Dear Marion,
You could ask a question for me to veterans who have been in Italy?
I love the m1 helmets and collect them, but there is a disagreement.
Veterans remember if they or their companions have never had a m1 front seam swivel bail in Italy in '44 '45?
Many of my friends here claim that there were never. Were all fixed bail!
Thank you very much,
Enrico
Enrico sent me a private PM. I have emailed this question to every WWII vet on my list. Let's see what transpires this time around. Happy to assist.
Front seam, swivel bale helmets appeared around September 1944 in the ETO (maybe even sooner).
I guess the same goes for the MTO.
New units and new reinforcements to the units already in the MTO must have worn those types already.
Rear seam, swivel bale helmets were never worn in WWII as far as I know.
Hope this helps.
Erwin
I remembered this link on our main site:
http://www.m-1helmet.com/
He has a lot of photos and info on his site. You can also contact him directly Enrico. I'm sure he could answer all your questions.
Here's a great page on another site:
M-1 Helmet Info
Hey Jeeps -I found this on that page:
LATE WAR M-1 HELMET SHELLS
M-1 Helmet (1944 - 1945)
Due to the profound problem of the brightness of the stainless steel rims, in May of 1944 the Army Service Forces requested that the problem be corrected. Until that point, other options to solve the problem had been implemented such as the use of sandblasting and utility tape, but these both were unsatisfactory.
Distinguishing features
In October 1944 the rim material changed from stainless to the same steel that the helmets were made from (Hadfield Maganese). Evidently, for some unknown reason, at the same time, the weld seam of the rim also migrated to the rear.
Note: I personally have found numerous rear seam WWII era shells with stainless steel rims, suggesting the existing stocks of stainless rims must have been used up even after the change was put in place
Thanks a lot for all the answers, I have always maintained, that certainly in the Gothic Line, were present m1 swivel bail, but my friends have always closed my mouth with phrases like "that's impossible!" 
Precisely for this reason I hoped in the memories of some veterans to prove that it is not impossible, on the contrary!
I have repeatedly tried to explain to them that the production of swivel bale, front seam i'ts started in September 1944 (if I remember correctly for a month) but it seemed to speak with the gods of WWII! 
Thanks again I will study all this stuff!
Add:
For dating I was referring to this site, has a very interesting list! http://www.hardscrabblefarm.com/ww2/dating_m1.htm
Ah, you now have some "ammunition" in your belt! 
Knowledge IS power!!!
So glad we were able to help you with your question today. This is fun!
BTW, my nickname on the forum is M1! 
Please not the difference;
Rear seam, fix bale helmets; used from August - September 1944 ETO (MTO maybe even a little later);
and
Rear seam, swivel bale helmets; in my opinion never used in WWII, only from around August - September 1945 (or even later).
What me personally is concerned;
If I want to make a D-Day display, I'd go for a front seam, fix bale helmet.
If I want a The Bulge display, I might go for a front seam, swivel bale helmet but I would prefer a front seam, fix bale helmet.
And if I would go for a Germany 1945 display, I might go for a front seam, swivel bale helmet.
In either case, I don't think it would have mattered to the GI what type his helmet was.
As long as it kept his head safe!
Erwin
Please not the difference;
Rear seam, fix bale helmets; used from August - September 1944 ETO (MTO maybe even a little later);
Rear seam, fixed bail?
I have not ever heard and I've never seen anyone either in photo, nor for sale ...
You got some pictures?
In either case, I don't think it would have mattered to the GI what type his helmet was.
As long as it kept his head safe!
Erwin
Thank You Erwin! My sentiments exactly. I started collecting WWII items only 5 years ago and I still don't understand how some people will pay such outrageous prices for helmets and etc. unless they were cursed with having too much money 