re: Official AR-15 thread

Accu-wedge. I think I bought several bags of 6 a couple years ago and still running on them.

You can also get a 5mm rubber washer and put it in the front pin lock in the upper receiver. I use on several of my AR’s.

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Haven't shot the gun or anything yet, but one thing I'd love to improve is the play between the upper and lower. I realize this is cheap and have mixed upper and lower receivers, so it's expected to not be the greatest. But are there options to reduce that loose fit. I've seen where people will put ear plugs by the rear takedown pin, etc.. Is there a more legitimate option? I see some lowers have an adjustable set screw to take up the slack, but don't have that. I've seen some rubber pieces in videos, but have no clue what it's called to search for it.

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How much play is there actually? Reason why I ask is because, contrary to what some AR "experts" will state, play between the upper and lower receivers will have virtually no impact on accuracy or durability. I've been issued M16's and M4's for over two decades in the Army and even the sloppiest, A1-rebuilt-to-an-A2 M16 shot as well as a brand new M16A2 as long as I was doing my part. I know it's disconcerting to those not familiar with these rifles but I'd put up with a little slop long before putting pieces on rubber or plastic in the receiver. Those pieces deteriorate and break apart eventually, and then you have debris with an easy shot to your trigger group which is exactly where you do not want such pieces to wind up. Since this is your first rifle build, you need to shoot it and get some heat and vibration in it then check everything you've done to see that it retained proper torque. Loose barrel nut, loose hand guards, sights, etc. will affect shot groups more than the upper/lower fit.

I have a 10.5" 5.56 build that was a single shot. Tried everything that you did and I finally drilled the gas port on the barrel and that fixed it.

I don't remember the sizes. It was a small drill bit and you can find with an easy google search.

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Tried everything that you did and I finally drilled the gas port on the barrel and that fixed it.

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yeah, Sprinco's site actually says that's ultimately what's required:

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Reduced Power Buffer Spring. We collaborated with two prominent commercial ammunition manufacturers and two prominent gunsmiths to arrive at the design for the Yellow spring. It’s approximately 20% lighter than the White spring, and was the consensus choice out of 4 different evaluation samples provided to all parties. They all added in their final evaluations that if a particular gun needed a lighter spring, that the gas port should be enlarged for overall reliability. The Yellow spring is also appropriate for with low power SRTA training or SIMS Rounds for training operations. Color coded YELLOW.

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instead of buying a lighter spring, i've also read you could simply cut a coil off a carbine spring and it's the same thing.

You have an adjustable gas block on it so making the port larger won’t hurt anything

What recommendations for an affordable (sub $100?) Flashlights are there? Lower the profile, the better.

Finished my first build a couple weeks ago and now have the bug. Just got another lower to build up. Going to be a 300 blackout SBR. Trying to settle on a barrel to start the Form 1 process. Looking for a 7.5-9" barrel and will suppress. Reading to get a 1:5 twist for the heavy subsonic load. Ita not a money is no object scenario, but not skimping on this build where it matters. What would you be looking at?

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I have a 7.5 faxon 1:5. This size does limit handguard selection though.

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just recently bought this barrel. here's the handguard i bought...

https://www.opticsplanet.com/arms-republic-rs-ar-15-m-lok-handguard.html


the 7" length version





here it is with my Aero Precision Lahar-30 / SiCo ASR Mount

Need a non adjustable gas block that is actually .750, any suggestions?