I installed a barrel into my Mega Maten upper today but was surprised to see that the barrel has feed ramps while the upper doesn't.

I have read about numerous 6.5 CM barrel installs in the Mega upper w/o any mention of this mismatch.

This is a non-starter right?



Thanks for your advice,
Henryrifle

quote:

Originally posted by henryrifle:
This is a non-starter right?

It should work just fine. It's the other way that's a non-starter.

Yeah you are GTG.

Thank you both. Still looks wrong-ish.

Henryrifle

Where did you get your 6.5 CM barrel?

I bought an AR-10 stripped lower and two stripped uppers a few years ago. I built one into a .308 and have always meant to build the second into a 6.5 CM but haven't gotten around to it.

Fulton Armory generally has both Criterion and and Krieger 6.5 barrels in stock. I've purchased two Krieger AR barrels from Fulton.

Thanks!

I did get it from Fulton Armory. fritz turned me on to Fulton Armory about a year ago. It was a very good recommendation. Thank you, fritz.

If you order the bolt and barrel at the same time they'll headspace it for you. I wanted the target gray finish which they were out of. I called them and they were able to refinish one of the stainless barrels they had in stock.

I spoke with them and ordered on a Monday and had the barrel, bolt carrier group and adjustable gas block on Thursday!

I shot it this weekend following the break-in procedure. I only had 1 box of ammo as this project came together much faster than anticipated. The last five shots at 100 yards measured .7" using Norma Scirocco II ammo. It sure looks promising. By the way, I picked that ammo as its muzzle velocity was under 2800 fps. I had no expectations of performance.

Henryrifle

For follow-up and conclusion:

Initially it seemed like there would be no feeding issues but, as soon as I switched away from factory plastic or polymer tipped bullets to hand loaded HPBT Scenars and AR Hybrids, feeding troubles became the norm. After smashing several rounds into the upper I decided that I didn't have much to loose. I ground and polished my own feed ramps into the lower and there have been no further problems. This was not hard to do.

I used a Dremel with a small followed by medium conical shaped grinding stone and followed up with a small cloth-type polishing wheel and compound. The sides are not perfectly symmetrical and one looks more highly polished than the other but, so far, it functions without failure with both hand loads mentioned above. I am taking that as a sign to quit while I am ahead.



Chamber is filthy in this pic.

Henryrifle

You need to be aware that raw aluminum is MUCH MUCH softer than Anodized or Cerracoated Aluminum. I would expect that in time you'll find the area you machined becomes gouged enough that your feed issues will re-appear. Good news is that ne uppers aren't hugely expensive so I would suggest that you put a new upper with M4 feed ramps on your future shopping list.

BTW, Gibbz Arms side charging uppers are rather expensive but having built a precision AR in 223 Wylde using a Shilen barrel I can state the fit between upper and barrel extension was the most perfect fit I've ever encountered. The fit was tight enough it would push together by hand but a few taps with an 8 ounce nylon hammer seated the barrel in the upper perfectly. I'll also tell you that I was so impressed with the mounting system for the Gibbz handguards that I've used their handguards on all 3 of my builds and a co-worker who I turned on to Gibbz now uses their handguards on all his new builds.