I've all but decided that my next Title II project will be an M-203. I have cans, SBS', SBR's, and AOW's, and have had some MG's in the past. The only thing I have not yet owned has been a DD. It's time I correct that error. This won't happen overnight, obviously. In fact, I'm probably not even going to buy the receiver (so I can do it on a Form 1) until December or January. But, I need to start budgeting for it soon. So, I have to decide how I'm going to build it.

Do I go 9" or 12" barrel? Do I go rail-mounted or standard? Do I just do it mounted on a rifle, or do I also pick up a pistol frame or a stocked-stand alone frame? If you were building one, what would you do?

Poll coming soon.

Much depends on what you plan on using it for. If it is simply a safe queen, I'd go 12" attached to a retro slick side AR platform, but that is my personal preference as I carried one just like that way back when.

I have two M203s and an M79. One 203 is mounted on a 40cal pistol carbine upper AR with a 9" barrel, I call it my 40/40. I keep it close at night and use it for home defense.  It is short, the 40cal upper holds 20 rounds of black talons, and the 203 vest has many options for possible needed munitions...

My 2nd 203 is mounted on a stand alone folder from Israel. Equipped with a 12" barrel for length and to check for possible projectile/barrel impacts with flechette loadings. I use that for T&E as I evaluate many 40mm experimental munitions. ( Hey, someone has to...) I have it mounted that way as it is easy to take to the range, carry around with no need for a host weapon and added weight.

Good luck, and happy building. GROG

I ordered a standard mount as that is what I think of when I think of a M203.

Barrels can be found on gunbroker.  12 inch barrels being cheaper than 9 inch barrels.  So if you wanted both, you could get the other one.

I ordered mine with a 12 inch barrel, purchased a 9 inch barrel on Gunbroker.

I also got a good deal on a LMT stand alone mount on gunbroker.  While a M203 on a rifle is cool, it may be handier to have it separate.

When I carried one, it was always a 12" version on either an M-16A2 or an M4. Mostly, my planned use is "because I can" and "it fills a hole in my NFA collection." I'm sure the most common round I'd fire would be TP, though I wouldn't mind having some of the other assorted rounds down the road.

Currently, I'm leaning towards a rail-mounted 9" version, which could be moved around among my various rifles, should I desire to do so. But, having never fired a rail-mounted M-203, I figured I'd see if the folks here had any inside experience which pushed them away from rail mounts. And, having no experience with the 9" version, I don't know if the shorter barrel would be a detriment to range or accuracy. (The most common host would be my 10.5" 5.56 AR, so a 9" barrel seems to be more of a natural fit to me.) If I do get one of the stand-alone mounts, it won't be right away. But, again, having never used one, I don't know if it'd worth the money, or which one would be more enjoyable and worth the time sleeping on the couch.

To me there's just something about a 203 mounted to an m16/ar15 platform.

As for rail or barrel mounted, that's up to you. I chose barrel because it seemed more secure and tucked in a lot nicer to an m16. The rail seemed bulkier and not as well flowing. Barrel length doesn't really matter accuracy wise from what I have heard. I went 12" just because I liked the way it looked and I can move it from a m16a1 upper to m4 and keep the same barrel. That said, barrels aren't hard to swap out either.

The only difference between the barrels is 3". I have both lengths just for clone appearances. Mine is a standard mount with KAC QD. The barrels are QD on either model launcher. There is nothing QD about the mounting of the M203-2003 (railed receiver) itself, although it is certainly mountable to more hosts. I'd like to get a FAB Defense / Mako standalone folder like Grog has. I normally just leave it on one of my M4's. Sometimes I go old-school M16A2 mode (by swapping brackets). Last I checked, it is less expensive to F4 the complete factory DD, and additionally more desirable later if you sell it, as it won't have your engraving on it.

If it were me (hope it is eventually), I'd go with a 9", standard mount, with a stocked stand-alone kit.  

~Augee

Rail mount ftw. Mine is in jail right now, but should be out in a month or two. I like being able to put it on different guns, and I've already set up an AK to mount it to when I feel like it, and the CETME will be next. It's home will be a monolithic AR SBR, but why not have the option to mount to other stuff? Some pretty wild options are possible. Saiga 12 with a 203? Niiiice.

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That depends on what you plan to attach it to.

Hmmm; kinda even across the board; personally, I want to add a 12" standard mount '203 to my arsenal. I sure as heck have the right platforms (20" A4, 14.5" M4). Maybe even go full-retard and get a KAC stand alone mount.

I am no fan of LMT, but I like the LMT stock system better:

FWIW, I'm just going off imperfect memory here, and I have no direct knowledge, but as I understand, the rail mounted version was designed to be used with the MRP, and requires MRP-esque rigidity if you actually intend to fire it more than a couple of times, and that other rail systems, particularly two piece types can be damaged by being used with the rail mount '203.  

~Augee

There are a handful of rails said to be good for the rail mount, DD, Larue, etc.

Postal is correct. There are plenty that'll work, but one must be selective.

This is the kind of knowledge I was hoping would get dropped in this thread before I dropped my money.

That almost looks like an M203 mounted to a grenade launcher...

Geissele?