SLR tips, tricks and observations

B

Betty-Lou

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Location
West Kootenay, BC
While I've messed around with AR's a bit this was my first from scratch build. I'm going to list a few things that caught my attention, that I think may be specific to the SLR, but maybe not.

According to MDI these are sold as " TIGHT units", so.......

CHECK YOUR BOLT CATCH PIN HOLE BEFORE DRIVING THE PIN HOME AND CRACKING YOUR MOUNT!!


1. The trigger box is held in place with a screw that uses a T9 torx. I mention this because the sets I had only went down to T10.

2. I had to install the hammer loosely first in the trigger box, then the trigger. I believe this is different from an AR.

3. Some of the pin holes are on the tight side. When I went to install the bolt catch pin it was so tight it started to crack the mount. So I took it out and emery clothed the pin a bit to get it in.

4. The dust cover "shaft" wouldn't allow me install my handguard because it stuck out too far. On closer inspection I noticed that where the c clip is on the shaft and the position of the mounts on the receiver, the pin wasn't reaching the mount on the butt stock side. Instead of notching my handguard, I removed the c clip which allowed the shaft to reach the other mount and fit flush with the handguard side mount.

5. If you order a normal LPK you will have a few parts left over, don't be alarmed.
 
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The anodizing on mine is good.
Had to notch my Odin o2 lite handguard for the dust cover pin area. I believe my pin length was fine but the width at that point, the pin housing, was about a 1/16" more than the inside diameter of the handguard.
My bolt catch pin was stupid tight. After wrecking 2 pins I used a needle file on the hole. I don't quite understand the logic or aesthetic choice of having more material on either side of that pin as it makes the install and removal a giant PITA. *Edit* I see now its wider due to the trigger box.
The Phase 5 extended bolt catch fits and operates nicely, does not contact the receiver unless you slide the upper off too far/quick.
The sliding fit of the upper and lower is super tight, which can be good but is also a pain in the ass to separate and can easily slide too far and smack into the bolt catch if you aren't careful.
Safety selector is good
Trigger box is a ####ty thing as it limits the trigger options, I knew this ahead of time but I will probably modify it to fit a trigger pack or my Hiperfire. The fit of the trigger box itself is excellent but the mil spec trigger is still a PITA to install as you have to do it backwards from normal and pushing the disconnector from the top to line up the pin hole took me a while. It is also held in place with a number 9 Torx.
My metal mags do not seat unless smashed and then need to be wiggled hard to remove. Polymer mags dont quite drop. All magazines seat and drop free with the lower only, they are only tight with the upper attached.
I dont love the takedown bolt but again I knew that going in.
My endplate was fine
Buffer install was fine
Had to keep my grip loose so I could install the endplate and trigger guard pin. I used an Ergo grip so maybe there was just some excess rubber on the grip.
No issues with the handguard rail lining up, the Raptor charging handle, low mass BCG, headspace, dust cover fitment, extended mag release or anything else really.

Overall I am pretty happy, there are a couple small issues that I would have expected to be sorted out for $1,000 of my hard earned money but what can you do. I have also ordered an atrs set for comparison & will see when it gets here.

Specs:
Luth AR MBA 3 buttstock
Generic buffer tube,endplate and castle nut from Lockhart Tactical
Ergo grip
Taccom buffer and reduced spring
Radian Raptor LT
DPMS LPK
DPMS mil spec trigger (for now)
Phase 5 extended bolt catch
Brownells Nitride low mass BCG
TNA Canada flag dust cover
TNA match 18.6" 223 wylde barrel w/ 1 in 7 twist and rifle length gas
Odin clamp on adjustable gas block
Odin O2 Lite Mlok handguard
Precision Armament brake

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The T9 is not really needed to hold the trigger pack in place, as the safety does that. Also, if you over tighten the T9 screw it can make the safety too stiff to operate.
We have not found any parts that would not install on the receiver. We used DPMS LPK and dust cover assemblies, Geissele triggers, and ADM hanguards.
There was an interference problem with the bolt catch that caused it to not hold open on the last shot. We identified the fix here: https://www.canadiangunnutz.com/forum/showthread.php/1641027-Maccabee-Defense-SLR-Info-site
Follow on receivers seem to have been altered to avoid this issue (look for a small bevel on the upper receiver rail just above where the bolt catch would sit)
 
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Turns out that the thread insert For the retention screw tread was out just a fraction, gental tap with a mallet did the trick
 
I didn't have a problem with the bolt catch roll pin; I pinched the end down a bit so it would guide itself in a bit easier, but it seemed to go in fine. My safety is tight as all ####, but I ordered a new (Nicer) one anyways, I'll try loosening the screw that holds down the trigger box and see if that frees it up at all. If not, I'll rig up a little tool for my die grinder and open the receiver/trigger box a bit with some scotch brite. My magwell doesn't like my standard c products LAR mags, but my e-lander steel mags and MFT polymer mags both drop free. They seat properly after modifying the radius on the remaining magwell corners on the upper; they had a noticeably bigger radius than the lower, and when you assemble both halves you can see a little flat where the upper/lower meet that causes interference. MDI definitely had issues machining the corners of the magwells. Ordered a couple more MFT mags and some couplers from gs designs, and I should be good to go for 3 gun :)

Also found out that the BAD lever wouldn't work, so I ordered a Phase 5 EBR V3. Anybody wanna buy a BAD lever? Lol.
 
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I switched the trigger packs between two sets and now one safety works normally and the other is stiff before both were really stiff. I guess some difference in the tolerances?
 
Anyone else having issues with their retention screw coming loose. I've not ever over tightened the bolt, but hand tightened til very snug. Every 100 rounds or less, especially when double tapping ends up loosening to the screw and my upper from the lower.

Is there an alternative detent being worked on?
 
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