McRee / AICS magazine feed issue WITH PIC!!

[DTL]

I searched, but only found about 143 threads covering AICS feeding issues. I figured at least one more was in order! In all seriousness, I didn't see one that covered my "exact" issue. I've got 3, 10rd mags that all have the same failure in my McRee chassis'd Rem700. As the bolt moves the round forward, the bolt rides over the top of the round and everything crashes to a halt. (see pic). My one 5-round mag works bitchin', no failures at all. Is this a "feed lip" issue, or is something else going on here?

Thanks!!

 

[Bradaus]

I would open the feed lips ever so slightly to let the back of the round sit a bit higher.

 

[SWRichmond]

Perhaps the thread should be titled "McRee chassis feeding issue with AICS magazines"? I would think it entirely possible that the chassis is mis-positioning the mags.

 

[SporterII]

Look also at the possibility of adjusting the release. I had to lengthen one .040 to cure a similar feeding issue. Mag to bolt clearance was too great.

 

[Terry Cross]

or is something else going on here?

I think your image shows a clue worthy of checking out. Probably not a magazine issue. I would not suggest opening your feed lips as they are likely fine and opening could cause a problem worse than what you have.

We can see the Z-axis offset between the feed lips of your magazine and the feed rails of the receiver (that the AICS mags are supposed to bypass). That gap looks too large.....

If so, this positions your magazines too low in relation to the bolt raceways and you get bolt override as shown in your picture. The fact that your 5rd works is just luck with tolerances.

If this was separate bottom metal, I would say your pillars are too long or pinch points between action inlet and bottom metal inlet is excessive.
In the case of a chassis, your mag latch is too short or the mag latch pin hole was placed incorrectly throwing a good mag latch out of position.

Probably something else but wanted to throw my 2 cents out there.

Terry

 

[DTL]

Thanks for the feedback everyone. I'm planning on contacting McRee and seeing what they have to say. In the meantime, I took a micrometer to the mags that I have. The magazine catch to top of mag are all the same height. The top of the follower to bottom of the feed lips are all the same. There was one difference though. The feed lip width on the 10rd mags was all .374"-.375". The 5rd mag feed lip width was .409". I don't know if .034" is enough to cause the issue I'm having, but it's the only tangible difference I've been able to find so far.

 

[SWRichmond]

um.....perhaps I spoke too soon, the feed lips on my .308 5 rounders are .395" and .403" respectively, and my ten rounders are all between .405" and .410". My mags are all AI marked. The feed lips being too narrow would definitely hold the round too low. I still wouldn't bend them myself...are they new? Can you return them?

 

[cal50]

Get a piece of painters tape and insert the magazine (with the mag release lever depressed) until the magazine makes contact with the bolt body. Use a piece of painters tape to mark the magazine so you can remove it and re-insert it to the same point. Load a round and insert the magazine at this same point and try feeding some rounds.

It sounds like the magazine / rounds are sitting low.

 

[DTL]

The mags are new. They came from Midway, so I'm sure I could send them back.

I'll try the masking tape trick. When I was messing with this last night, I held the mags up, by hand, while I ran the bolt and there was no difference in operation. There's some vertical play, but it doesn't feel like much. I haven't mic'd it.

I left a voicemail with McRee, so I'll see what their input is when they call me back.

The only other potential issue I was considering is the Ceracote on the chassis. It came Ceracoted from McRee and they painted EVERYTHING, including the bedding block area. I can't imagine that stuff is very thick (a few thou maybe?) but even if it's .0001", it's still raising the action by something.

 

[DAVETOOLEY]

Is your action modified to accept the double stack mags?

 

[DTL]

The action is stock.

Some more interesting measurements: The magazine can move .053" up and down. That's with it inserted in the chassis, then measuring while I pull downwards, then push upwards.

Under the category of "better to be lucky than good" it appears I may have solved the issue. I did exactly what I should NOT have done, and went to the toolbox, grabbed a set of smooth-jawed channel-locks, a fine file and the micrometer. I opened the lips on one of the 10rd mags to .410" (similar to my 5rd mag that works) and voila; it runs. So, of course I abused the next 2 problem-mags and they seem to function correctly as well. I'll keep an eye on the situation, but for the time being, it appears that this WAS just a feed lip issue.

A sincere thanks to everyone who chipped in with advice. This is the first time I've ever messed with these magazines, so the guidance was definitely appreciated!