Another failure to chamber thread.... help please

[toolsofthetrade]

ok here are the specs.
Mega upper, BHW barrel .264lbc
brand new build here are pics of chamber


the mags are C-Products
the problem is the right hand round is jamming as seen in these photos, this is 1st round right hand side of mag. does it ALL the time.


the ammo is some I bought actually just for the brass, it is AA and lapua brass, reloaded with unknown primer (brass colored), 31.5gr of BLC(2) 120gr unknown spitzer bullet loaded to a COAL of 2.127" Brass looks to be 1.518" Velocity of 2600fps, bullets were loose in the neck when i got them, so i put a slight crimp on them to hold them at length. All show pressure signs, primers flattened, 3 pierced primers some primers showing a slight backing out. (only fired 7 rounds)

So is my jamming problem potentially ammo related? or is it something else?

[ss355]

Do you have the chambering issue with factory ammo? My first inclination is to say that it's the ammo, not the gun.

[toolsofthetrade]

its not a chambering issue as in athe ammo I don't believe, because if that was the case it wouldn't chamber from either side of the mag, this only happens on the right side of the mag.

[Rootshot]

Visually, this looks exactly the same as the problem I had with my first Grendel. After a lot of experimentation, I found out that the ejector pin was too long. As the round was being put in the chamber, the over-long ejector pin kept the base of the cartridge from sliding properly into the bolt face. You can see from your picture that the base of the cartridge is not inside the bolt face. The result is that the round was partly wedged into the chamber at an angle. When you pull the charging handle back a bit and release it chambers - right?

Take out the ejector pin, chuck it into a drill and abrade it against sandpaper (I used a belt sander) to take of a few hundred's of an inch. Chamfer the sharp corners with sandpaper. Since I made this modification, I have had zero issues with feeding.

--Rootshot

[warped]

Make sure that when you look at the magazine that both left and right hand rounds when at the top have a nose high angle to them.

[fanofflyn]

I have this problem too, and that makes sense. I'll give that a go. Also, look at the inside of the upper receiver at the place where the bolt carrier stops when you have the fail to feed. The front of the bolt carrier will make a gouge and a ridge where it is driven into the aluminum of the upper receiver. You will need to smooth this out and polish it. I did that alone, and it helped, but then the problem recurred and the upper receiver damage started again. The long ejector makes sense and that is where I will go next. It also explains why my first sign of higher pressure is an ejector mark before any primer flattening when making my loads. Thanks Rootshot.

--fanofflyn

[fanofflyn]

Hey, I'm excited. I pulled the bolt, and the ejector was very slightly long, especially compared to my other
Grendel bolt extractor. I took out the ejector, and shortened it, and very slightly chamfered the edges just to make sure, and mirror polished the end, and reassembled. Voila! Works perfectly every time! Thanks again. BTW, this was a new build with a Satern Cut Rifled barrel and matching bolt, so I'll send a note to the guys at Satern, unless they are on this forum.

--fanofflyn

[Rootshot]

Hey, I'm excited. I pulled the bolt, and the ejector was very slightly long, especially compared to my other
Grendel bolt extractor. I took out the ejector, and shortened it, and very slightly chamfered the edges just to make sure, and mirror polished the end, and reassembled. Voila! Works perfectly every time! Thanks again. BTW, this was a new build with a Saturn Cut Rifled barrel and matching bolt, so I'll send a note to the guys at Saturn, unless they are on this forum.

--fanofflyn

Awesome. Glad to hear that worked for you. I went through months of pain and suffering trying to figure this one out. I event sent it back to the manufacturer who returned it unfixed. After I fixed this, I contacted the manufacturer. They claim they haven't seen this on a Grendel but have periodically seem it on a 5.56.

--Rootshot

[rushmc]

How long ago did you buy the barrel? I got the same thing about 2 months ago. I have yet to fire it

I will check it against another I can look at too

Marc

[fanofflyn]

I just bought it about a month ago. I wrote Satern, and they said that unfortunately that was a problem with all the bolts, and that Midway should have contacted me (they did not), but that they would send me a new bolt if I wanted. Since I presume my current bolt is properly headspaced and now functions flawlessly, I prefer to keep the one I had. The person that wrote me back was Kim Hageman from the email address kimsatern@gmail.com if that saves you any time. I'm glad Rootshot did all the work for us.

--fanofflyn

[rushmc]

I was out roto-tiling my mother in laws garden last night (lives on a farm). So took the Grendel out to test the build. Thankfully it cycled and chambered just fine. Now if I can just get the time to site the thing in.

[warped]

Use your workmate work bench and clamp your rifle in, set up a target that you can see through the scope at 100yds, fire and adjust the crosshairs to the bullet hole.

Then fire a group at dead center on the target.

[warped]

If not, I'll shoot that sucker for you!

yesterday I did something very bad, I need new steel plates now...

[Airhog]

If not, I'll shoot that sucker for you!

yesterday I did something very bad, I need new steel plates now...

I'm going to bite Warped, no one else will. What did you do, shoot your poppers with AP rounds?

[robsf49ers]

Hey, I'm excited. I pulled the bolt, and the ejector was very slightly long, especially compared to my other
Grendel bolt extractor. I took out the ejector, and shortened it, and very slightly chamfered the edges just to make sure, and mirror polished the end, and reassembled. Voila! Works perfectly every time! Thanks again. BTW, this was a new build with a Satern Cut Rifled barrel and matching bolt, so I'll send a note to the guys at Satern, unless they are on this forum.

--fanofflyn

fanoflyn I have the same satern and bolt set up. The bolt they shipped did not come with a spring or extractor.I ordered this set up from Midway. I took a picture and emailed to midway they gave me a $5.00 credit.I removed the extractor set up from a 223 bolt and installed on the grendel bolt, at first the spring and pin did not want to slip in I had to use a pin driver to push it in it seemed very tight. No I did not use a hammer. Any way it does the same as your extractor does. I should send the bolt to Satern for an inspection.On another thread the owner of Satern posted he would take look at this problem, He mentioned some thing about he gets these bolts from out side vendors.