OK, I got tired of waiting for someone else to post how they did this, so I broke out the tools and went to town on my own MIAD Core.  Results are acceptable, however there were a couple of rough spots along the way.

All photos were taken in a hurry (don't ask) so no criticism of the quality.  I'm not proud, but they will do to illustrate the job at hand.  Also, my nails are dirty.  Live with it, I was working.  Sigh, you might ask why my nails are in the pictures at all?  They are there to cover up the 2 big honkin holes I drilled by mistake.  No Laughing!

You, there in the back, I said NO LAUGHING!

Anyway, here we go:  How to Mod your MIAD/MOE Bolt/Pin Core to accommodate not only the nominal Bolt and Firing Pin, but also a Cam Pin and 2 Firing Pin Retainers.

1.  UNLOAD THE WEAPON.  Put the ammo in another room.  Lock up the cat/dog while you are at it.

2.  Remove the Core from the grip.

3.  Remove the grip from the weapon.  This step is needed because you have to grind a tiny bit off of the back of the Front Strap in order to allow the Cam Pin some clearance.  Don't lose the Selector Detent and Spring.

You lost them, didn't you?  Go get some more.  I'll wait.

Done?

4.  Remove the Bolt and Firing Pin if they are already in the Core.  Also, remove the Front Strap from the grip.

5.  Obtain the following drill bits:  Number 37 and size O (as in Oscar).  For simplicity's sake, here are the decimal measurements for those sizes:  37=0.1040" and O=0.316" If you can't find those machinist sizes, here are some equivalents: The closest common matches are this: Use a 3/32" drill bit in place of the #37, the 3/32" bit will be a bit smaller than the #37 so you might need to 'adjust/wallow out' the holes to get them to fit the firing pin retainers without being too loose. Just go slowly. For the Size O, you can substitute a 5/16" drill bit. Again, the 5/16" is very slightly smaller than the size O, but they are so close it might not make much difference. Again, go slow and adjust to fit.

6.  Insert the Bolt into the Core.  You will notice that if you rotate and lift the Bolt, the top edge of the Cam Pin hole is just below the open side slits in the Core.  Using this as a guide, you can mark where to drill using the size O drill bit IN THE FRONT of the CORE.  This will be located just above the extension of the retention tab that runs about 1/3 of the way up the Front of the Core.  You can drill this hole a little too high, maybe up to 1/16" too high, but you cannot drill it too low.  If you do, you will just have to enlarge it up higher.  The Bolt bottoms out its Tail at the bottom of the Core and can't go any lower than where it naturally rests.  I erred about 1/32" too high and that was fine.



7.  Drill through only the Front side of the Core using the O (or 5/16") drill bit then deburr the hole.  You should now be able to insert the Cam Pin into the Bolt through this hole.



You may need to wiggle the bolt around to get the Cam Pin Hole lined up with the hole you just drilled.  NOTE:  The Cam Pin and its hole are Tapered, so it only goes into the Bolt from one side.

8.  Now, we can work on the holes for the FP Retainers.  Remove the Bolt, we don't want to damage its tail with the drill.

9.  Switch to the #37 (or 3/32") Drill Bit at this time.  We want to drill at a tangent across the Core in 2 places near the bottom.  Essentially, one FP Retainer will pass through the Core on each side of the Bolt Tail.  We need to be careful in drilling these holes because the drill bit will tend to wander and slip since we are not drilling at a right angle to the surface.

10.  You might want to start the drilling by using a small blade to make a dished starter hole for the drill bit.  Go Slow!  Remember, these holes should go through Both Sides of the Core.  When you are done, deburr and clean out the Core then insert the 2 FP Retainers like so:



And, from the other side:



11.  Now, reinsert the Bolt, making sure that the Tail passes all the way to the bottom of the Core without being blocked by the FP Retainers.  If there is any interference, you can try hogging out (that's a technical term used by Machinists) the FP Retainer holes to allow more clearance.  As long as the FP Retainer fits snugly in the hole on one side, the other side can have lots of slop.  Once this is all good, insert the Cam Pin locking the Bolt into the Core.

12.  Now, we need to work on the Front Strap of the MIAD (NOT the MOE grip, see below) to make some room for the Cam Pin we just put into the Core.  On the back side of the Front Strap you will notice that there are reinforcing ridges at various points.  We will remove the Reinforcing Ridge at the very Bottom of the Rear face of the Front Strap.  I used a Dremel with a cylindrical metal bit to grind this away in about 30 seconds.  We just want to take the Ridge down to the level of the surrounding plastic.

Like so:



And:



Note: With the MOE grip you do NOT have to make the modifications to the Front Strap. The MOE is molded with enough space to accommodate the head of the Cam Pin without any need for grinding, unlike the MIAD. Which is good considering you would need to stick the dremel up into the grip since the front strap is molded in on the MOE grip.

13.  So, now we can test the fit.  Insert the Core fully into the grip.  Then, insert the Front Strap into its mounting channel.  If you have done everything right, it all just fits.

14.  Remount the grip on to the weapon (which obviously necessitates removing the Core) then remount the Core with all your goodies attached.

Voila!  All Done!

Some Notes:  You can't put the Cam Pin in from either side of the Core, because the grip tapers as it goes up.  I know, the head of Cam Pin is in the shadow of the little 'wings' at the bottom of the grip, but it still won't work.  I've got the useless holes to prove it.  I was only able to get it to fit from the Front of the Core.

Also, none of these holes have to be exact.  If they are a little oversize the Cam Pin and FP Retainers will just rattle, and might fall out when you extract the Core.  Chances are if you are removing the Core, you wanted to get at them anyway.

You might want to try using a large O Ring to hold the Firing Pin in place because the plastic holder loses tension pretty quickly.

If you are a real Klutz and lose lots of FP Retainers, you can also use a small rubber band and attach at least 3 more of them to the Core, they can sit all around it lengthwise near the Firing Pin in the back.

Any Comments?

FluxPrism

Nice Mod!

Well done!!!

Thanks for taking the time to do the mod and write up.  I've been wanting to post something like that for two years.  Thanks!!

Very cool mods!


I'd try to find a way to include some pivot pin detent springs... since I tend to lose them.  :)


- BG

Originally Posted By BUCC_Guy: Very cool mods! I'd try to find a way to include some pivot pin detent springs... since I tend to lose them.  :) - BG

Actually, you can just add those on to the outside of the Core, the way I suggested adding extra FP Retainers.  (Those are what I break/lose...)

Just take a small rubber band and run it around the core above the retention latch, below the (newly installed) Cam Pin, inside the Firing Pin (we don't want to wrap the band all the way around the Firing Pin) and put the springs under the rubber band.  They will end up parallel to the Firing Pin and alongside the Firing Pin near the back of the Core.

Should work like a champ, just make sure you get the right size of rubber band.

FluxPrism

Uber.

Nicely done writeup.

Nicely done.  Always wondered why Magpul didn't make it so it would hold the cam pin from the very beginning.

That is slick!

Just got done doing it.

Originally Posted By Bumblebee_Bob: That is slick! Just got done doing it.

Did you find any problems with the instructions?  You're the first person to report back that they did it based even slightly on my writeup, so if you have any feedback, I'd appreciate it.

I'll tweak the writeup as I get feedback from folks and try to fix any errors that are pointed out.

Thanks!

FluxPrism

I had no problems at all. Very good write up. Thanks.

It would have been easier with a drill press, but things went well enough doing it with a hand held drill.

Cool! Good work!

Nice. I will have to try that.

tag

Bump for a thread that should have a thumb tac beside it!

Wes

Any chance Magpul wants to do this mod at the factory from now on?

Originally Posted By Wangstang: Bump for a thread that should have a thumb tac beside it! Wes

Wes

This thread needs a thumb tack!

Wes

Originally Posted By bolster: Any chance Magpul wants to do this mod at the factory from now on?

ETA: didn't notice the age.....

Thanks for the tack!

Wes

I guess this'll never be a factory mod?  I mean, MagPul "customer suggestion" improves everything else.  It would be cool for this one to get incorporated, too.

Originally Posted By Banzai: I guess this'll never be a factory mod?  I mean, MagPul "customer suggestion" improves everything else.  It would be cool for this one to get incorporated, too.

I don't think it has anything to do with them not 'wanting' to do it, but it would be very difficult to do it in a cost effective manner.

It might not be clear if you aren't familiar with molding, but if you look carefully you will see that there really aren't any 'holes' in the cores today.  By 'holes' I mean actual holes in a flat surface that go all the way through.  All the empty spaces are connected together and there are no standalone 'holes', due to the way that injection molding works.

Adding holes is very difficult and requires extra mold pieces.  That work doesn't come cheap, and would also slow down the production rate, which I bet is already just barely meeting demand.

So, it's not that they don't want to, it just isn't as easy as it seems.  And don't even ask how much extra effort would go into them chucking the things up and actually 'drilling' the holes after the piece is molded!  Talk about adding to the cost with all that handling and extra tooling, etc.

FluxPrism

sweet

Wow, excellent!!

Nice work!
www.magpul.com/catalog/index.php?main_page=product_info&cPath=78_104&products_id=216  

How'd I miss this?

Thats freakin' COOL.

+1 very good. now where is that box of bits....





 

Johnny Come Lately here, but, this is probably the single most useful thing I have seen on this board.

Well Done!

PS:

MagPul should make the bolt/pin core standard for MIAD kits.

I need to do this.

Very slick!

eta –– If my MOE grip & core ever come in, maybe I'll give this a shot.

Very impressive...the write up is easy to follow...will have my butler give it a go....JUST KIDDING, no butler, but maybe my grandmother, after she finishes moving my barbels to the attic!

I read this and laughed so hard I sharted!   Magpul......good idea here, make it and I will buy it.

BIG +1 on that. I'll never use the 3-round core.





 

Absolutely magnificent, thanks!

FWIW it worked on my new MOE without modification to the grip itself, and regular 5/16 and 3/32 drills were perfect (no rattle) with careful deburring using a razor knife.

Excellent DIY instructions. Thanks for taking the time to put this up. I used standard drill bits as close to the sizes in the post and it came out great. The little Dremel sanding drum is also a perfect fit to mod the front strap.

Well done!

I successfully modified mine last night using regular drill bits as close to the size indicated as possible, and my dremmel, and it came out fine, a little sloppy around the cam pin hole, but functional, thanks for the write up.

Grip core came in the mail yesterday, gotta give this a try.

I just got mine today, and already and modified it.  Thanks, FluxPrism!

I'm SOOO going to be doing this when i get my spare bolt and core!!!

Hello I don't know a lot about drill bits,  I went to Home Depot for the #37 Drill Bit and the O size but they had no idea what I was talking about.  Can anyone let me know where to get those or what standard bit sizes would work?

Yeah, the original drill sizes I specified are Machinist's sizes, and not commonly found at the big box stores.  Although occasionally they will have some of those '200 drill bit' sets with all the machinist sizes.

The closest common matches are this:  Use a 3/32" drill bit in place of the #37, the 3/32" bit will be a bit smaller than the #37 so you might need to 'adjust/wallow out' the holes to get them to fit the firing pin retainers without being too loose.  Just go slowly.

For the Size O, you can substitute a 5/16" drill bit.  Again, the 5/16" is very slightly smaller than the size O, but they are so close it might not make much difference.  Again, go slow and adjust to fit.

Hope that helps!

FluxPrism

Thanks.

My grip core for my MOE came in last night and I modified it with standard drill bits, turned out great!  Excellent idea and much better than the original design.  Might use a big o-ring or rubber band to secure the FP a little better, how well are yours staying in place after putting several 1k rounds through?

Eventually you'll need to use some sort of retainer to hold the firing pin in its holder. The tension of the holder goes pretty quickly in my experience. Most folks I've seen use a heavy duty O Ring or somesuch to hold the Firing Pin in its rest. They also sometimes use a separate rubber band to hold additional firing pin retainers vertically along the rear of the grip core. I guess some people lose those often!

Also, here's a good time to make a note for folks: With the MOE grip you do NOT have to make the modifications to the Front Strap. The MOE is molded with enough space to accommodate the head of the Cam Pin without any need for grinding, unlike the MIAD.

Which is good considering you would need to stick the dremel up into the grip since the front strap is molded in on the MOE grip.


FluxPrism

thanks


wish I was paying attention and started the hole for the cam pin on the correct side. . . .  dough

They could make dots or outlines in the mold and add something on their web site saying what they are for.

Funny, I just ordered a core this week and got it last night.  I had a new bolt/carrier in my spares and pulled it apart and I was thinking to myself that I wish there was a way to include these.  So glad this was posted and the search on ARFCOM works so great!  Have to do mine tonight or this weekend!

Awesome thanks

Can we have these pics reposted by chance?