose in my past and try to stop well before that happens now. It'd be interesting to know where the load's at pressure wise, because the pressure signs aren't as apparent with these Improved type shells I'm told.
Right now, I think I'll stick with my 65gr loading as that gave awesome speed, good SD, and no stiff bolt lift or loose primer pockets.

 

[Edd]

I think shooting a 180 gr 7mm bullet at 3235 fps from a 23" barrel and a 7 SAUM size case is something less than intelligent.