7mm RM and loads using 175 SMKs

[craigp40]

I'm getting ready to start putting together loads for my new 7mm RM. I picked up a box of the 175 SMKs and plan to start with RL-22. Any other powders you guys have had luck with when shooting this bullet? I've also got RL-25, but wondering if it might be too slow.

Also, I don't see many guys shooting this bullet. Any particular reason? Should I be looking more closely at the lighter A-Max or Accubond?

 

[Kenster-Boy]

I don't know what twist your barrel has but mine is a 1 in 9.5 and it is just not quite fast enough to stabilize anything over the 150-160 range. Hope this helps. Only time and a little burnt powder will tell.

 

[Varmint Hunter]

7mm Twist rate

My 7STW has a Hart 10" twist barrel. I was a little skeptical about its ability to stabilize the looong 162gr A-Max bullet until this weekend. I had no problem shooting .5moa @ 200yds.

However, those long *** A-Max's will not fit in the magazine when the bullets are loaded out to engage the rifling. The Sierra MK's will fit in the magazine when loaded out to engage the rifling.

Still looking for the perfect antelope bullet for the often windy conditions of Wyoming. /ubbthreads/images/graemlins/cool.gif

VH

 

[harvey]

I use 140 gr spitzer(sierra) and 139gr BTSP(hornady) with short cut 4831. Both lit with 210m. I find that this gun likes 64 gr. This is a 26" 1:10 off the shelf winnie. If I were playing with 175's, I'd use my 300 RUM.

 

[brianwinzor]

Craigp40, I owned a Rem 700 classic in 7mmRM in the mid 80's, so naturally I didn't have the opportunity to use the Sierra 175 MK. However, I did chronograph and test the 175 Sierra GameKing, as well as the 120 & 140 Nosler BT's.

Judging from my results, I am sure that Re 25 will be not be too slowburning for use with the 175 grain bullet.

Using Remington cases, I found that to fill the case to the base of the neck, it took about 76.0 grains of a long cut extruded powder such as IMR 7828, and 83.5 grains of ball powder such as H870. I estimate that a short cut extruded powder such as Re 25 would have occupied about 78 - 79 grains. My chrono results with the 175 MK,Rem cases, Fed 215 primer, were:
65.0 grains IMR 7828 - 2740 fps
66.0 grains IMR 7828 - 2808 "
67.0 grains IMR 7828 - 2883 " (Max)

76.0 grains H870 - 2841 fps
77.0 grains H870 - 2901 fps
78.0 grains H870 - 2977 fps (Max)

Generally most people tend to use the 140/150 grain bullets for medium game, and use the 175 grain bullets for larger game. I have not heard how the 175 grain MK performs in the field. Regards,Brian.

 

[craigp40]

Thanks for the input guys. The rifle I'm having built will have a 1 in 9 twist, so I'm hoping it won't be a problem. Primary reason I'm choosing this bullet is its high BC for the longer range stuff out to 1000yds (steel plates at 1000 and PA deer 500-700). Could possibly use it on elk someday, but not in the near future. However, I have a 300RUM to fill that ticket if needed. I have been reading that most guys are really liking the RL-22 and H4831 for this cartridge. Not sure if you guys have seen the 175 SMKs, but I sure was impressed. No wonder that bullet has such a high BC.

 

[Brien]

i think a 9.5" twist is adequate depending on climate.. i live in WV and have shot a few out of a stock sendero 7SAUM however so far the 162 Amax is outshooting it... i will be trying the 175SMK in dad's 7ultra sendero and maybe his 9"twist custom 7rem mag but not for a couple more weeks....
Brien

 

[besauve]

I don't have a 7 RUM nor have I shot 175 SMK's in 7mm, but when I was experimenting with different powders, including R22, for my 7mm S&H, I ultimately ended up with H4831SC (64 grains coincidently) below 180 Bergers. The combination shoots very well. If you are not having luck with the other powders, give H4831 a try.

 

[chris matthews]

Craig,
I wasn't thinking the other day when you asked about this and the box saying 1-8 was needed- well, 1-8 is needed for a 7-08, the faster you push a bullet (to a degree) the slower twist you can get away with. Your 7 RM will do just fine.

 

[craigp40]

No problem Chris. I trust your judgement. Hell, if the box said requires 1-3 twist and you said this rifle would stabilize it, I'd probably believe you /ubbthreads/images/graemlins/smile.gif. I already loaded up some 140 Gamekings just to break in the barrel. Had them laying around from my dad's 7mm, plus no reason to shoot expensive bullets until the rifle is ready for load development.

 

[tsiero]

My light 1000 yard BR gun is a 7mm Rem with a Hart 28.5 barrel. I shoot 176gr GTB bullets with 65.5gr VV-170. I use RWS brass and Rws Mag primers. Twist 1/9 and I need 2950fps to make this combo work. I put a new Schneider barrel on it and rechambered in a 7mm Rem mag IMP. With 68.8gr of Retumbo the Sierra 175grMK worked well velocity is about 3120fps. Using RWS brass, Fed 215M primers. I found that treating the barrel and bullets with Fastex increases the velocity by about 100FPS.