AR15 Upper swap

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x_wrench

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I am thinking about picking up a 16" upper because my daughter struggles holding up my heavy barreled 20" rifle. it uses a rifle length gas system, and I know that a 16" upper will have either a carbine or mid length das system. what else will I need to buy to make this work? also, is it a bad idea to run the same BCG in both uppers?
 
There are a few different answers to these questions.

Are you switching cartridges?

My answers are

Don’t worry about the gas system now. It can and probably will work. If it doesn’t then just go from there.

The BCG can work but I generally frown upon using the same BOLT in different barrels.

Many answers have good reason behind them and others may have nothing behind them other than one isolated incident or flat out superstition.
 
+1 on using the same BCGs... Possible headspace and wear differences... I may get hammered but Bear Creek Arsenal has complete uppers (including BCGs) starting at under $250 delivered on sale... I'm not affiliated with them but I've purchased 5 and have not been disappointed... Not "top tiered" but accurate and useable... The Walmart of uppers...lol
 
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+1 on using the same BCGs... Possible headspace and wear differences... I may get hammered but Bear Creek Arsenal has complete uppers (including BCGs) starting at under $250 delivered on sale... I'm not affiliated with them but I've purchased 5 and have not been disappointed... Not "top tiered" but accurate and useable... The Walmart of uppers...lol

I was thinking Palmetto State Armory but your post got me to go look. Bear Creek has some very reasonable deals going right now. I've never owned a Bear Creek Armory upper or rifle but a friend used one of their uppers for an AR-10 build. I have shot his rifle. I like it.
 
I was thinking Palmetto State Armory but your post got me to go look. Bear Creek has some very reasonable deals going right now. I've never owned a Bear Creek Armory upper or rifle but a friend used one of their uppers for an AR-10 build. I have shot his rifle. I like it.
I've not used any Bear Creek parts either (I'm in no way affiliated :)), but I do know that with guns in general and AR's in particular, you often get what you pay for, up to a certain point. For a range toy, or for the thing that most folks use their AR's for (leaning in the corner of a closet) quality is basically irrelevant. Have to determine what you're buying it for.
 
"Are you switching cartridges?"
no, staying with 5.56x45.
I WANT to keep it relatively simple. pull pins, swap out uppers, and push pins, shoot.
Get a complete upper, with bcg, and you're good to go. :)
Just keep in mind that the recoil impulse is a little more pronounced with the shorter gas tube, also the shorter barrels often have a different twist rate, tuned for 62gr. bullets usually, and that upper may like different ammo.
 
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is it a bad idea to run the same BCG in both uppers?
For my 2¢, just get a "complete" upper, so, you get a BCG with the upper.

If possible stick with like-for-like, so get the same rifling twist rate. Again, for my 2¢, match the fore ends, too--free float v. delta ring; with or without FST, etc. I find you'll wind up with sight to match, too, rather than having dismount one to the other. That really makes it plug-n-play, pull the pins and just swap.

Now, in all fairness, ask the question on arfcom, and there will be a flamewar on buffer weights and gas lengths. To my mind, barring large changes in caliber used, is just arguing how to go from 99.9% equal to 99.95%. That, it's really the same number of angels on the pin head, and they are arguing about how many cherubim you can get in too.

Now, fair warning--having a upper in the safe can cause lowers to appear. That's usually where customization to a specific use or user occurs.
 
FWIW, I just bought a 'kit' from Palmetto... everything except the lower itself... for $400 shipped. Spend another $50 or $60 or so on a stripped lower... and you can have another complete rifle. Having a complete rifle is a better option than swapping uppers, etc. I was surprised... the upper was completely assembled, I expected it to arrive as parts. A good cleaning, a once over on a few things... and off I went. 16" mid-length upper, MOE furniture.... nice rifle.

If you still want to just go the upper route, I would buy one with the complete BCG... don't swap bolts. I always recommend a mid-length gas system on 16" barrels... just my .02 worth, although I'll say most carbine length systems work well enough.

Having said that... here is a Daily Deal at Palmetto on a carbine-length... at $270 with BCG???

https://palmettostatearmory.com/ble...ato-1-8-phosphate-classic-upper-w-bcg-ch.html

Rifle on the left is the Palmetto kit...

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https://palmettostatearmory.com/psa...-1-7-nitride-moe-odg-rifle-kit-516444601.html
 
The gas system and the buffer system are fairly independent. You can run a rifle length gas system on carbine buffer or carbine or pistol length gas system on a rifle buffer. Within reason these two are fairly independent.

I am running a 22-inch rifle length 30RAR on a standard carbine receiver extension spring and standard weight buffer.

Having a properly regulated gas system (ie gas port size) is most important.
 
You'll have much better results with 11.5".
Technically this would be illegal without an SBR tax stamp since his lower has already been assembled as a rifle.
I know, I know, no one would know.....but they would still need a "brace," and ATF has been rumbling about cracking down on those as well lately.
The 11 inchers (and shorter) start to get ridiculously loud too, without a can anyway.
 
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And the tread drift has begun. The OP is specifically asking about a 16" upper.

I am thinking about picking up a 16" upper because my daughter struggles holding up my heavy barreled 20" rifle

@x_wrench You will be better off buying a complete 16" upper that comes with its own bolt carrier group. While it is normally okay to swap bolts, it is not recommended since issues can pop up.

I suggest watching Palmetto State Armory. Their Black Friday deals have already started. While they maybe more expensive than Bear Creek Arsenal, You will get a better quality upper along with better customer service.
 
FWIW, I just bought a 'kit' from Palmetto... everything except the lower itself... for $400 shipped. Spend another $50 or $60 or so on a stripped lower... and you can have another complete rifle. Having a complete rifle is a better option than swapping uppers, etc. I was surprised... the upper was completely assembled, I expected it to arrive as parts. A good cleaning, a once over on a few things... and off I went. 16" mid-length upper, MOE furniture.... nice rifle.

If you still want to just go the upper route, I would buy one with the complete BCG... don't swap bolts. I always recommend a mid-length gas system on 16" barrels... just my .02 worth, although I'll say most carbine length systems work well enough.

Having said that... here is a Daily Deal at Palmetto on a carbine-length... at $270 with BCG???

https://palmettostatearmory.com/ble...ato-1-8-phosphate-classic-upper-w-bcg-ch.html

Rifle on the left is the Palmetto kit...

View attachment 1116219

https://palmettostatearmory.com/psa...-1-7-nitride-moe-odg-rifle-kit-516444601.html

I like PSA products & own one of their AR's & one of their Dagger pistols. Bear Creek has a complete rifle for under $400.223 Wylde, 16” Parkerized M4|New MLOK|Rifle (bearcreekarsenal.com) or just the upper for a little over $200. 5.56 NATO, 16” Parkerized M4|New Handguard (Spiral Flash Hider) Upper (bearcreekarsenal.com) They also have a 10% off promotion on their site.

I am not saying what the OP should buy. That is up to them but there are affordable options out there. I would suggest taking their time & doing their research.
 
Let’s see… just how complicated can we make the simple answers of “don’t overthink it, gas system length and buffer design aren’t interdependent. Two pins and you’re done”. And “sharing BCG’s is fine, but it sucks to swap, so buy another BCG.”
 
Your best bet is shopping PSA and getting a complete upper w/ BCG that you like, then upgrading optics and such as funds become available.
 
Del-ton has a sale right now. They are very good quality. I would recommend Mid-length gas system. I had the same issue.
 
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