I`ve finally found time to pop my delrin compensator on my budget Thompson and its made all the difference. The drum mag looked odd combined with the original fore end, now it looks a lot better. Installation was simple, cut the foresight pins off with a small kitchen knife, pop the comp on and screw in the grub screw to make a mark. Remove the comp and make a small dimple hole with the knife tip in the fore end for the grub screw to locate in, then pop the comp on again and do up the grub screw. 
The british thompson was The M1928 not the M1A1, the M1928 had the cutts compensator, the M1A1 which was used by the US military didn't have the cutts compensator. 
The British M1A1 didn't have the Cutts though.
No M1A1, regardless of British or not, was built with a Cutts compensator.
The British used the 1928 in its various standard or militarised versions for all infantry and homefront use before the STEN was invented. The M1A1 (as well as other US supplied weapons) was used by the Commandos and other such special forces.
A Proud Member Of 'Team Spleen!' who play mainly at Gunman Airsoft, Tuddenham, Suffolk.
that first picture shooting out the window looks like a 1928 upper receiver with cocking handle on top but with the m1a1 barrel and fore grip,not my specialist subject of course.
armoury
m1a1 Thompson,sten mk2,mp40,stg44,sterling,mk2 bren gun,lee Enfield no4 mk1,Mauser Kar98, Walther ppk,smith and Weston m10 and Mauser m712
Give me a big enough hammer and a place to stand and I could fix the world.
i'll kill a man in a fair fight or if i think he's going to start a fair fight or over a woman or.......
a problem shared is a problem halved ,but an advantage shared is no advantage at all
if a job's not worth doing then its certainly not worth doing well
that first picture shooting out the window looks like a 1928 upper receiver with cocking handle on top but with the m1a1 barrel and fore grip,not my specialist subject of course.
Correct, it's a 1928. Not all have the cutts compensator.
How do we know if the one pointing out the window has a cutts or not the end of the barrel isn't in shot.
Its interesting to see the tankies using the m1a1's I was always conviced us Brits only used the M1928.
Also the M1928's used by us Brits had both the straight and vertical grips.
The top pic looks like an M1928A1 to me. Horizontal fore grip and simple "L" rear sight on a 1928 receiver.
I can't see if the barrel is finned, but my Thompson barrel drawing shows finning and compensators as options, but not interdependent.
My source is revealed in this thread:
viewtopic.php?f=13&t=11842
The compensator is drawing number 5564369 "COMPENSATOR, RECOIL".
What that won't tell you is the modifications I make so they'll fit an M1A1 front end.
Hello there
Doe,s any one have a cutts compensator for Thompson m1a1 for sale if so call me on 07842436674
Thanks
Glenn
Oddball1953, check out this thread in the Sales-section. He makes some great looking compensators! 
