What makes a rifle to be a Block 0, 1, 1.5, 2?

It's different for each weapon system and each upgrade increment.

You'll need to be more specific.

What is different? Can you give an example for any specific weapon system - M4???

The SOPMOD - Special Operations Peculiar MODification program was an accessory kit to outfit the M4A1 Carbine used by SOF.  The original program has been around since about '94-'95.  

It has been being continually upgraded as technology availablility changes.  Originally there was no "Block" or "Incremement," those terms started being used to describe newly released items that began to directly replace earlier generations of the SOPMOD kit.

"Block 1.5" tends to be used to describe Phased Replacement era-M4A1s - M4A1s that continue to use the KAC M4 RAS, while otherwise using Phased Replacement or Block 2 accessories.  While the SOPMOD program was originally envisioned as being used solely for the SOCOM M4 (M4A1), as always, once the items get to their units, there's little control as to where or how the items get utilized.  

Not only do SOPMOD components show up on CQB M4s (M4A1 CQBR), they end up on various other weapons systems like the SCAR series, various M14 variants, machine guns, ect.  

At its base, it's simply an accessory kit issued to SOF units to outfit their weapons as needed for non-conventional operations.  Many of the accessories now used even by conventional forces are modelled after the SOPMOD program, but are not "SOPMOD."  A basic inability to understand the difference between conventional forces adding accessories to their weapons (for example, the AN/ PVQ-31B TA31RCO-M4CP Marine Corps ACOG is not a SOPMOD item) has led to some confusion, however SOPMOD is and has been a SOF specific program.

"Original" SOPMOD M4 (No "Block" or "Increment"):




SOPMOD Block 1:




SOPMOD Block 1 Phased Replacements and Block 2:




~Augee

Augee, since you love this stuff and probably have the info readily available, what is the approximate timeline that each Phase took place? Just for curiosities sake.

Augee, do you pretty much have 1 of each now?

Thanks Augee. More questions....

Does the SOPMOD M4 or the SOPMOD Block I M4 make any specifications to the kind of rail system? I understand the Block II specifies DD RIS II, does the original or the Block I make any such specifications?

There's not necessarily an exact timeline - older components are still out there and used.  Plus, a lot of units individually purchase items and accessories for their M4A1s that are not necessarily SOPMOD components, but nonetheless commonly used.  

For all intents and purposes when GWOT started the Block 1 components were on line, and early photographs of SOF in Afghanistan are mostly using what would be considered "Block 1" SOPMOD M4s.  

A lot of units quickly picked up EOTechs, however, and the 551 at first, and later the 552 were almost "de facto" standard in a lot of a photographs.  

Phased Replacement components started showing up in pictures around the 2005-2006 timeframe, and many co-existed with a lot of unit purchase and Block 1 stuff.  

RIS II equipped CQBRs were pretty common by late-'08, IIRC, across all components, while RIS II equipped M4A1s have been being sighted in pretty common use since about late '09, early '10 with a couple of units, but almost completely absent from others that still use RIS or RAS equipped M4A1s.  

A lot of times you still see much older components mixed with the newer ones, too, though.  For example, from what I can see, the TA01NSN is still fairly popular, both with and without the MRD.  

The above slides are not the entirity of all of the components, either.  There were a lot of other little modifications that fell under the umbrella of "SOPMOD" enhancements, or at least were included on SOPMOD PowerPoint slides .  Things like enhanced charging handles, McFarlane gas rings, "O" rings, ambi-safeties; MRD enhancements for the 4x DOS, ect.

And no, I do not yet have a clone of everything.

The original SOPMOD rail system utilized the KAC M4 RIS.  

The RAS was developed at the request of the Army, because it was felt that the top rail attachment needed to be improved for mounting aiming lasers.  SOF seemed to have no problem with it, but SOF is generally better about maintaining their weapons.  Without knowing for certain since we're not in the heads of the decision makers - but I suspect that the "problems" with the RIS had more to do with it being easily user serviceable than with it not holding zero.  At the time user unfamiliarity with the top rail and potential misinstallation / messing with things they shouldn't be would make the RIS intractable for conventional Army forces.  

A lot of SOPMOD M4A1s are shown using the RAS, but many recent pictures show the RIS, too.  I would suspect the RISs already in the system stayed in the system and continue to be used, but a lot of RAS have been purchased, too.  Also, a lot of M4 Carbines come from Colt these days with KAC RAS already installed from the factory - and probably M4A1s as well.  No one would practical would bother changing either one out for the other (with the exception of rabid clone builders ).  

~Augee

Thanks Augee. Your knowledge is unsurpassed  

One other thing I am wondering about. Why did the Phase II program go with the Insight weapon light instead of the Surefire Scout?

+2.

Augee, would you consider a SOPMOD M4 clone, or Block I M4 clone, a rifle with a M4 CAR FSB with a Larue or DD Omega (or Omega X).... rail system?

Most wouldn't. The rail and stock are two of the defining characteristics of the platform. Most everything else is end user configurable, but once you start swapping the rail it ceases to be a clone and just becomes a cool build.

A "clone?"  No.  Potentially a hell of a nice rifle, definitely.

The only real exception being the use of an Omega 7.0 to build an AFSOC replica, since one unit seems to have purchased Omega 7.0s along with several other "non-standard" accessories for their M4A1s.  

I've seen military rifles with LaRue rails as well - however, in my opinion only - I would consider a "clone" to be a replica of a military weapon - whether speicifcally "cloning" a photographed rifle exactly, or a "representative" clone using issued and/or common parts.  We've gone over it several times in the various clone threads - but I tend to think changing out rail systems that require an armorer install from what's "issued" makes it difficult to retain a "clone" status, since it would be difficult for most end-users to simply "swap" a FF rail system.  They would at least need to make a special request to the armorer, or use their own personally owned upper.  Now, if you want to build a clone of a rifle from a particular photograph - then you can simply say you're cloning *that* rifle.  

I don't think clones are the only way to build or set up rifles - if for no other reason than military weapons are often configured for very specific military applications - for example, if you're following the M4A1 thread - the buttstock GPS issue.  Some miltiary end-users have a need and desire to place a hand-free GPS on the stock of their weapon that is totally irrelevant to most kinds of HD, SD, or carbine class / LE applications, and may actually be counter-productive to those roles.  Also, my feeling is that much of the EOTech / Aimpoint debate about battery life is based in a difference between civilian / LE mission profiles and military ones.  

If you're a crazy history freak like me that likes replicas, clone away - but if you want a weapon that is specifically mission oriented, it might not always behoove you to look at military weapons as a "model" for configuration.  

As for why Crane went with the Insight instead of the SF?  Who knows.  The military's procurement decisions are not always explicable.  

It could have to do with lower profile, incandescent performance versus the LU60 module on the Surefire Scout, IR filter compatibility, compatibility with existing PEQ tapeswitches and the dual switch - or even politically / financially motivated, maybe Insight said they'd give 'em a better package price for lights and lasers versus just lasers.

I chose it because when I got it, the Insight was the only dual switch available, and the M3X the only light that could use it.  If the Surefire dual switch had been available, I might've stuck with SF lights - I already had an M600C at the time.  

~Augee