Hello from CO. Building my first 7MM Rem Mag

N

NFHunter

Member
Joined
Apr 9, 2023
Messages
7
Location
Colorado
Hi all, this is my first post here! Seems like a super cool place and I'm excited that there is a classifieds section where I can potentially buy a scope for this build. I selected some components (which I already bought so likely not changing it now) and have a gunsmith lined up to machine the chamber and thread barrel etc. Here are the components:

-Zermatt Bighorn action w/ 20 degree picatinny
-7mm SS BARREL BLANK 8.5 twist 26" (will be fluted and Cera-Coated)
-H-S Detachable Magazine bottom metal
-Jewell Trigger
-Carbon Fiber Mesa Altitude Stock

I have a Surefire Socom 300 SPS Silencer I plan to use with this build. Will 26" barrel plus the suppressor be too long / heavy? Should I just put a flash hider on it and forget the silencer? Maybe just do a 24" barrel and potentially suffer 75-100 fps velocity drop? I do primarily plan to use this as a hunting rifle but even with the long barrel and suppressor it will probably be lighter than the AR I've been hunting with.

Does anyone have scope recommendations for a build like this? I'd like to be able to shoot out to 600-700 yards maximum.

I plan to reload my own ammunition. I've already ordered some Norma brass but am trying to decide on the bullet weight and powder. I'm thinking Hornady ELD-X 162 grain. Still need to purchase the powder. Any thoughts?

I'm excited to get my first longish range bolt action built as my previous builds have only been AR style rifles.

Cheers from Colorado
 
Welcome from Colorado.
Look up load data with Hammer bullets and RL26 for a fast light load. I use H1000 and Berger 168g classic hunters in 2 rifles. I don't have a suppressor so can't comment on that, I use muzzle brakes.
 
I have a 26" Sendero contour barrel on my 7mmRM. No suppressor and no break. At that length, it balances quite nicely. If you are hard over on running the suppressor, you might think about a shorter barrel. At least that seems to be the prevailing preference amongst those that run them.
As for scopes, I've become quite fond of the 5-25x56 Nightforce ATACR's with the MOAR reticle. Whatever scope you end up with, make sure it's a good one. At the end of the day, you'll have a hard time killing what you can't see...
 
Howdy from Colorado as well, this is a great forum. These are just personal opinions, 7mm rem mag, awesome cartridge, nothing in this state you can't kill with. Barrel length, 24" is plenty enough if you plan to hunt timber or the cedars, if it's only a plains rifle you can go longer. Velocity loss is mostly insignificant at your max range of 700 yards. Scope and reticle choice is mostly personal, anything from $800 on up will get you something decent enough, personally keep your reticle fairly clear of unneeded lines, they only get in the way for closer in shots. If you're shooting 160 class bullets imr or h4831 would serve you well and I see it on our shelves out on the western side of the state now, those really slower powders rarely show up out here. Have fun with your build, good luck with hunting
 
Thanks for the tips!!

I do like the Nightforce scopes I've looked at online. I'm hoping that a 5-25x56 isn't too heavy. Also, I've always thought that that a first focal plane scope was superior but looking around the forum it seems that a lot of hunting scopes are actually SFP. Wouldn't a FFP be better incase you aren't zoomed in all the way and want to hold over using the lines on your reticle?

I'm now leaning toward the 24" barrel. I didn't want to limit myself but I also believe in going with what is practical and outgrow your gear before upgrading. If I am trying to reach distances that are being limited by a 24" barrel, it would be a good problem to have because I would have to start building a new firearm, haha! Also with my 6" suppressor on, would that increase the pressure and thus velocity beyond a 26" barrel? The suppressor has a quick attach muzzle break that is installed on the gun and it's super easy to install and remove after that, so can be shot in both configurations.
 
Typical velocity loss would probably be closer to 25-35 fps per inch, so your estimate is probably on the pessimistic side for going from 26" to 24".

I get ~2950 fps out of my 26" bbl with 175 grain bullets. Take 120 fps off that for a 22" bbl that puts you at 3100 ftlbs. To get 3100 ftlbs from a 162 grain bullet requires 2940 fps. Let's be conservative, and call it 2900 fps.

At 2900 fps, 4000' elevation, 50° F, you'll have ~2030 fps, and ~1490 ftlbs of energy at 700 yards with a 162 gr ELD-X. That's just a smidge below what I'd call "plenty" for an elk, but I'd certainly feel comfortable taking that shot if I knew I could hit the boiler room.

In summary, with your 700 yard limit, and a good sleek bullet (162 ELDX, 168 Berger, 175 ELDX or Nosler ABLR, etc), you should have enough power for reliable expansion and penetration on elk sized game.

I vote on being a weirdo, and going with a 23" barrel just so you can be different...🤪
 
entoptics said:
Typical velocity loss would probably be closer to 25-35 fps per inch, so your estimate is probably on the pessimistic side for going from 26" to 24".

I get ~2950 fps out of my 26" bbl with 175 grain bullets. Take 120 fps off that for a 22" bbl that puts you at 3100 ftlbs. To get 3100 ftlbs from a 162 grain bullet requires 2940 fps. Let's be conservative, and call it 2900 fps.

At 2900 fps, 4000' elevation, 50° F, you'll have ~2030 fps, and ~1490 ftlbs of energy at 700 yards with a 162 gr ELD-X. That's just a smidge below what I'd call "plenty" for an elk, but I'd certainly feel comfortable taking that shot if I knew I could hit the boiler room.

In summary, with your 700 yard limit, and a good sleek bullet (162 ELDX, 168 Berger, 175 ELDX or Nosler ABLR, etc), you should have enough power for reliable expansion and penetration on elk sized game.

I vote on being a weirdo, and going with a 23" barrel just so you can be different...🤪
Click to expand...
23.35" barrel?!?
 
Welcome to the forum. 24" barrels seem to be a sweet spot on 7RM with or without a can. I would actually prefer a little shorter with my 7" can due to the areas I typically hunt. Rifle scopes are primarily a personal preference component. With your max range the door is wide open. Budget and weight will be key determining factors in what you decide. The FFP vs SFP is also a personal preference thing. You are well on your way to having a fine hunting rifle. Best of luck on your build and keep us posted.
 
Welcome from central Arizona! Certainly share your build with us. I have a 7RM and a 280AI and love them both. I had good success in 7RM with 180, 168 Berger VLD hunting and just recently the 143 Hammer Hunter.
It will shoot everything in between. Lots of choices in this chambering.
I run a Leupold and Zeiss on these to keep weight down and glass is great for the price. 20 moa pic rails on both. Nightforce, even better scope.
My 7RM has a braked 26" 1:8.5 twist heavy sporter. I like the stiffness. Weight is 10.5 pounds unloaded. I think it would be too long suppressed so I would cut it back to 24" or less if I ran a can.
I have a Trigger Tech on both rifles. Very smooth.
7RM is a great open country chambering.
 
I hate cans and opt for Gentry muzzle breaks instead, reducing the recoil to a 25/06 level, sound thrown forward with forward-slanting ports.

160-168g
69-71.2g of Retumbo, Fed 215
3100 fps with small sub 1/2" groups
I use Remington brass. Starting over, I would use AGD brass as it is very tough brass, and adjust load for different capacities.

68-69g of R#25
Win Mag primer
Tiny groups, and sub 10 fps SD

H4831 is very accurate but slow

61g of IMR 4350 Rem case, Rem 9 1/2 is 3000 fps, and work up to this load

I run standard magnum sporters to #5 contours cuz I alike shooting dot size groups.

The 162g ELDM maybe a better bullet for deer than the X due to expansion.
 

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