Worried about new Shilen barrel

[poli]

I got my Shilen barrel from Midway at the beginning of this week and eagerly I went ahead and finished my new AR. I loaded a few rounds in the mag and cycle them only to see them full of scratches after extracting them:

Shilen_SST.jpg

If I drop the bullet into the chamber manually (not from the mag), let the bolt carrier close and extract it, there is no scratch on the bullet.

The barrel is brand new. I measured the chamber with the Hornady bullet comparator with the proper 6.5 Grendel insert and I got 1.677-1.678. The factory Hornady 123gr SSTs that I used measure 1.674, so there is no issue with short chamber. It appears to me that the feeding ramps are the culprit. Before installing the barrel I polished the ramps a little with IOSSO (like I saw in a post on this forum).

I contacted Shilen few times and they keep taking my name and number saying that someone will contact me but so far no one did. I'm getting ready to go out and shoot this weekend, but before I want to know if it's safe and if anyone here has any suggestion on how to fix this.

This is my first and only AR (well, I have a Sig 556 but that's a different animal).

[Adam Lilja]

Polish it with a Flex-Hone. You probably have multiple burrs right in the throat where the neck meets the rifling. Be careful not to force the hone into the throat to deep though or you can risk damaging things from the hard tip on the hone. The rings near the neck can only come from the bore. The strange patterns near the tip look eerily similar to lands as they seem evenly spaced and almost have a consistent twist to them. All that other crap could be from feed ramps, depending how many times you tried to feed each round. I think I would also run a bronze brush thoroughly through the entire barrel in case its not from the chamber reamer.

[Tedward]

Adam, Good info on that brush! link: http://www.brushresearch.com/brushes.php?c2=183

I will say I bought one of the Shilen Barrels to just check them out and the measurements came out with CBtO @1.680, right in line with yours. The OAL was 2.251. I didn't notice any marks but when I fired it had cycling issues. I called them and spoke to some guy about the issue and he said he knows nothing about gas ports or AR's. They just make barrels and said to call someone who might know. I called a guy and got an answer that helps and resolved my questions so the CS Sucks.

I will say I put 3 Lilja barrels together today and they all test fired on round one, not feed issue and I didn't notice the scuffs, my bullets went forward down range.

[poli]

Polish it with a Flex-Hone. You probably have a burr right in the throat where the neck meets the rifling. Be careful not to force the hone into the throat though or you can risk damaging things from the hard tip on the hone. The rings around the neck can only come from the bore. All that other crap could be from feed ramps, depending how many times you tried to feed each round.

Thanks Adam. I polished it with IOSSO on a piece of cotton wrapped around an old .30 brush, but I might've not done it enough. These rounds have been tried twice. You should see them now after about 10 tries... Is it normal to scratch the bullets like this when loading them? I also polished the ramps but again I might've done it to little. Is it advisable to do it more, or should I just go ahead and shoot it?

[Adam Lilja]

My personal barrel I can drop a round in and push to the 'stick' point and then extract w/o even the iddiest of the biddiest of a nick or scratch. I would buy the hone and ditch the .30 brush to avoid damaging anything. They are cheap, and you use them more than you would think. Those are not normal scratches at all.

[StoneTower]

Those look like barrel extension scratches to me. I have an Armalite upper in 22-250 that did that when I got it. I was told to shoot it and that after a while it would go away. The ejector pushes the loaded round against the barrel extension when a loaded round is ejected. You can take a magic marker and color the bullet. Drop the cartridge in the chamber and push the bolt closed (upper removed from lower). Open the bolt slightly and then make sure the ejector does not push the bullet against the barrel extension. You will probably not see any scratches.

[45r]

If you can borrow or buy a ceramic stone that is rounded about the size of the extension gaps and pull it against the inside corners it will smooth them out.
I got a couple white and ruby that are round on one side and square on the other and they work great for a lot of uses.
Brass and bullets will eject with no marks or scratches.
If you use Iosso or JB's drape a round patch over a 243 nylon brush and spin it in the throat area using a pistol rod for a little while in a cordless drill.
A 30 cal metal brush is too big and scratchy to be spinning in the throat.
Don't go in too deep.
The metal end might hit the rifling if it somehow pokes through the patch.
The hone would do the same polishing to the throat faster.

[Crippleshot1]

Adam which size Flex Hone brush would be best for the 6.5 Grendel chamber? It does not list that chamber on there web site. I was thinking the 7.62 x 39 or maybe the .357 mag/.38 spl.

[VASCAR2]

I have a 20" Shilen Barrel I bought from Midway in 2012. Mine scratched up the bullets while feeding. I think the bigger bullets hit the barrel extension during the feed cycle. Take your Shilen to the range and shoot it, I'd be surprised if you don't like it

[LRRPF52]

The marks often come from dragging against the barrel extension teeth, and are normal for rack-grade guns that use the cheapest extensions as possible.

Blown-up images magnify the features to a point that most people are not used to seeing, and it's easy to jump to conclusions.

I like to polish my barrel extension feed ramps and take edges off where the projectile, neck, and shoulder interact with the extension.

You will also get pretty bad scratches from extracting the cartridge, as mentioned by StoneTower, where the ejector is forcing the cartridge to bind against the inside of the barrel extension teeth.

Can we see pics of your barrel extension?

[poli]

The scratches threw me off since my only experience with AR platforms comes from my Sig 556, and that gun is smooth as silk. I was afraid that the bullets get scratched during the loading process and that might affect accuracy, but if it happens during extraction (and from what StoneTower and LR are saying it makes sense), then I'm not too concerned. Where I'm not clear though is why would the bullets get scratched when I'm loading them from magazine? If I drop the bullet into the chamber, then let the carrier group shut close and then extract, the bullet is not scratched.

I'll mark the bullets with color like StoneTower suggested and also take some pictures of my barrel extension and post them when I get home tonight.

I believe the tool Adam suggested works great - I just wish they had a magic one-size-fit-all for that price .

[LRRPF52]

The bullets spin at tens of thousands of rpm, so accuracy would have to be measured at 1000yds to see any effect, if any.

[poli]

When I started thinking about building an AR platform I was set for an AR-10, but after I was introduced to 6.5 Grendel and read all the good things about the cartridge I decided to build an AR-15. My goal was to get a good all around AR that can use for hunting and also shoot long range to 1000 yd. The scratches are not cosmetic, they are deep into the metal. I see your reasoning with regards to accuracy but my primary concern was accuracy at long range.

[LRRPF52]

My .260 Rem AR10 does the same thing to the 130gr Berger VLD's. It can put them into 5" at 1000yds. They look thrashed when I extract a live round.

My first time shooting it at 1000yds, I was in the bed of my truck, off the bipod. I shot 3 rounds into 9.25" with a wind speed shift I didn't even hold for. The mirage was boiling, so I just aimed at what I thought was the best center of a boiling black bullseye, and fired my string. I wondered if I would find any holes in the target at all as I drove out there.

I came up on it and was pleasantly surprised to find the sub-MOA group, as well as a very flat trajectory through the double-layered cardboard box (baby mattress box). I wanted to get an indicator of what my danger space was like, having shot a lot of .308 at 1000yds and farther. There was hardly any elevation difference between the entrance and exits...truly scary.

I'll have to repeat the same tests with the Grendel this spring. Might even be able to do it within the next few weeks if I can get my reloading operation set up on the new bench.

If you want to reduce a lot of the projectile gouging, make your feed ramps look like this:



Steps I take when doing it:

* Pre-fit the barrel and extension in the upper receiver to see the mate-up of the extension to the feed ramps in the upper. They are rarely matching, and often bad enough that an M4 extension will lip over into an M4 upper. I use a black marker to indicate on the feed ramps what needs to be be blended in order to get a nice fit between the two. This is especially important when shooting any of the BTHP's, and even more so with the Sierra Game Kings.

* Next, I make foam plug and seal up the chamber so that no polishing compound can get into the chamber during the work.

* Then I take a flexible polishing tool head in the Dremel/Ryobi, and start polishing the ramps. I also take off the edges so that my brass necks and especially the shoulders don't bash into the sharp edges. If you look at the extensions we got with the Lilja barrels, the are the most beautiful, superb AR15 barrel extensions I have seen, and most of the work I normally do has been done when they were tumble-brushed. I'm gonna have to file a complaint with the union.

* Once I feel like I have made a little headway, I test-fit the barrel again into the upper, and look at the mate-up. I go back and forth until I am happy that the extension is blended and polished.

I do not change the angle of the feed ramps.

[LRRPF52]

Here's a video on youtube that shows one way of approaching it. I preface this as I mentioned above, by plugging the chamber with foam to prevent any unwanted and potentially chamber-damaging compound from getting in there. I also take the polishing head over the edges of the feed ramps to "melt down" the sharp surfaces, and those of us with the Lilja barrels can see that has been done by the tumble polish already.

http://youtu.be/jMe0_HgkYEQ