While we are on the subject , would no.4 mkI SMLE components fit in my case?
Went back and reread thread, I am not really sure what you mean by fit in my case. As far as parts compatibility, there are a few No. 1 MK 3 (aka SMLE) parts that will work with the No. 4, Mk. 1. A buttstock for the No. 1 for example can be altered to work in a No. 4 with some judicious wood working, on a lot of them. I believe that the buttstock screws are likewise compatible as is the buttplace with proper inletting and or shortening of the stock to do so if necessary. The barrel bands are not compatible and neither are most if not all of the screws as the Brits changed threading between the two different series. Basically everything in front of the receiver is not really compatible between the two series due to differences in the barrel, the nose piece cap in the SMLE, and the heavier barrel of the No. 4.
For folks not interested in Enfield nomenclature, please feel free to ignore the rest of the post.
BTW, a few folks are rather unforgiving when posting about a No. 4 SMLE which did not exist. The SMLE (Short Magazine Loading Enfield) is the earlier name for the No. 1, Mk. 3 and this was to differentiate it from the earlier Long Lee Enfield aka the Magazine Lee Enfield (MLE aka Emily). The No. 1 Mk. 1 had a long barrel based on its preceding black powder models and I believe that this series began in 1903. The success and desirability of the carbine length made the long barrels almost instantly obsolete and thus the No. 1, Mk 3 was born and converted during WWI to the newer No. 1, Mk 3* which simplified manufacturing for production during war. Later experimental models regarding Mk numbers were created up until the eve of WWII where the new No. 4 was based the last of the No. 1 series on faster production, better accuracy (heavier barrel and rear aperture sights), and using more modern materials.
Thus, if buying parts, make sure you get No. 4 parts rather than the generic Enfield type--if necessary, Stratton's book on the different parts for the No. 4 rifle has an exhaustive list with pictures of each variation of the No. 4 (a similar book exists for the No. 1 series). Regarding the trigger guard and forend, there is an updated No. 4, Mk. 2 which has a receiver mounted trigger block and some No. 4's were altered that way and will be marked No. 4 Mk 1/2 or No. 4 Mk 1/3 depending which model of No. 4 was converted. The Savage (and Long Branch) used an altered bolt release with a gap in the receiver rail near the chamber for snapping and unsnapping the bolt head for removal. These are known as the No. 4, Mk. 1* (the star denoting a minor alteration in the design). The only problem with some of these is that the rail cut has been known to break off pieces which generally makes the rifle unserviceable and why these rifles were among the first to be surplussed compared with that of the standard No. 4 bolt releases behind the receiver charger bridge. The parts are mostly the same between the No. 4 Mk. 1 and the No. 4 Mk 2, Mk 1/2 or Mk 1/3 with the exception of the trigger guard and the stock forend. You might be able to get the No. 4 Mk. 2 stock forend to work with the No. 4 with some woodworking knowledge as the rear inletting is different at the rear of the forend at the stock ring and the Brits added a recoil screw instead of the previous stock reinforcing plate used in older No. 4. This forend is only about 50 bucks or so from Numrich and they do have them in New Old Stock Condition. From the amount of inletting work that I had to do with the Long Branch No. 4 Mk. 1/3 that I restored, I believe that you could use one with minor alterations to the stock.
The key to using a new forend or even a new used one for any of the Enfield series is to properly seat the receiver recoil surfaces with the wood stock (called the draws)--gaps, wood rot/shrinkage/oil soaking, wear, improper dismounting of these stocks from the receiver can cause accuracy problems and stock splitting problems. Look up Peter Laidler's expert discussion and posts on the milsurps.com website in their Lee Enfield Knowledge library where he goes through step by step fitting of the stock to the receiver as well as other posts on fitting other parts. Laidler was a former armorer for the Brits and had extensive experience in refitting rifles for service and his techniques are strictly those used by the British military to restore the rifles to service by the book.
https://www.milsurps.com/showthread.php?t=16948 GunnyUSMC who has restored more than a few stocks to use posts on various websites can also point you to using some techniques to repair or fit a stock albeit not necessarily the British military way.
Occasionally, the P14 aka No. 3, Mk. 1 rifle which is a Mauser pattern type parts are sold as Enfield parts. So be careful buying from ebay/gunbroker sellers as they may not be knowledgeable.
One other option, which GunnyUSMC has undoubtably recorded in one of his famous detailed discussion threads, is to buy the forend tip of the stock replacement piece from Liberty Tree for about $10 bucks and splice the front end of your existing forend or another sportered version which tend to be quite cheap for the No. 4. It takes some epoxy, rod type reinforcement, etc. but can be done pretty cheaply and the splice can usually be hidden underneath the barrel bands. I once did a Krag, an Arisaka carbine stock, and a 1917 rifle to fix the sporter cut stocks and avoid the unobtainable/high priced uncut originals.