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Armalite DEF10 battle rifle with KeyMod+UBR


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So here is my Defender 10 with the Armalite 15" KeyMod rail and UBR. Function has been 100% so far over about 70 rounds of PMC 147gr FMJ. Both the IMI 20 round mags and the PMAG LR 25 round mags work great, hold the bolt back after the last round, and drop free full or empty. I'm using a standard AR15 carbine spring and a heavybuffers.com CAR10 heavy buffer with the UBR. I am thinking about cutting my standard Armalite AR10 carbine spring to 24 coils to mimic how heavybuffers.com mods their springs...

I also used a little jig I got from Rainier Arms a while back to dimple the barrel for the set-screw type low-profile gas block. I tried to use one of the clamp-on gas blocks I have laying around but none would adequately clear the inside of the handguard.
Primary optic is a TA11D with a red-illuminated .308 horseshoe reticle; I believe this config with the FDE anodizing and SDO-type lens caps was exclusive to RSR. Secondary is an Aimpoint Micro H-1 on a Burkett offset mount.
Weight is 10.5lbs with no mag inserted. IMHO that's not half bad. Plus, the UBR pulls the weight toward the rear of the rifle, which in turn aids in balance.
The Armalite 15" freefloat KeyMod rail deserves special mention. First, it does not just clamp onto the barrel nut. In the photo below, the red lines indicate where the very beefy bolts that clamp the handguard together also interface with grooves on the very large barrel nut to ensure the handguard does not slide forward. Once mounted, the Armalite handguard isn't going anywhere.
In addition, there is a pocket on the right side of the handguard that captures the ejection port door rod so you don't need to use a longer AR10(T) type rod with this freefloat handguard.
Finally, notice the sleeves on the bolts? Those ensure you can't overtighten the bolts and break them.
The Armalite unit is very well thought out, IMHO. It is also very reasonably priced.
Very happy with this rifle! However, the little red guy with horns that sits on my left shoulder keeps whispering about swapping the barrel out for one in 6.5 Creedmoor so I can shoot handloads using the new Berger 130gr AR Hybrid bullets... :P
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The IMI mags are very nice and the followers ride smoothly in the bodies. Spring tension seems just right. I can load a full 20 rounds and seat the mag with the bolt closed. The windows are not "calibrated" like the ones on the Magpul LR25s, so not quite as useful but I guess they're good to see if there are SOME rounds remaining. I'll take more photos when I get a chance...


As a quick update, I've shot the following ammo through the rifle so far:

- PMC 147gr FMJ .308Win: 100% function over 90 rounds, very nice ammo;
- Hirtenberger 147gr 7.62NATO: 100% function over 20 rounds, great value for the price;
- FN 144gr 7.62NATO, vintage 1981: 100% function over 5 rounds, have a bunch of this so good news;
- DAG 150gr Bimetal 7.62NATO: consistent short stroking, no-go in this rifle.
No real accuracy testing, but my various targets seem to indicate a 1-2MOA rifle depending on ammo. When I get a longer range session I'll shoot some of my standard precision ammo, which is the Hornady 168gr Amax factory load.
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Where did you find the Dag brother haven't seen any at reasonable price for some time ??? My RRA loves that stuff.

Rene...keep an eye on SPS for your bulk ammo. The blem deals on nice match ammo are great and get better if you buy in bulk. I recently bought a case of 168gr SSA OTM For about .60/rd with free shipping. They have 15% off right now. http://www.shootersproshop.com/
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Nice looking rifle, glad the Armalite rails are working out, I'm planning to get the national match rifle-length quad rail. I'm working on upgrading my DEF-10 myself and I'd like to know what flash hider is that? It looks M110-ish.. and since I'm going for the M110 look I think that would be a better fit than the factory piece, I'd rather not have my new barrel cut for 3/4 threads if I can avoid it.

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