polymer ar 15 upper receiver

[1Snowball]

Poly uppers?

[Merc1138]

Poly uppers?

Technically, the upper receiver isn't subject to much either, kind of like the lower receiver. You have to remember that most of everything is being contained within the bolt and barrel extension while it's closed. Other than some gas coming back through the BCG, and the BCG itself sliding back and forth there isn't much going on.

The problem lies in replacing one material(aluminum) with another material("polymer", aka plastic), and not changing the actual design of the item(the upper receiver) to account for strength differences in materials that can allow various thicknesses in say... the walls of the upper. Look at the broken plastic lowers, same problem. They changed the material, but didn't change the actual dimensions of the lower to account for the difference in strength.

Now a vulcan poly upper, that's just asking for problems. For all we know the thing is made out of melted down grocery bags, and who knows whether or not it even conforms to any sort of standard upper receiver dimensions to even allow a barrel installation, let alone actual use.

It's like the difference between a plastic tonka toy that a toddler likely isn't going to destroy without seriously trying, and a dollar store equivalent that just falls apart the moment they set it on the carpet.

[1Snowball]

Technically, the upper receiver isn't subject to much either, kind of like the lower receiver. You have to remember that most of everything is being contained within the bolt and barrel extension while it's closed. Other than some gas coming back through the BCG, and the BCG itself sliding back and forth there isn't much going on.



The problem lies in replacing one material(aluminum) with another material("polymer", aka plastic), and not changing the actual design of the item(the upper receiver) to account for strength differences in materials that can allow various thicknesses in say... the walls of the upper. Look at the broken plastic lowers, same problem. They changed the material, but didn't change the actual dimensions of the lower to account for the difference in strength.



Now a vulcan poly upper, that's just asking for problems. For all we know the thing is made out of melted down grocery bags, and who knows whether or not it even conforms to any sort of standard upper receiver dimensions to even allow a barrel installation, let alone actual use.



It's like the difference between a plastic tonka toy that a toddler likely isn't going to destroy without seriously trying, and a dollar store equivalent that just falls apart the moment they set it on the carpet.

Don't forget to mention heat transfer from the barrel to the upper and the hot hot gas from the gas tube. Have not come across any "cheap" polymer that stands up well to thermal degradation. I Think ppl who are doing poly lower/upper are just a little bit nuts IMHO.

[Merc1138]

Don't forget to mention heat transfer from the barrel to the upper and the hot hot gas from the gas tube. Have not come across any "cheap" polymer that stands up well to thermal degradation. I Think ppl who are doing poly lower/upper are just a little bit nuts IMHO.

Again, that's an issue of not bothering to re-design the part to account for the material difference. Simply using a piston instead of the traditional DI avoids a lot of issues. Even with an aluminum upper you can shoot fast enough(if you have enough ammo) to melt the gas tube and possibly even have plastic handguards catch fire. I'd honestly be more concerned about the weight of the barrel clamped around the front of the receiver and how thin that polymer area between those threads and the receiver is, un conjunction with the bolt carrier making contact with the receiever, than the typical joe schmoe melting components at the range(it's not like we're talking about things being issued to the military here).

But with all that said, it's not like vulcan bothered to redesign anything to make up for the difference in materials, and their total **** reputation would make it not worthwhile even if they had.

[1Snowball]

You can change the design all you want but you'll never get the same material properties of AL out of polymer.

[Marquand]

Yeah...this strikes me as a marginal design being very poorly executed. If a reputable company with a tradition of quality tried it, I'd be skeptical. But Vulcan's Flintstonian build ethic? I'll pass.

[Merc1138]

You can change the design all you want but you'll never get the same material properties of AL out of polymer.

And this is why it's so nauseating to see people using the word "polymer". There are many, many types of polymer and materials added to polymer, that do a wide variety of things. It's not 1960, and using polymer works in many situations without being flimsy like some green army men that melted to the radiator in the hallway. If manufacturers would quit going the polymer route to be cheap, and instead to save weight, someone might eventually make something worthwhile.

[1CavScout]

I have a Bushmaster Polymer Upper that I bought back in 2004. It's sitting in my safe right now, but I put thousands of rounds through it without any issues. Just FYI...

[klewan]

I have a Bushmaster Polymer Upper that I bought back in 2004. It's sitting in my safe right now, but I put thousands of rounds through it without any issues. Just FYI...

What does the area around the bolt carrier look like? Lots of heat back there, I would guess it would be scarred up..

[1CavScout]

What does the area around the bolt carrier look like? Lots of heat back there, I would guess it would be scarred up..

it's actually not. The wear looks similar to aluminum uppers I have.

[klewan]

it's actually not. The wear looks similar to aluminum uppers I have.

So why all the hate on plastic? AR's, the barrel extension takes all the load. And if the heat isn't screwing up the bolt carrier tunnel, why all the pissing and moaning? It's Blackthorne! Everything they sell is suspect.

[ElvenSoul]

I have 2 Carbon Uppers that have been holding up just fine

[JDay]

I wouldn't use polymer for anything more powerful than airsoft.

Sent from my LG G3

[klewan]

I wouldn't use polymer for anything more powerful than airsoft.

Sent from my LG G3

Well given what other peeps have said about their polymer uppers, you just don't have a clue. They obviously work.

[ElvenSoul]

2 makes of Polymer Lowers that work

http://www.tnarmsco.com/receivers/

http://www.gwacsarmory.com/lower-receivers-ar-15/