Late Roman Bronze Coins

Hello ladies and gentlemen.
Not very optimistic but could you try to rule down the mintmark and ruler for this worn FTR?

20 mm 3.13 g
On the obverse I can see CONSTANTIVS (this doesn't help much) and the mintmark - can't distinguish clearly, appears like CAI but this doesn't make any sense.
Many thanks in advance.

I believe it is Rome 258. RIC lists several possibilities for the workshop—E,S,Z

Constantius Gallus
A.D. 352-355
D N FL CL CONSTANTIVS NOB CAES; bare headed, draped & cuirassed, B behind bust.
FEL TEMP REPARATIO; Soldier spearing fallen horseman, Γ in left field.
In ex. R wreath [?]
RIC VIII Rome 258

Thank you for your help, much appreciated.

The posters on FORVM do not seem to be able to see a B behind the bust. If it is indeed a B, my attribution must be right.

For me it looks like an S and this doesn't make any sense.

By the way I hope it is allowed to post the same subject there as well, I am not trying, by any means, to contradict you, but I know  LRBs in poor condition can be quite a challenge. 

Of course you can post your coin anywhere...it is important to get a second opinion, especially as I can be (and have been) wrong.

Yes, S is not possible, but a poorly preserved B can resemble an S. There is also the mintmark, without even being specific, it seems there are three objects, which fits for Rome, but not other mints. As far as the gamma being too big, you can compare with other examples. What one wants to see as an M in the left field, is what I see as a gamma and the spear.

below are some examples of Rome 258 for comparison

Your examples made me 99% sure you are correct.
Especially no 2 and no 3.

Quite frustrating with those ones from Constantine era, I am a beginner but I find these ones the most difficult to solve.

I recently bought a lot (and a very interesting one!).
I was hoping there are not many FTR coins as I know they can be frustrating. Fortunately there was only one more, funny, in a better conditon (slightly).
Legend break - so Constantius II. But mintmark is unreadable, because of the coin shape, I can see a Gamma in the left field in the reverse.
Is it OK to post the pics in this thread?

Sure, post it here

There it is, thank you for all your help.

There is a Δ behind the bust and it looks like a Γ in the left field of the reverse, though it is hard to be sure on that. With that combination of marks, the choice of mints is either Rome or Constantinople. I can't make out the mintmark, though Constantinople is the most common and would be something like CONS[?], with question mark substituting for whichever workshop A, B, Γ  etc.

Thank you again.