J Allen Chassis and magazine play

[Torchy]

Hi all,

I have 2 of the most current versions of J Allen Chassis and I think their flawed. Now not just my 2 but in general.

Anyone else get a magazine all adjusted for proper case head height in relation to the bolt for cycling and realize there is a lot of up/down slop with their mag?

Tried this with a magpul and an AICS mag and they both have a good amount of up/down play to the point where if you were to push up on the mag with the bolt back, the bolt will not close (hits back of feed lips of mag).

These were both tried with 2 different deviants (identical results with both actions) and with a Vector. Due to bigger vector bolt, it was even worse.

Is an AW mag the ticket or does everyone experience this?

I shoot in matches and if I’m on a stage we’re the mag is pushed up, I can’t cycle the bolt so theres relevance to this.

Let me know what yall think!

 

[Yerman]

 

[Torchy]

Yep thanks for that. Watched it 10 times and I do love j Allen and Lisa but this does not address the OP. Neither of those adjustments address up/down play of the mag to chassis once you set your round height.

 

[Yerman]

If I'm reading correctly, you have two issues. 1.) you can't close the bolt on an empty mag and 2.) you have vertical slop in your mag? If I'm not reading this correctly, please let me know.

I am running a Defiance Deviant (Area419 version), Lapua long action with an AI mag.

For 1.) I had to file down the back of my follower to gain clearance. Pic below.

For 2.) I don't have any slop in my mag so can't help there. However, I would play around with the mag catch adjustment in the video and possibly you need to look into making feed-lip adjustments. MPA makes a tool for this. https://masterpiecearms.com/shop/mpa-mag-feed-lip-adjustment-tool/

Hope that helps.

 

[_Raining]

For AICS:

In my experience, the front of the mag cut in the action will prevent the front of the magazine from over inserting but nothing stops the rear of the mag from over-inserting with upward pressure.

The exceptions for this is the MPA which as the ability to add a block to prevent the rear from over-inserting and the Xylo which has a hump on the mag latch to prevent over insertion.

I cant comprehend how other people can even say they can close the bolt with upward pressure on the back of the magazine when using non MPA/Xylo chassis. But I guess I am just insane because I constantly see people say this isn't an issue for them.

 

[Dthomas3523]

If you’re running aics mags in AW cut actions, then yes, on some you can over insert the mag and bind the bolt.

Vectors are well known for this.

 

[Dthomas3523]

Get aw mags and adjust them to seat with the lips up as high as possible with the bolt closed. Then adjust a little play.

It’ll likely feed when setup that way or with a little adjustment.

 

[Torchy]

If I'm reading correctly, you have two issues. 1.) you can't close the bolt on an empty mag and 2.) you have vertical slop in your mag? If I'm not reading this correctly, please let me know.

I am running a Defiance Deviant (Area419 version), Lapua long action with an AI mag.

For 1.) I had to file down the back of my follower to gain clearance. Pic below.

For 2.) I don't have any slop in my mag so can't help there. However, I would play around with the mag catch adjustment in the video and possibly you need to look into making feed-lip adjustments. MPA makes a tool for this. https://masterpiecearms.com/shop/mpa-mag-feed-lip-adjustment-tool/

Hope that helps.

View attachment 7347366

My bad, wasn't specific enough. I can close the bolt and when I insert the mag and slightly pull down on it, that is where she is perfect. She cycles flawlessly no matter how hard I run it. To answer part 2 of your question, I don't believe there is vertical slop in the mags. I have 4 different magpuls and 2 AICS and they all have the same amount of up/down play/slop in these 2 chassis.

So unlike you, if I adjust the mag up more, yes that direction of adjustment will take a lot of the play out but that in-turn pushes the back of the feed lips of the mag into the path of the bolt.

 

[Torchy]

For AICS:

In my experience, the front of the mag cut in the action will prevent the front of the magazine from over inserting but nothing stops the rear of the mag from over-inserting with upward pressure.

The exceptions for this is the MPA which as the ability to add a block to prevent the rear from over-inserting and the Xylo which has a hump on the mag latch to prevent over insertion.

I cant comprehend how other people can even say they can close the bolt with upward pressure on the back of the magazine when using non MPA/Xylo chassis. But I guess I am just insane because I constantly see people say this isn't an issue for them.

OK you basically nailed it. Yes the front of the mag, when inserted, doesn't have much up/down play, but the back of the mag does.

Going to try to illustrate this in pics. Keep in mind that the mag is already adjusted to as high as I can get it with protruding into the bolt path. That said, there is rear slop at this adjustment.

This pic, the mag is pulled down and where it functions flawlessly. Notice the feed lips of mag are parallel to the receiver races (which is how I think it should be) also notice the back of the feed lips are just a hair under the bolt path, meaning mag is adjusted as high as it can be without protruding into the bolt path. Also remember, the higher I adjust the mag, the more it solves my problem aka takes out the slop.



Now in this pic, I am simply just pushing up on the mag. There is about .1-.2 of an inch slop that is allowing the rear of the mag to move into the path of the bolt. Also you can see how the front of the mag doesn't move up much but the rear does. I'd have to cut a pretty huge amount of material off the feed lips to make it work. At that point, I am not sure they'd hold a round in.

 

[Torchy]

If you’re running aics mags in AW cut actions, then yes, on some you can over insert the mag and bind the bolt.

Vectors are well known for this.

Makes me feel a little better that I'm not alone here lol. I have no problem running AW mags in these rifles if that will help. And yeah the vector was worse.

 

[Torchy]

Get aw mags and adjust them to seat with the lips up as high as possible with the bolt closed. Then adjust a little play.

It’ll likely feed when setup that way or with a little adjustment.

Makes sense and that is basically how I am adjusting them anyway. As high as possible without protrusion into the bolt path.

 

[Tokay444]

Yeah, it’s an AICS pattern issue. Not a J Allen flaw.

 

[Torchy]

Yeah, it’s an AICS pattern issue. Not a J Allen flaw.

That sure would be cool if AW's fixed this. I'm going to buy a AW and try it out and report back. In the mean time I can probably borrow one from a friend.

 

[Perry41arms]

That sure would be cool if AW's fixed this. I'm going to buy a AW and try it out and report back. In the mean time I can probably borrow one from a friend.

Hey bud, just following up if you managed to fix the issue with an AW mag ?

 

[cgobeli]

I just stumbled upon this thread as I am having similar issues. As I am reading through this I was getting excited that maybe I was getting somewhere, but then it just went cold.

 

[Tokay444]

I just stumbled upon this thread as I am having similar issues. As I am reading through this I was getting excited that maybe I was getting somewhere, but then it just went cold.

Running AICS mags in an AW cut action?

 

[cgobeli]

Running AICS mags in an AW cut action?

I'm running aics (magpul & MDT) in a Tuebor action. Tuebor says the action is not cut for AW, but the aics mags travel high enough to bind the bolt when there is pressure on the mag.

 

[Tokay444]

That’s not a J Allen problem. It’s an AICS problem.
The mag catch is unidirectional. It only stops the mag from falling out. Neither the catch nor the magazine lip are setup to restrict how deep the mag can be inserted.

 

[cgobeli]

That’s not a J Allen problem. It’s an AICS problem.
The mag catch is unidirectional. It only stops the mag from falling out. Neither the catch nor the magazine lip are setup to restrict how deep the mag can be inserted.

I know it's an issue with my aics mags (magpul and mdt). Also I do not have a J Allen, I have a Grayboe.

When I was looking at the problem last night I noticed that the catch on the mag eventually stops the magazine from traveling upwards. Masterpiece Arms actually came up with a little insert to help limit the upward travel on their chassis that I am going to try to replicate.

Mag Block Insert - MasterPiece Arms, Inc.

Mag Block Insert This insert is designed to fit into the mag catch slot in Short Action MPA BA, BA Comp & Hybrid Chassis. This part was originally designed to work with Curtis Custom Vector Actions, for customers who wanted to run AICS magazines (on an AW Cut Action), to eliminate the gap before...

masterpiecearms.com