If you take a look on my other post about the l119a1, you will see the sfw differs to other armalite weapons, like the m4a1. As it has a 16 inch heavy barrel and an old car-15 style stock.
Now time for parts.
For this build I would recommend a G&P m4 or a CA m4 due to the fact , their well built and they will accept most of the parts no bother. Personally i went with an ICS m4 as i like the split gear boxes. however they are far from the most hassle free donor weapon and also you don't have the option to fit a pre-made l119a1 or c8 receiver
16 inch barrel
First option is to get the whole barrel itself. Army code and Pro Arms makes offerings , personally I have the pro arms , they are available on a number of Hong Kong retailers like Airsoft Global and Ehobby.
Second option is an extension for a 10 inch cqb weapon. A number of people have gone down this route and picked up extensions for a number of places , for one i know a member on a UK airsoft forum makes correct 6 inch extensions for 10 inch barrels
Stock
The stock seen used on the SFW is an old car15/m733 style stock like this one below
Easy to pick up second hand on airsoft forums , it is for some reason difficult to buy these from a retailer now. these are often seen combined with a butt pad for car-15 stocks often tied on with cable tie , Guarder and G&P make a nice replica with ridges in the back. (Butt pads available on Ehobby and WGC and AirsoftGlobal , Im not sure which UK retailers stock them.)
Storm Grip
While not vital, it has been seen on many a real picture and adds to the over all look , this one above is meant to fit systemas, and both the systema and AEG versions are available from number of UK and HK retailers
Front Sight.
Army code made a batch of these a few years ago , but they are like hens teeth now and the most feasible option is to miliput your m4/m16 front sight.
L119a1 Receiver
Again not vital but totally adds to the look to have correct trades
G&P and Dboys both make offerings for v2 gearboxes , other options is just to have a blank receiver or paint out your trades as there is real steel weapons knocking about with blank receivers and even c8a1 receivers , with ics weapons you cant have trades and I mentioned above , also for systema users , it is possible to get a blank receiver engraved. Another way to combat the wrong trades is to attach a ready mag , personally I think they look horrid.
RIS
The Ris rail seen used on L119a1s and CQBs is the KAC ris
Loads of manufactures make these , including G&P , CA , ICS , JG , Dboys among others. And you can pick one up in a retailer of you choice more often than not , as I have an ICS rifle I have an ICS ris.
Sights
first of is the ACOG , the brits were issued the TA01 style acog without the fibre optic and with the battle iron sight on-top
Tonnes of people make these , including G&P and Ares , Also Ebaybanned have some nice offerings , Jodo has one and it's an excellent sight for the price. It is also possible to get away with the acog with fibre optics.
Acog and Doctor , this is a fancier option , but in my opinion the most practical.
Again a few people make these but ebaybanned again has some good offerings.
Protective wing mounts
A few acog and doctor combos have been seen with wing mounts to protect the doctor red dot.
Rudy on a UK forum got a big batch of these made , although these are available on ebaybanned again , I would recommend getting yours from rudy.
DIS
These are like hens teeth again , I know some people would go wild for one , there was a batch made if I recall right but they went for 100 quid each. A US retailer also has a similar sight in stock but it does not have the diemaco markings.
Other Sights
Also Eotechs and Aimpoints have been seen in action with the uksf lads on the CQB rifles in the famous Iraq set of pictures.
Flashhiders and Suppressors.
Along with regular m4 style birdcage flashhiders , Vortex flashhiders and FH556 have been seen used on SFWs
The FH556 is meant to be used in conjunction with the surefire 556 suppressor
And the surefire suppressor
Mike on again a UK forum made a few batches of these.
Accessories
PEQ Boxes. Both the PEQ2 and the PEQ15 have been seen in use on the l119a1 and c8 CQB
Loads of manufacturers make the peq2 as a battery box option , and ebaybanned have some excellent peq15s on site with lasers or lipos inside them.
Vert Grip
A number have been seen in use on the SFW , including Tango down Grips and Troy style grips along with the standard KAC vert grip and the fancy Bipod grips now used with the British SA80.
Again a few replicas have been made , but getting your hand on a real one wont be much of a problem at all.
Flashlights
It seems the Surefire scout was issued with SFWs , it's not hard to pick up a real one and a few replicas have been made
Also seen in use is the llm01 taclight also used on the SA80 , I have heard vfc made a run of these and also there was a private run of replicas too
UGL
Last but not least is the UGL , and the general consensus is if you're not built like a tank , its very cumbersome. A french forum did supposingly a good guide on how to fit a star one to your SFW but my french is poor and I cant find it at this very second.
I will be adding more and more to this post over time so keep your eyes peeled