My new build in 7mm Remington Mag. (chrono #'s)

[threewood]

Long time lurker, first time poster. This will be my first journey into distances beyond 500 yards. This was my old hunting rifle that I decided to turn into a range toy.

Here are the specs:
- H-S Precision Police stock, grips and forearm were textured with acraglass gel, camo was applied with alumahide II (desert tan, olive drab, and flat black). The action was bedded with
acraglass gel mixed with atomized aluminum. The stock channel was perfect for the barrel and needed no extra inletting.
- Shilen SS Match Select, 27" final length in .284/9 , in #7 heavy varmit contour. Chambered in 7mm RM. Target crown and blasted finish provided by Louisiana Precision.
- Holland recoil lug, which, to the surprise of my gunsmith was very flat
- Jewell HVR trigger. Well worth the money.
- Ken Farrell 20moa base and standard rings in 30mm. The base was bedded to my action with JB Weld.
- Vortex Viper 6.5x20 x 50, with target dot and sun shade. Very nice glass and was heavily discounted because the reticle was being discontinued. Seems to track spot on so far, haven't done much testing yet.
- Harris bi-pod.
- Eagle stock pack (with thin Budweiser can coozie underneath to raise cheekweld)
- Stock Remington BDL bottom metal

All the action and barrel work was done by William Roscoe at Louisiana Precision. He is a true craftsman and a pleasure to talk to. He knows his stuff.

For a magnum, it kicks like a .308. Probably due to the weight being around 16 pounds. It fits very nice and is very comfortable to shoot. I have only put 20 rounds (139gr and 175gr over H4831) down range so far, to get it on paper and toy around but it seems to be a shooter. I just picked up some Retumbo to try out with some 162gr AMAX bullets.

 

[JCH]

Re: My new build in 7mm Remington Magnum

Looks good!

 

[RobG]

Re: My new build in 7mm Remington Magnum

Looks good. I run a 7mag myself, same Viper (Mildot) with a Krieger barrel. I didn't get great results with Retumbo in mine finding R22 to work the best with the Amax. I get comments all the time about recoil but at 16.5 lbs is isn't bad at all.

 

[Kells81]

Re: My new build in 7mm Remington Magnum

I dont see it listed so I will venture to ask, what is the item in the last pic? Looks like a torque mechanism of some sort but figured I would ask.

 

[RobG]

Re: My new build in 7mm Remington Magnum

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Poke</div><div class="ubbcode-body">I dont see it listed so I will venture to ask, what is the item in the last pic? Looks like a torque mechanism of some sort but figured I would ask. </div></div>

Thats the Borka torque driver. I think they are selling them here in the ccommercial sales area. Pretty neat actually. Every hole is a torque value and when you hit the specific value, the handle "breaks" over.

http://www.youtube.com/watch?v=vDFKcxfAptA check out the video

 

[threewood]

Re: My new build in 7mm Remington Magnum

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: RobG</div><div class="ubbcode-body">Looks good. I run a 7mag myself, same Viper (Mildot) with a Krieger barrel. I didn't get great results with Retumbo in mine finding R22 to work the best with the Amax. I get comments all the time about recoil but at 16.5 lbs is isn't bad at all.</div></div>

R22 would have been my first choice after reading up about it on line but my local gunshop never seems to have any. They always seem to have Retumbo and h4831 though. I might also give H1000 a try if I don't find a good load with the others.

 

[kortik]

Re: My new build in 7mm Remington Magnum

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: RobG</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Poke</div><div class="ubbcode-body">I dont see it listed so I will venture to ask, what is the item in the last pic? Looks like a torque mechanism of some sort but figured I would ask. </div></div>

Thats the Borka torque driver. I think they are selling them here in the ccommercial sales area. Pretty neat actually. Every hole is a torque value and when you hit the specific value, the handle "breaks" over.

http://www.youtube.com/watch?v=vDFKcxfAptA check out the video </div></div>

Borka Tools Torque Driver

 

[jdwelch10]

Re: My new build in 7mm Remington Magnum

I just finished building a 7 mag myself. I have been running the Amax's over 4831sc and I think it can do better. I'm going to give the 168 gr bergers and a few other powders a try. Thinking retumbo and h1000. Let me know how the load development goes.

 

[jdwelch10]

Re: My new build in 7mm Remington Magnum

Oh and The rifle is a schnieder 5.5 contour, 26" barrel, 1-9", in a McMillan a-5. Work done by hill country rifles.

 

[threewood]

Re: My new build in 7mm Remington Magnum

Finally got out to the range to try a couple of loads. I had 20 rounds loaded up with Retumbo and 20 with H4831sc, all pushing 162 amax bullets. It was a wonderful day, 102 degrees with a cross wind from 5-25mph straight across the targets (my target stand was actually moving some degree as well).

All shots were at 100 yards with scope set on 8x, paralax was set around 130 yards (the only setting the dot didn't move around), and there are 5 shots in each group. 2 hours to put 40 rounds down range.

Sorry for no velocity numbers, my chronograph doesn't get here until Wed.

First 4 groups were shot with Retumbo (69.0, 69.5, 70.0, and 70.3)pushing 162 amax. The 69.0 and 70.0 groups being the best of the day. The 4th group was the worst, and only .3gr higher than the best? All were set with .007" of jump. No signs of overpressure.

The last 4 groups were shot with H4831sc (63.5, 64.0, 64.5, and 65.0) pushing 162 amax bullets. I was not impressed, all were set at .01" of jump. Smallest of these was .717" and largest being 1.045" No signs of overpressure.

I will go back out and try H4831 again when the weather is better and shoot them first before the barrel heats up. I will also clean the barrel to see if that doesn't improve the numbers.

 

[mdesign]

Re: My new build in 7mm Remington Magnum

Nice rifle...gotta like those 7RM, great caliber that can do almost anything well with manageable recoil.

 

[vman]

Re: My new build in 7mm Remington Magnum

Nice rifle mate... i love the 7mmm mags they are a great calibre.

Groups look sweet man especially that 3rd one. Im sure you can squeeze more out of her

 

[wnroscoe]

Re: My new build in 7mm Remington Magnum

Group 3 looks like it was .203" after the bullet deduction. Looks good.

 

[threewood]

Re: My new build in 7mm Remington Magnum

Another update with chronograph numbers. Competition Electronics was the chronograph used.

Wind was 5-7mph straight into my face, 95 degree temp. All shots were seated .005" off of the lands. 162gr Hornady AMAX on all rounds over Retumbo, R-P cases, CCI mag primers.

1st string, 69.0gr of Retumbo, 5 shots:
-2930
-2930
-2969
-2930
-2936
Avg. 2939fps, ES 39, SD 16. Group size was .571"

2nd string, 69.3gr of Retumbo, 5 shots:
-2976
-2949
-2989
-3037
-2923
Avg. 2974fps, ES 114, SD 43. Group was large as you can see.

3rd String, 69.6gr of Retumbo, 5 shots:
-2956
-2943
-2982
-2982
-3003
Avg. 2973fps, ES 60, SD 23. Group was .458"

4th string, 70.0gr of Retumbo, 10 shots:
-2989
-2976
-2982
-2989
-3044
-2943
-2982
-3003
-2962
-3030
Avg. 2990, ES 101, SD 29. Group minus the last shot called flier was .664"

All of my loads were hand thrown, same brass lot on all cases, primer pockets uniformed and flash holes uniformed as well. I think I have some variation with neck tension. All the cases were full length resized with shoulder bumped back .001". With some, the shoulder was pulled forward with the expander so I had to dink around to get them all bumped the same. I may have to get a neck sizer and see if my numbers don't even out a bit more. Any thoughts?

 

[260shtr]

Re: My new build in 7mm Remington Magnum

The 69.6 load looks good. Get rid of the expander ball for more consistent neck tension. I also shoot a 7 RM and your #'s seem low for Retumbo. I use Winchester brass, that might explain it. I tried Retumbo and the E/S was about like yours. I switched to H-1000 and that dropped the E/S to 15 or below.

Back to the 69.6 load. Take it out to 400-500 yards and check the vertical dispersion. The velocity will pick up a little with more rounds down the barrel.

Edit to say I just looked at my notes and your velocity is right on. I shoot 168 Bergers and 70.5 H-1000 for 3035fps. It took 71.5 to get the same velocity with Retumbo.