Gunsmithing Win/FN and Mcree TMAG--some pics added

[mark5pt56]

McRee's Precision G5-TMAG Fixed Rifle Stock

Thinking on this and had a question please.

It states that the Win/FN MAY NEED Some metal removed from the receiver(mag well area) for it to function with the AI patterned magazines. I understand this is common for the Win/FN's and stock that utilize the AI system. The big question is, once the receiver is modified, can you ever place the barreled action back into the original standard stock and it ACTUALLY work properly? I have seen some pics before from mods and they ranged from a professional job to someone using a drill and hacking it.
And no, I don't want a blemington.

I appreciate it

Mark

 

[mark5pt56]

Just bumping up to see if anyone had insight on the topic.

Mark

 

[StrayDog]

YES to all your questions, IIRC.
I had an FN/Mcree that fed well from AICS mags. Sold it back in the original mcmillan/FN DBM with no feed issues.
A proper FN/AICS Mod done right the first time should avoid the feed path, IIRC, but some folks' mods were removing too much metal IMHO.

 

[HodgdonExtreme]

I don't see how an FN could be fed by AICS magazines without a little machining in the front of the "magwell" of the receiver.

The magwell has a taper, getting thinner towards the front. It is wide enough in the rear, but needs some opening up towards the front. When I machined mine, I only removed material from the halfway point to the forward edge. The cut was deepest up front, but still only removed ~.063"/side of material.

I used a ballnose endmill to get a nice blend radius, and melonited the action after machining. You'd have to be VERY accustomed to looking at the FN actions to see it was modified at all.

Anyway, I've never tried feeding this action with anything other than the AICS-pattern magazines since the modification, but I don't think it would have any issue functioning as a toploader (A3G style), with the old DBM system, or the newer TBM. The modification is pretty non-invasive.

 

[mark5pt56]

Excellent! and thank you. I have a PBR XP I may have this done to but want the option of turning it back into the hinged plate. MDT intends to make the LSS and claim there's no mods but couldn't say how via email. I would only want the bare minimum removed-wonder who would do this properly?

 

[mark5pt56]

Ok, I measured three points on the AI magazine and corresponding points at the magazine well. (magazine-magazine well=minimum to be removed.
Front .860-.815=.045
Middle .875-.835=.040
Rear .890-.855=.035

I took pics and placed tape by the spots as I understand need to be removed. For clarification, the area in front of the magazine is left alone? I placed the magazine partially in to see how much was actually needed, not much at all if only the taped area is the spot in question.

Please correct me if I'm lost.
Mark

 

[HodgdonExtreme]

You've got it.

I didn't need to widen the magwell at all in the rear, myself. There again, I would looking for a really nice snug fit, so you might want to open it slightly back there.

I believe there is also a ridge that needed to be removed on the forward face of the magwell.

Here's mine. You can see how deep into the magwell my cut went, by the front corner radius's left by my ballnose endmill.

 

[mark5pt56]

Ok, so it doesn't need to go all of the way to the flat portion of the receiver(on the inside) Is it required to do that radius or as you mentioned that's from the mill bit? In my one pic, the front of the mag is a tad from the front of the well, if that's where it will actually seat once in the chassis. I measured the above with an actual AI mag, measured two Accurate Mags from the Ruger GSR and they are slightly smaller.(.010-.020, in all three spots)

 

[HodgdonExtreme]

Ok, so it doesn't need to go all of the way to the flat portion of the receiver(on the inside) Is it required to do that radius or as you mentioned that's from the mill bit? In my one pic, the front of the mag is a tad from the front of the well, if that's where it will actually seat once in the chassis. I measured the above with an actual AI mag, measured two Accurate Mags from the Ruger GSR and they are slightly smaller.(.010-.020, in all three spots)

You shouldn't need to lengthen the magwell by removing material from the front face of the magwell, but if memory serves, there was ridge or something in there, so I did make a *minimal* cleanup cut to that surface. Any material removal here is weakening the action's lower locking lug strength, so *minimal* cleanup is crucial.

I can't remember what diameter endmill I used - think it was .25", which is the MAX size appropriate endmill to use, because the front corners of my magazine nearly bind in the front corners of my magwell.

You don't need to use a ballnose endmill, but it makes a for a nice blend radius.

I advise you to fit your bottom metal into your stock and do some visualizing of how/where the magazine will be presented to the action via the bottom metal.

 

[mark5pt56]

Ok, thanks. I more than likely would have to send this off to someone to do as I only have a file set! I'm guessing you are not a FFL? This would only be on the Mcree mentioned, so mag placement is wherever that places it. When I'm ready, maybe they may know where/who. Why can't people just make the chassis for the TBM, dang it.