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SOC's AR10-TU Magnum 300 RSAUM

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SOC's AR10-TU Magnum 300 RSAUM was created by SOC

Base Rifle - Armalite AR-10TU Magnum 300 RSAUM 24"
Stock - Magpul PRS
Grip - Magpul MIAD
Charging Latch - Badger
Trigger - Geissele Super Dynamic Enhanced
Handguard - Troy 13.8 MRF
Gas Block - PRI Adjustable
Muzzle Break - Surefire SFMB762

Scope - Millett 6-25X56mm, Millett low pro rings and Swamp Fox base.
(Placeholder tell I can upgrade to a Nightforce ATACR in a Larue LT745 20moa Mount.

I plan to add an Accu-Shot Atlas bipod and monopod to round out the system.

I have a Voodoo Shooting mat, drag bag, backpack combo that holds my Bushnell spotting scope, Leica 1600, Log and Dope books as well as a cleaning kit. I hope to add the new Kestrel 4500NV Applied Ballistics Meter to that to round out my spotting gear.

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After a long hiatus while I gathered funds, it is finally ready to shoot again.

I welcome any questions and comments. I'll be taking it to the range hopefully this weekend.
Last edit: 10 years 9 months ago by SOC.
10 years 9 months ago #25660

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Replied by SOC on topic SOC's AR10-TU Magnum 300 RSAUM

Was trying to post this in

Forum - 'The' Rifle - Armalite AR-10
10 years 9 months ago #25661

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Replied by faawrenchbndr on topic SOC's AR10-TU Magnum 300 RSAUM

Very nice..........

Reminds me I REALLY need to get a better spotting scope.
NRA Life Member
USAF(ret)
10 years 9 months ago #25662

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Replied by Lizardette on topic SOC's AR10-TU Magnum 300 RSAUM

Pretty awesome looking rifle.

I want to know how well that PRI gas block works.
10 years 9 months ago #25667

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Replied by SOC on topic SOC's AR10-TU Magnum 300 RSAUM


I love the PRI on all the barrels for my MGI modular rifle. It allows me to tune the gas system to the ammo to reduce ware and fouling and improve reliability. It also allows me to use the same weight buffer and spring in .223/5.56, 5.45x39, 6.5 grendel, and 7.62x39 by gassing each barrel for optimum reliability with given ammo. I keep a dope book for sight adjustments for each caliber and loading as well as the optimum number of turns from fully closed the gas system should be set at.

On the RSAUM I shoot bullets from 110gn V-Max to 210gn VLD and it became very apparent an adjustable gas system would be a must from a reliability standpoint. That prompted my replacement of the stock FF tube and gas block to the Troy MRF and PRI gas block.
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10 years 9 months ago #25669

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Replied by Lizardette on topic SOC's AR10-TU Magnum 300 RSAUM

Can't remember, and I'm extraordinarily lazy right now, so: How does it adjust again? Set screw? Because seriously that's my LEAST favorite way to adjust gas pressure.
10 years 9 months ago #25674

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Replied by SOC on topic SOC's AR10-TU Magnum 300 RSAUM

Allen screw.

Why it that so bad?
Last edit: 10 years 9 months ago by SOC.
10 years 9 months ago #25675

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Replied by SOC on topic SOC's AR10-TU Magnum 300 RSAUM

Went to the range today and shot up 60 rounds of Remington 165gn and 180gn Core-Lokt PSP ammo to zero and practice. The 165gn was more accurate but I shot that up before I started grouping. Was getting sub MOA 3 shots from the 165gn.

Here is a 10 shot group.

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No bipod, just using a backpack and my fist under the stock to adjust elevation. Nothing to wright home about. Need to work on my form, wish I would have saved some 165gn for last. I have some 190gn Remington BTHP that I think will do better before I get to my handloads.

Need to get an Atlas Bi-pod and Accu-Shot mono-pod ordered.
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10 years 9 months ago #25716

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Replied by Lizardette on topic SOC's AR10-TU Magnum 300 RSAUM

My experience with adjustable gas systems in general has not been good.

My complaints about set screws (in no particular order) are thus:

1. Requires a tool to adjust.

This isn't a big deal to a lot of people. I really prefer things that can be adjusted without tools, especially when you anticipate needing to change it.

2. Continuous adjustability.

The fact that it is continuously adjustable isn't the problem. The lack of definite settings makes it harder to exactly repeat a given adjustment. That's not to say it's impossible to do. I'm just lazy about some things and this is one of them. I'd rather have definite settings that lock into place, even if it's just with a ball detent.

3. The screw isn't captured in any way.

I'm not worried about it falling out completely so much. My experience has been that non-captured screws back out under recoil though, changing your gas setting, possibly throwing off your accuracy, and possibly decreasing reliability. Blue lock-tite can help alleviate this problem, when the screw does not get heat applied to it with every shot. In my experience blue lock-tite goes liquid pretty quickly when it's applied to a screw holding anything attached to a gas system. It heats up and the screw backs out, unless...

4. Fouling.

Oh my dear lord... Fouling. When the passage through a gas system is partially obstructed (as this is how set screws "adjust" gas flow), powder residue builds up on it. If you don't remove it and clean it often, eventually it will build up to the point that the screw gets stuck in place and the passage through the gas tube starts getting considerably smaller. It's a real... thing, to get enough torque on one of those small allen wrenches to un-stick a carbon-ed in screw.

... I think that's it.
10 years 9 months ago #25717

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Replied by Lizardette on topic SOC's AR10-TU Magnum 300 RSAUM

Always good to see a real target, and a ten shot group at that. :twothumbs:

Keep up the good work. :)
10 years 9 months ago #25718

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