I have been offered this M1928A1 Thompson for the sum of 500€ (about 655USD).
Should I jump on it ? I was planning to build a M1911A1 to go along my 1991A1 but since I have seen it....
but I am concerned by the rear sight: unprotected & can't be adjusted...or am I just paranoïd ?
Well, I don't know the laws where you live, but here in the USA a legal registered 1928A1 SMG starts around $12-15 thousand bucks for a run of the mill specimen and gets up into the stratosphere for rare variations or unissued examples.
The rear sight like that worked fine on the M1 version issued during WWII, they were bullet hoses not sniper rifles. If you don't care about keeping it original a Lyman adjustable unit runs around $350-500 here.
Gabriel7384, I'd gladly pay 500 euros for an original 1928 thompson if I could own it legally. The rear sight can be replaced with the adjustable ladder style for about $150-$180 (USD). There are 4 rivets that attach the sight that will need to be removed on your rear sight, and replaced with new ones if you go this route. It's sad to think the people of the country that made that thompson can't legally own it anymore (not here before 1986) because of our restrictive gun laws. Here's a pic of the adjustable rear sight I put on my 1927. It's an original rear sight I purchased from sarco 1928 Thompson Lyman Adjustable Rear Sight I bought mine off of gunbroker for $150, but it came from sarco.
Like Kernel said that stamped rear sight is common, I wouldn't worry about it.
Since your lucky enough to get one at that price, and if you really want one, I'd get it.
"Government is not the solution to our problem, government is the problem" Ronald Reagan
Wow, prices on the Lyman sights have went way down, last year or so they were almost as much as the parts kits!
Kernel, the price drop was the only reason I bought one. I saw them for cheap last fall at the same time the wife was asking what I wanted for an anniversary present.