450Bushmaster.net

New to the forum and building a 450 BM upper. Looking at stripper uppers I was leaning towards the Areo XL as I have several other Aero uppers as well as lowers and appreciate the quality. The spec sheet of the XL upper says it has M4 feed ramps which doesn't make a lot of sense to me for the 450. Will this work without modification? I want to shoot Hornady 250 XTP's and they aren't a pointy bullet.

TIA, Rod.

It should work, might depend on the type of feed ramps the barrel has.

the situation where i understand that M4 vs Rifle cut feed ramps in receivers/barrel extensions really becomes a problem is with small pointy bullets that can/may get hung up in the gap created where the two meet in a bad combo.


here's an old image thats been around on the web for a while showing what is and isnt ok in that regard.







with the size/shape of bullets we use in this caliber - combined with the fact that our cartridges are single stack in the mag and not staggered like smaller bottleneck cartridges are - i dont think having or not having m4 ramps cut into the upper will be wildly problematic either way, as long as your barrel extension itself is cut properly, as the bullet tip isnt going to align with either of the m4 cut grooves in the receiver.

hth

plant_one wrote:the situation where i understand that M4 vs Rifle cut feed ramps in receivers/barrel extensions really becomes a problem is with small pointy bullets that can/may get hung up in the gap created where the two meet in a bad combo.


here's an old image thats been around on the web for a while showing what is and isnt ok in that regard.

https://i296.photobucket.com/albums/mm198/WeberSteve/4cb400b4.jpg





with the size/shape of bullets we use in this caliber - combined with the fact that our cartridges are single stack in the mag and not staggered like smaller bottleneck cartridges are - i dont think having or not having m4 ramps cut into the upper will be wildly problematic either way, as long as your barrel extension itself is cut properly, as the bullet tip isnt going to align with either of the m4 cut grooves in the receiver.

hth

+1

Hoot

I’ve used Aero XL upper receivers on both of my 450 builds and I’m extremely happy with them.

303hunter wrote:I’ve used Aero XL upper receivers on both of my 450 builds and I’m extremely happy with them.

Thank you, that is the answer I was hoping for.

As the 450 is a center feed, TWO feed ramps is actually counter intuitive. A single wide ramp (polishing out middle) seems to be best for reliable feeding.

CW

https://www.google.com/search?q=450+Bushmaster+feed+ramp.pic&ie=UTF-8&oe=UTF-8&hl=en-us&client=safari#imgrc=3pa61n_zAHgayM

cwlongshot wrote:As the 450 is a center feed, TWO feed ramps is actually counter intuitive. A single wide ramp (polishing out middle) seems to be best for reliable feeding.

CW

https://www.google.com/search?q=450+Bus ... 1n_zAHgayM

That was my thought as well, which made it all the more curious why the Aero XL would have m4 feed ramps. But it has been noted that it works.

My buddy has one and I have a Bear Creek bbl. both of ours are a single ramp.

CW