Thoughts on drilling RR for Colt mag block?

[timspawn]

I am toying with the idea of drilling a registered receiver to accept a pinned in Colt 9mm mag block. I know everybody has a fit when it comes to drilling on a $10K lower but it can easily be returned to .223, only leaving four small holes which could be welded up if I ever got rid of it. Thoughts?

 

[drw]

For a shooter that is valued added modification! If it is ever available for sale, that is an added selling point.

 

[tony k]

In today's market, those four holes would cost you about $400 each in resale value.

Down the road, it could be $1k-$2k per hole.

As far as welding them up again ... would you tell the buyer that your RR has been welded on?

I wouldn't buy a welded RR at market price, and I would consider not telling the buyer about it to be less than honest.

Since there are drop-in blocks that work 100% as good as pinned-in blocks... why damage a collectible investment?

 

[tommygun2000]

Agree, modifying a collectable gun is not the best route in this case.

 

[azdskin]

I would not do it.

There are too many quality drop in 9mm mag wells for me to make a permanent modification to my M16.

 

[Tusk]

Not sure I'd do it, but if you decide to you might want to look at this. Installs with a single screw, very clean and minimal damage to the receiver.

http://users.zoominternet.net/~picplace/m16-ar15.htm

 

[timspawn]

OK I wont drill the holes! What is the best type of drop in block? I will be using Colt mags.

 

[amphibian]

Yes, I wouldn't drill the holes either. Now that you've decided to get block you have bunch of choices. There are many so I am going to save typing and not mention the "non-colt" mag options.
You need the bolt hold open capability.
All mag blocks that activate the STANDARD 223 bolt hold open are bottom loading. If they are BOTTOM loading they can fall out if not tight in the mag well.
These blocks are: (in my order of preference)

Hahn block - my favorite, the only one that has a slight flared mag well for fast mag changes. Also has the "feed grooves" cut in the feed ramp. Current model uses a set screw that pushes on roller to secure in lower. Older variant also had a spring loaded detent that went over the edge of the mag well on the inside.

Colt/RRA block - I've heard no longer made. Uses a set screw that pushes two pins from the inside out.

Crossfire/Tacblock - no longer made. Uses a spring loaded ball plunger that required a special tool to adjust.

Now you can also use a top loading block that has no way to fall out and use a 9mm bolt hold open catch also.
I've read that you don't need to modify the Hahn TOP loader for this option. But you do need to modify the ASA top loader. Garrison is also making one but I'm not sure if it requires mods.
Note that if you go this route then regular 223 mags won't work w/ the 9mm bolt hold open catch.
So it is a trade off.

 

[M60joe]

I wouldn't drill a RR either. But if you do want to pin a one piece mag block, you can hide one screw near the front lugs.

 

[timspawn]

What I have is a post sample Colt parts kit coming. It has two pins that hold it in. Somebody told me they bought a Colt mag block and it had the set screw that would lock it in. I dont know what type of block is coming with my kit. Will the Hahn bottom loading block work with Colt mags?

 

[az_gun_nut]

Why not just spend $120 and get a drop in mag block? Then you can switch back and forth from 9mm to 223 on the same lower?

ASA makes one and I'm sure there are others out there.

Brownell's sells them:

100-000-456 9mm Block
Retail $149.90
Dealer $119.96

 

[tony k]

What I have is a post sample Colt parts kit coming. It has two pins that hold it in. Somebody told me they bought a Colt mag block and it had the set screw that would lock it in. I dont know what type of block is coming with my kit. Will the Hahn bottom loading block work with Colt mags?

FWIW, I took the same approach (post-sample 635 parts kit). Most of the factory SMGs, including mine, used two mag blocks, a front section and a rear section. Initially, I sent the blocks off the C&S and had them both modified with set screws. The vibration from full-auto fire allowed the set screws to scratch up the inside of my mag well, so I switched to a one-piece Crossfire block. It has never left a single scratch, and has never come out during a mag change, so I'm content.

Most (but not all) of the bottom-loading blocks work with Colt mags, and most (but not all) will operate the bolt hold-open function after the last round in the mag is fired.

 

[timspawn]

My parts kit just came. The mag block is one piece with an allen screw in the bottom that, I guess pushes out two springs on the sides of the block. I will give this a try and see if it holds good.

 

[David Hineline]

Since you were willing to

since you were willing to drill your receiver then you obviously don't intend to swap calibers a lot.


Put some plastic shim stock on the mag blocks and pound them in tight with a hammer. That will hold better than the set screws which are going to mark the finish inside your magazine well.

 

[timspawn]

I just ordered two Hahn mag blocks. One top loader and one bottom loader. I'll see which one I like the best.