Feed ramps

[A5BLASTER]

Ok sitting here thinking forward to blending and polishing a couple of feed ramps this Friday and got to thinking.

Feed ramps on the extention and upper were designed for the 223/556 round could the grendel benefit from a different angle and or size of feed ramps?

[Kswhitetails]

Nope. Work as they should. Just make sure that the break between the upper and extension favors the receiver, and they should feed like a champ.

The extension should be forward of the edge of the receiver if there is any break in the two. You want the bullet tip to "jump" the gap.

There is a slight set back between the receiver and the extension here, this is what you want to see. There is more of a gap than it looks, the cerakote makes it hard to see as well as I'd hoped.

Untitled by ., on Flickr

[ricsmall]

I’ve often wondered about this. Check out Olympic arms feed ramps on their 7.62x39. They fed flawlessly for me. Didn’t check brass for scratches but it works well. I’ll see if I can find a pic

http://i150.photobucket.com/albums/s95/M...9_ramp.jpg

[LRRPF52]

Grendel benefits from M4 ramps and receiver cut, which is already present on most uppers and extensions nowadays.

Most people getting into ARs don't even know there was the original M16 upper and extension.

The Colt 727 (M16A2 Carbine) introduced the lowered feed ramps to deal with full auto and M855 as a band-aid for excess cyclic rate.

You don't really need it in 5.56 AR15s, but it is helpful for feeding Grendel. I seem to remember Bill A. commenting on it way back.

[A5BLASTER]

This is why I asked I tryed the old Google fuu and came up empty just wanted to see if Bill or anybody had done any research on this topic.

What got me think about it was I remembered a jam or two I had while either slow riding the bolt closed or somehow the charging handle got snaged for a sec on something.

The resulting jam had the bullet squarely in both edges of the ramp it was going in on.

So I'm sitting here thinking since we are useing 6.5 mm bullets instead of 223/556 bullets could the grendel due with a lil less material in the middle of the extentions feed ramps.

To me it seems to make sense but that's just me and my thinking.

Not planning on doing anything like that was just wondering if anyone had done thinking on that idea.

And yes my rifles run fine, just need to get to polishing the ramps.

[A5BLASTER]

Nope. Work as they should. Just make sure that the break between the upper and extension favors the receiver, and they should feed like a champ.

The extension should be forward of the edge of the receiver if there is any break in the two. You want the bullet tip to "jump" the gap.

There is a slight set back between the receiver and the extension here, this is what you want to see. There is more of a gap than it looks, the cerakote makes it hard to see as well as I'd hoped.

Untitled by ., on Flickr

Yea all mine look like that and understand that's how they should look.

Guess I didn't word my opening post correctly.

What I was meaning is did anyone research are try to develop a wider feed ramp area in the barrels extention dinking the grendel with its much wider bullet profile compared too 223/556.

Figured Bill or somebody had but Google fuu is not strong with me tonight couldn't find any intel.

[LRRPF52]

The problem is if you let a cartridge with really sharp, secant ogive bullets feed too low through the feed ramps, the meplat of the bullet hits the breech and not the chamfer or chamber.

With the big fat bores, not a problem, and some have even eliminated the center lug of the extension to accommodate their massive frontal area and path to the chamber.

With Grendel, you want as much lift as you can get into presentation without the ogive riding in too low.

This also drives the dimensions of feed ramps, and upper-to-lower receiver fit.

[A5BLASTER]

Thank you for the Intel sir.