Leo III or Leo V

[Skolot]

Hello ! Please help me to identify this coin. And help me to understand the difference between Leo III & Constantine (Sear 1516) and Leo V & Constantine (Sear 1630). These types look similar, the only difference noted in the description is akakia held by Leo III & Constantine. I tried to search for examples and found a lot of coins without akakia, looking absolutely similar to Leo V, but attributed as Leo III. Are they all misattributed ?

[Obryzum]

Leo V.  The Leo III coins are more scarce. They also tend to have a more squat M

[Skolot]

Thank you Obryzum.
I see many dealers use this similarity to sell Leo V as Leo III 
Finally I have found on the internet an example where akakia is clearly visible. It is the main detail that matters, am I right ?

[Obryzum]

Other telltale signs include the break of the legend. The Leo III coins usually, but not always, break with ONS between the heads.  The Leo V coins usually break with SC between the heads.

If the officina is B then it is always Leo III.  

The Leo V coins have a legend that usually ends with a    The Leo III legends usually, but not always, end before getting to the  

Two examples of Leo III:

[Obryzum]

Another thing I have noticed is that the quality of the metal for the Leo V coins is different.  For some reason the coins seem to have more trouble developing a hard patina.  During cleaning it is very common to see copper exposed, as in the coin you posted at the top.  

[Quant.Geek]

There is a much easier way to tell a Leo III from a Leo V coin.  Aside from the legends, the coin is very much different.  For instance, in Leo V coins, there are no arms on either Leo nor Constantine:

Byzantine Empire: Leo V the Armenian (813-820) Æ Follis, Constantinople (Sear 1630; DOC 7)

Obv: LЄOҺ S C-OҺSC; Crowned facing busts of Leo and Constantine, each wearing chlamys
Rev: Large M; cross above, X/X/X to left, N/N/N to right, A below



whereas, in Leo III coins, both Leo and Constantine are holding akakai and you can see there arms:

[Skolot]

Thank you all ! Exactly what I needed.