NO M4 feedramps?

[newt91guy]

Trying to figure out why a modern A.R. 15 type weapon with a short stroke piston system and conceivably shorter dwell times does not have extended M4 style feed ramps...

Wondering if that’s why YouTube channels MAC and Michel bell both had rounds pushed into casings !

Thoughts?

[apex]

Probably because the 205th figures they're not necessary. M4 feedramps were needed on the M4 carbines due to the higher cycling rate causing feed issues. T91s don't have as high fire rate as M4s, but I agree having them would be nice. All the free Western sources site a cycling rate of around 800 for T91s, but who knows if this is actually accurate. Michael Bell's unsuppressed upper ran around 500.


To the point of both youtubers you've listed, in both cases they were using open tip ammunition when the malfunction occurred. Even though MAC says he's using M193 ball earlier in the video, when zoomed in post-failure you can clearly see he is using open tip ammo (see attached). Michael Bell's malfunction was also due to using open-tip ammo.

mac_t91_open_tip1.JPG

Personally I have also had this exact same malfunction when using hollow points. I suspect hollow point and open tip rounds are just ever so slightly too short to properly engage the feed ramps, but having M4 ramps would solve this.

Moral of the story: feed your Wolf FMJ.

[Brok3n]

My early release Wolf A1 upper also experienced a couple of nose dives using Federal M193 ammo although I attributed as a magazine issue. It was also using the same tan "Surefeed" magazine that MAC was using. I sold all those off after since I was experiencing issues with them across multiple rifles.

[newt91guy]

Amazing info and investigation work. Thanks so much man!
It does make me cringe knowing m4 feedramps would likely smooth feeding and yet we can’t have them with dremeling them in ourselves

Thanks again

Probably because the 205th figures they're not necessary. M4 feedramps were needed on the M4 carbines due to the higher cycling rate causing feed issues. T91s don't have as high fire rate as M4s, but I agree having them would be nice. All the free Western sources site a cycling rate of around 800 for T91s, but who knows if this is actually accurate. Michael Bell's unsuppressed upper ran around 500.


To the point of both youtubers you've listed, in both cases they were using open tip ammunition when the malfunction occurred. Even though MAC says he's using M193 ball earlier in the video, when zoomed in post-failure you can clearly see he is using open tip ammo (see attached). Michael Bell's malfunction was also due to using open-tip ammo.
mac_t91_open_tip1.JPG

Personally I have also had this exact same malfunction when using hollow points. I suspect hollow point and open tip rounds are just ever so slightly too short to properly engage the feed ramps, but having M4 ramps would solve this.

Moral of the story: feed your Wolf FMJ.

[apex]

Amazing info and investigation work. Thanks so much man!
It does make me cringe knowing m4 feedramps would likely smooth feeding and yet we can’t have them with dremeling them in ourselves

Thanks again

I mean you could pull the barrel and piston assembly from the upper, remove the barrel extension, install one with M4 feed ramps, re-time and properly headspace it, then throw the re-finished assembly into an AR-15 upper receiver with M4 cutouts... if you're a trained gunsmith. As seen here it can be done: viewtopic.php?p=1536#p1536
I have no idea if this will lead to any extra/premature wear from using a piston system in a DI receiver though.

[JTM20]

The Canadian C8 carbine also lacks M4 feed ramps. Apparently they solved feeding issues by using a heavy buffer.

https://smallarmssolutions.com/home/the ... ram-part-2

[apex]

The Canadian C8 carbine also lacks M4 feed ramps. Apparently they solved feeding issues by using a heavy buffer.

https://smallarmssolutions.com/home/the ... ram-part-2

I'd be curious to know what the actual weight of the buffer they're running is.
On a less serious note, I wonder if they also lube it with syrup

[apex]

Bit of an update to my previous post on the T91 fire rate, judging from this video it would appear the reported fire rate of around 800 is indeed correct.