Take a look at this for me... (calling experts)

[PigOPs]

This round cycled into the chamber and I ejected it into my hand after hunting. Are these dings and markings normal? If not, I'm thinking one of two things:

1) My barrel has M4 cuts but my receiver does not.

2) My gas block is open too much. I am running an 18" midlength.

Thanks1

[Drifter]

If #1 is the case, it should be obvious, and it's not a difficult fix. If you're not comfortable doing it yourself, my guess is that Adco would do it.

As for #2, if your block is adjustable, it wouldn't hurt to experiment with less gas, which might reduce the violent feeding.

The dents might occur during feeding, or possibly when the bolt rides over the top cartridge in the mag. If you have a different mag that holds the top cartridge a little lower, it might worth trying to see what happens.

Some dings and dents are gonna happen, but it's a good idea to reduce 'em as much as possible.

[PigOPs]

I've thought about using my dremel to grind out some m4 feed ramps. Is that how you would suggest doing it? The block is adjustable... I'll check that out too.

[Drifter]

I've thought about using my dremel to grind out some m4 feed ramps. Is that how you would suggest doing it?

That's how I blend mine.

[Variable]

I'm no expert (LOL!) but I've been around a while.

Looks like fairly normal dings to me.

1.) Your rifle will likely run whether your upper has M4 ramps or not, but it would be helpful to add ramps that blend into the barrel extension.

2.) Sure, if you have an adjustable block on your rig--- turn her down and then slowly open it up to where it'll just lock the bolt back on an empty mag when firing. Now open it up just a bit more to insure reliability. That'll be gentler on your rifle and brass both. You'll likely want to do this with the wimpiest load you normally use, that way it'll cycle the widest selection reliably.

[skyfish]

I would guess that is from the bolt going back, the mag holds the cartridge a little high. The lugs on the bolt head are making that.

[rasp65]

It is not abnormal for a semi auto to make marks on the brass during cycling. To prove a point lock the bolt back, stick your finger in the ejection port and drop the bolt. As you can see the case is subjected to violent movement, so anything it hits will leave a mark like on your finger. You may be able to find the source by putting a line on the case head and orient the cartridge in the mag so it faces up. Cycle it through and since you know how it was sitting you should be able to tell what it struck. Then you can polish the place with some crocus cloth until there is no more marks on the case. Check out this page for what areas to clean-up http://www.snipershide.com/forum/ubbthre...er=1944031 If the case was only cycled by hand the gas block should not have any effect.

[PigOPs]

that makes sense... i'll check it out.

[sneaky one]

rasp- good find on the fix on that issue.

[LRRPF52]

This is how I like to do barrel extensions-basically a meltdown so the feed ramps baby the brass. The feedramp area is the weal link pressure-wise, so don't get carried away. It has a surface hardening with the heat-treating. Notice how much different this looks than the one shown on the pics on The Hide.