AR-10 Question

[In-Yo-Grill]

Been a while since I've posted so you know...be gentle. lol

I have a stock Aero Precision AR-10 with a 16" barrel. I wanted to buy an 18" or 20" upper (same brand) to swap out with the lower. Want to use the longer barrel for hunting.

I was told that there may be an issue with doing a direct swap from the stock 16" to an 18-20" and would require new buffer and springs. Can someone educate me as to how I could make with same lower work with the two different sized uppers?

[JDH875]

I don't believe that is true. You should be able to swap uppers on that lower without an issue. Now that being stated, all the AR-10s I have worked with have cycling issues at some point. I have never owned or shot a Aero Precision so I don't know if they come with an adjustable gas block which might need to be adjusted but I even doubt that. And without sounding condescending, I highly recommend calling Aero Precision. I am willing to bet they would be able to answer your questions better than anyone else. Good Luck!

[scott123456789]

Shouldn’t change your buffer need. However 2” of barrel would be very insignificant

[Lsube0555]

Changing uppers same caliber will have nothing to do with buffer and spring. Only thing I could see if you went from a pistol length with a heavy buffer to rifle length might would require default weight buffer. On the same token if you staying 308 you’re not going to gain anything by going from 16 to 18 or 20” besides wasting money. I doubt your math shooting 1000 yards with it. Inside of 500yrds you’re not going to notice anything with a couple extra inches of barrel just my opinion. Save your money and upgrade other stuff or just change the barrel no need to buy a whole new upper

[In-Yo-Grill]

I don't believe that is true. You should be able to swap uppers on that lower without an issue. Now that being stated, all the AR-10s I have worked with have cycling issues at some point. I have never owned or shot a Aero Precision so I don't know if they come with an adjustable gas block which might need to be adjusted but I even doubt that. And without sounding condescending, I highly recommend calling Aero Precision. I am willing to bet they would be able to answer your questions better than anyone else. Good Luck!

That was the first thing I did. The rep told me that you can't just "swap" different length uppers and expect the rifle to perform the same. I can see the gas block needing to be adjusted.

Shouldn’t change your buffer need. However 2” of barrel would be very insignificant

My wife would disagree...

Changing uppers same caliber will have nothing to do with buffer and spring. Only thing I could see if you went from a pistol length with a heavy buffer to rifle length might would require default weight buffer. On the same token if you staying 308 you’re not going to gain anything by going from 16 to 18 or 20” besides wasting money. I doubt your math shooting 1000 yards with it. Inside of 500yrds you’re not going to notice anything with a couple extra inches of barrel just my opinion. Save your money and upgrade other stuff or just change the barrel no need to buy a whole new upper

Doesn't a longer barrel mean a longer burn on the powder giving the bullet more velocity? My ultimate goal was to have a multipurpose .308. The short 16" barrel for...well, whatever, and the longer 18"-20" barrel for hunting. Or longer range "fun" shooting.

The 18" Aero Precision barrel I'm looking at is a stainless fluted barrel. Supposed to be superior quality over their stock 16". Believe me, I'm not trying to justify a purchase. Just trying to get more educated so that I can make a better decision.

Thanks to everyone who has responded. Please don't be shy and keep this conversation going. I honestly don't know *** I'm talking about when it comes to barrels and ballistics so you won't hurt my feelings by crushing my theories...lol

[imyomama]

if aero sells 16" 18" and 20" ask them if the buffer and spring are the same.. i bet they are!
most likely they just drill the barrel port hole to proper size to cycle for whatever length barrel so everything else stays the same.

from 20" to 16" , count losing 50ft/s per inch ... so 200fps slower from a 16" than a 20 ..

[Chase4556]

As others have said, the difference between a 16 and 20 inch barrel is pretty much negligible unless you are shooting long range. No animal will get hit with a ~200fps slower bullet and shrug it off.

Even if you take it to the range to shoot 500+ for fun, it will still do it. Might have issues at 700+, but I don’t know the specifics on when it will start going transonic and all the technical stuff that guys who shoot 308 out to 1000 have to deal with.

[txhunter2]

I have an aero 16 and 18. One was mid length and one rifle length Both were overgassed. I tried switching to a heavier buffer on 1 with little to no difference. I installed a superlative arms gas block on both and it is cycling and the ejection pattern are now both where they need to be after adjusting each.

I highly recommend this. It was easy to open or close the gas block even with the handguard on them.

[Lsube0555]

100-200 fps gonna make a difference is wide of 4-500 yards? Enough to justify buying a whole upper for that? You could make a case for upgraded barrel for accuracy issues maybe. But ultimately it’s up to you. Original question answer you will not need to change anything on the lower. A 16” upper that cycles properly will run same upper in 18” nothing changes between uppers. Only time you need to change buffers are if maybe running a pistol length upper and bcg is cycling way to fast. But most can get away with just having a adjustable gas block

[LWD]

How far you shooting? How much velocity you looking for? 16" barrel in .308 should stay supersonic to 600 yards.

[okiepighunter]

i had a 20" BA barrel that wasnt threaded had gunsmith cut 3" off and thread it lost about 80 fps didnt effect performance at all

[Ham]

I have a AP in 308 carbine. No adjustable gas block.

I use Odin Works adjustable buffer and different spring weights from SprinCo to adjust b/t barrels/loads.