AI question

[photorestore]

Hey guys,

I just bought a short action AX about a month ago and every round I have fired through it seems to have ejector marks, even factory ammo. Have any of you guys seen this before? Here is a case from today that was a pretty "mild" load. 41 grains of H4350 with a 140 ELD. Like I said though every case fired from this rifle has it. What's weird to me is the drag mark next to the ejector mark. I've never seen that before I bought this rifle.

 

[Bradu]

Curious to see what you find out, a friend's ai 338 does the same thing with mild loads according to different books and quickload.

 

[photorestore]

Curious to see what you find out, a friend's ai 338 does the same thing with mild loads according to different books and quickload.[/QUOT
Bradu on a hunch tonight I pushed the ejector in with a plastic rod and it felt really gritty. I dropped a couple drops of oil on the ejector and then pushed it in and out to draw the oil into the ejector channel. What came out were black chunks that looked like the coating that's on the bolt. After that the ejector is much smoother. I don't know if this is the problem or not but it might be something for your friend to try with his .338.

 

[Supersubes]

Any idea what your velocity is at that charge weight?

 

[Timo Turl]

Are you using new brass or FL sized brass ?

I found similar when I used bumped brass shot in another rifle.

 

[photorestore]

Any idea what your velocity is at that charge weight?

I'm not sure off hand what the velocity of the 41 gr. charge was (I can check my data book) but I settled on 41.3 gr. which was 2775.

 

[photorestore]

Are you using new brass or FL sized brass ?

I found similar when I used bumped brass shot in another rifle.

This happened to be new brass but it happens on bumped brass also. When you saw it on your brass did it have the "drag" mark next to the ejector do you remember?

 

[OH58DViper]

One of mine did this with factory Ammo as well, it was due to a short headspace issue. Once I bumped the shoulder back for that specific chamber it stopped. Mine had a huge drag mark on it as well, looked like it was way over pressured but remedied the problem with .002 bump back. Mine would actually leave the drag mark with just chambering and then unloading. I had brass that looked like it was shot with high pressures with the primer untouched.

 

[photorestore]

One of mine did this with factory Ammo as well, it was due to a short headspace issue. Once I bumped the shoulder back for that specific chamber it stopped. Mine had a huge drag mark on it as well, looked like it was way over pressured but remedied the problem with .002 bump back. Mine would actually leave the drag mark with just chambering and then unloading. I had brass that looked like it was shot with high pressures with the primer untouched.

I thought of that too and chambered a couple rounds and then ejected them but the marks weren't there. My previous batch of brass I bumped .002 but it was still on there. I think I'm going to run some headspace gauges in the chamber tonight just to make sure everything is cool in that way.

 

[diverdon]

Is it an after market barrel or the one that came on the rifle?

 

[photorestore]

Is it an after market barrel or the one that came on the rifle?

It is an AI barrel that came with the rifle.

 

[Fig]

I agree with some of the above that you're a little shy on headspace. I've had identical marks for the same reason. Not enough to cause a light strike, or FTF, but enough that the brass has room to move and is impacting the bolt-face upon ignition. You're probably only 2 thou off where you need to be. A little longer and those will go away.

 

[photorestore]

I agree with some of the above that you're a little shy on headspace. I've had identical marks for the same reason. Not enough to cause a light strike, or FTF, but enough that the brass has room to move and is impacting the bolt-face upon ignition. You're probably only 2 thou off where you need to be. A little longer and those will go away.

That makes sense. I'll re-measure my once fired brass tonight and make sure that the length that I had from before is accurate.

 

[diverdon]

It is an AI barrel that came with the rifle.

If mine did that I would PM Tom Irwin and ask if he can help solve the issue.

 

[Badfinger]

Since it marks every case I wonder if the ejector is a little long? I would contact AI or Mile High Shooting.

 

[photorestore]

If mine did that I would PM Tom Irwin and ask if he can help solve the issue.

Great! Thanks for the name. I sent a message to AI through Facebook because I wasn't sure who to specifically get in touch with. Tom Irwin is on the hide?

 

[photorestore]

Since it marks every case I wonder if the ejector is a little long?

That could definitely be. I checked the ejector last night and it seemed a little gritty. I dropped oil in the ejector channel and pushed the ejector in and out to get it down in there and to bring whatever grit was in there out. There seemed to be some black flakes which looked like the coating on the bolt. It is smoother now. I wonder if it was just enough so that the ejector wasn't moving freely.

 

[Supersubes]

I’ve seen a few AI’s that have really sharp edges to the features in the bolt face. My AXMC does this slightly on the extractor cutout. Looking at your case, the vast majority of your swipe is at the extreme edge. The most unsupported portion of the case head(nothing but rim thickness). It even left a burr on the case head where the cutting stopped, at the end of the bolt travel.


Edit: Ejector marks are caused because the case head extrudes into the ejector hole, which later shears off on bolt opening. The area of the case head beyond the ejector (long tail of the cut) in your pic would have been supported at the time of firing, and would not be able to sit proud to later be sheared off. Your bolt face is causing this.

 

[photorestore]

I noticed that burr too. I was wondering if it could be sharp edges.

 

[Fig]

The half circle mark is where the ejector plunger was impacting the case head. That can be present even before a primer starts to flatten in an overpressure situation. Since it's happening with all ammunition, and overpressure is ruled out, I have to think that the chamber is simply cut a little (slightly, even a couple thou) too long.

 

[photorestore]

The half circle mark is where the ejector plunger was impacting the case head. That can be present even before a primer starts to flatten in an overpressure situation. Since it's happening with all ammunition, and overpressure is ruled out, I have to think that the chamber is simply cut a little (slightly, even a couple thou) too long.

That definitely makes sense to me.

 

[photorestore]

If mine did that I would PM Tom Irwin and ask if he can help solve the issue.

Ooooh now I know who Tom Irwin is. Sometimes I'm an idiot. Ok well I PM'ed him, we'll see what he says.

 

[photorestore]

So the official word from AI is that there was a burr around the ejector channel opening causing the marks on the brass. I believe they are replacing the bolt head. It was supposed to ship back to me the beginning of last week but never did. Then it was supposed to ship today but didn't. I'll let you all know what they did for sure when and if it ever comes back.