WW1 Regt Uniform Identification please?

[ALAMO2008]

Photo taken in St Helens Studio in WW1
Can anyone identify the Possible Regt please?

[Viktoria]

I know little to nothing about uniforms really ,but something about this photograph that makes me think U.S.A. Despite the St.Helen’s studio.
Viktoria.

[Andy J2022]

Sadly he's not wearing any insignia which would tell us his regiment. He's a Lance Corporal who has earned one good conduct stripe (the one on his lower left arm) and was a marksman (the crossed rifles badge). This probably indicates he was in the infantry, but it's not a certainty as it just indicates a skill in shooting. The American army didn't wear good conduct stripes. Although there is an insignia on his buttons, it's not clear enough to identify. However we can rule out the Rifles and the Green Jackets as his regiment since they had/have black buttons.

What I can't make out is the symbol or whatever it is above his left wrist where it disappears behind his right forearm.

[still_looking]

Could the bit above his left wrist be a combination of the piping on a field service cap and part of a badge?

S_L

[ShaunJ]

Looks like he's wearing a blue patrol jacket so he's unusually well dressed for a WW1 soldier.

https://www.greatwarforum.org/topic/301118-blue-patrol-frock/

[Andy J2022]

Also known as No1 dress or more colloquially as Blues. However I would have expected him to have collar dogs or shoulder titles, but there appear to be neither.

[mmm45]

looks like a watch fob and chain  the stuff by his wrist