AR scout in 300 Blackout?

[TanklessPro]

I'm in the process of building an AR in 300BLK for plinking and hog hunting. I have been toying with the idea of a low power-long eye relief scope mounted forward, like a scout rifle. I'm thinking I could mount it down the rail on the handguard. I was thinking it would end up being pretty handy. Has this been done before? And how did or would it work out?

 

[The Big D]

It's been done and it works well. Gives you speed maybe a hair slower than a red dot, but some magnification for longer shots.

 

[eldon519]

If I were gonna do that, I'd use a cantilever mount and attach it to the receiver. Personally, I'm a bit suspicious of handguard-mounted optics.

 

[agtman]

I'm in the process of building an AR in 300BLK for plinking and hog hunting. I have been toying with the idea of a low power-long eye relief scope mounted forward, like a scout rifle. I'm thinking I could mount it down the rail on the handguard. I was thinking it would end up being pretty handy. Has this been done before? And how did or would it work out?

That was, essentially, the build I did for a dedicated hog slayer (primary use), and a short-range deer gun (secondary use), using my LMT MRP 5.56mm as the starting platform. I added a 10.5" .300BLK MRP barrel, and then topped it with a Burris 1x-4x illuminated scope, which I had laying around unused.

Yeah, technically, the Burris is more of a short-range tactical scope than a true EER scout scope, but the MRP allows it to be positioned as far forward on the rails as needed to work for your personal eye-relief. The set-up runs great and is very accurate. With 220gn sub ammo, it's zeroed for 50-yds. If I use the next lower hold-over dash in the reticle for POA, the same subs hit dead-nuts-on at 100yds.

I'll try to get a decent pic up later if the weather here clears. The only twist is that I run mine suppressed (SDN-6). Should I travel to hunt in a state where SBRs and cans are a "no-no," I've got a separate 16.1" .300 MRP tube to swap in.

 

[strambo]

I agree that a 1-4x optic makes more sense than an extended eye relief scope on the handguard.

Part of the reason for a scout scope was loading with stripper clips and being able to access the action, neither an issue with the AR design.

 

[agtman]

Bumped for a pic of my .300BLK MRP hog-slayer, as described above.

Scope is Burris's illuminated 1x-4x LRS in low ADM mount; can is an SDN-6. Everything else is mostly MagPul.

Zeroed at 50-yds/100yds, as described above, with Federal Am.Eagle subsonic 220gn OTMs.



All you hear is a big, heavy, nasty THWAPPPP! on the target ...

 

[DocUSMCRetired]

I would run a 6.5 Grendel instead of the 300 BO. But I would also run the March 1 - 8 FFP. This scope gives you 8X on the top end, and a true 1X on the bottom. With illumination it works like a red dot at 1X, but gives you that extra on top for long range shots.

 

[rbernie]

I'm in the process of building an AR in 300BLK for plinking and hog hunting. I have been toying with the idea of a low power-long eye relief scope mounted forward, like a scout rifle. I'm thinking I could mount it down the rail on the handguard. I was thinking it would end up being pretty handy. Has this been done before? And how did or would it work out?

I tried it with a 6.8SPC build, using both a 2.5x fixed IER scope and a Leupold variable 1.5x-5x IER scope. In the end, I found that I preferred an unmagnified Aimpoint for fast work, and a traditional 2x-7x class optic for longer work.

 

[Tirod]

Can it be done, yes. Mounting a scope that bridges the upper and handguard rail tends to void the warranty on the scope. The reason is that a free float does exactly that, wobbles around under stress of slings and rests, divorcing it from the barrel where traditionally the front site resides. It floats around. The barrel doesn't.

Eliminate the sight, you need to keep the optic on the upper. How much does the float move around? Nobody tests it - try it yourself on your rifle. To exaggerate the affect, mount the optic as far forward as you can and zero. Then sling up tight - pulling the crosshairs off zero. Take a few shots and see where you are now targeting.

Varying the pressure will vary the center of the group - which is why when it's done, it's a short range close in use. .300BO isn't considered long range, so it's consistent with that cartridge's ballistic envelope.

I'd be careful calling it a Scout rifle, tho. It does have a very specific and precise configuration and capability.

 

[Sam1911]

Basically, there isn't much reason (maybe NO reason) to mount your optic farther ahead than you need to in order to clear whatever parts or real estate on the gun you need to. Mounting a scout scope on a bolt-action rifle to get it out of the way of the top-loading action made some sense. Moving an optic forward on a rifle that has no need of such, isn't gaining anything. It isn't faster because it's farther away. You can't see more because it's farther away. It's JUST ... farther away.

With the good, decent, and even excellent low power and low power variable scopes available today, you can build an exceedingly fast-on-target AR that can be shot both-eyes-open very easily at lower magnifications, and then let you zoom to 4x, 6x, or even 8x, which is enough for shots way out farther than you have business shooting that round at a game animal, certainly.

 

[rbernie]

Moving an optic forward on a rifle that has no need of such, isn't gaining anything. It isn't faster because it's farther away. You can't see more because it's farther away. It's JUST ... farther away.

I'm going to disagree, based on my experiences alone. I have found that moving the optic further away from my eye does have a measurable speed benefit when snap shooting (both eyes open, like a shotgun), and can aid in proper rifle balance with lightweight barreled guns.

I have also found that variable scout scopes don't much work for me, and higher magnification scout scopes (e.g. 5x) are not as effective as the same magnification in a conventional eye relief optic.

 

[jmorris]

Yes, moving the optic forward can let you see more as anything blocking your view will be further from your eye. You can test this my putting a pencil 3" from your eye then move it 12" from your eye and see for yourself.

That said I don't have any optics mounted on AR handguards except for irons or red dot offset from primary (receiver mounted) for 3gun games.