The upper receiver itself is easy; something of solid, known quality but not out of the ballpark: Aero, BCM, Rainier
I don’t know if Ballistic Advantage barrels still carry the accuracy they were known for originally. Others might be able to chime in there
I prefer a set screw adjustable gas block so you can fine tune how much gas is going through the system. You can get a smooth shooting rifle this way.
I started off the match/precision road with a barrel similar to this and it shot extremely well for me:
18” Rainier Arms select barrel (rifle gas)
- Stainless Steel Match Grade Blank
- Twist: 1:7
- Thread Pitch: 1/2 X 28
- .750 Gas Block Seat
- 5.56 NATO Chamber
- 5 groove polygonal rifling
- M4 Feed Ramps
- Proprietary Contour
- Nitride Finish
Rainier Arms Select 5.56 NATO Barrel Many have asked us to build a barrel with the same workmanship as our Match barrels while keeping it more affordable. We are able to reach our goal by sourcing a very high end barrel blank at an affordable price. We st
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The other main thing would be the rail itself. I really like how solid a Geissele Mk14rail is but they’re not cheap.
Another solid one would be the 15” Aero R-One. The longer the barrel, the longer the rail you typically will want
Aero Precision AR-15 Atlas R-ONE M-LOK Handguard - 15\
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RA BCG (I’ve got a few of these and like them so I threw it in but obviously this part can be preference for coating, brand etc)
Rainier Arms AR-15 Precision Match Grade BCG - Nitride The Rainier Arms Precision Match Grade Phosphate BCG - 5.56 Nitride is machined and finished to a higher standard to meet and exceed all Mil Spec. It is machined using the most precise equipment in th
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Superlative Arms block & tube
Superlative Arms Adjustable Gas Block Bleed Off (Solid) - Melonite The Superlative Arms Patented “Bleed Off”, direct impingement, gas block for the AR-15/AR-10/LR-308 platform adjusts the gas flow by bleeding the gas out of the front of the block instead
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And finally muzzle device. If you run a can, you may have that in mind already but if not, you may want a muzzle device that helps reduce recoil and muzzle rise in order to assist with accurate follow up shots
I kinda broke the budget but I don’t think you’d be left wanting down the road with the larger main components in here and nothing is more expensive than trying to build cheap if you’ve got to spend the money redoing something. And again these aren’t the end all be all selections, it’s more about WHY the parts are decided upon.