Merkel O/U chokes numbers?

I sent a message to Merkel asking about the choke(s) on an O/U I recently inherited. They responded with:

We could find out that the choke combination oft he O/U-Shotgun with serial number is ½ - 1/1.

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I assume "1/2" is modified? And "1/1" is?

I was hoping for a skeet or trap gun.

George P said:

1/2 is modified, 1/4 is IC, 3/4 is IM, 1/1 is full
M/F works fine for trap; can be a tad tight for skeet, so learn to run the gun,
or call Briley and have them install some thin wall chokes

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Briley?

George P said:

1/2 is modified, 1/4 is IC, 3/4 is IM, 1/1 is full
M/F works fine for trap; can be a tad tight for skeet, so learn to run the gun,
or call Briley and have them install some thinwall chokes

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I’ve heard of guys who prefer an upper modified and a lower full for trap. Is that common? Aren’t trap O/U shotguns typically 2 full choke barrels?

George P said:

Depends on which trap - US or International. Most US shooters shoot a single shot for trap singles and the double can be either M/F or IM/F with the tighter choke in the top barrel (on fixed choke guns)

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Apparently this Merkel has the tighter choke on the bottom. I assume there’s a barrel select switch on the gun. I haven’t shot it yet.

With trap, wouldn’t I want to fire the modified choke first, followed by the full choke? Hence, shooting the top barrel first? And aren’t you supposed to fire bottom barrel first?

BTW, isn’t a 26” barrel a bit short for a trap gun?
I was thinking more like 30”?

George P said:

Why do you assume the tighter barrel is on the bottom? Unless it was specially built for possible driven birds, typically the more open of two chokes is on the bottom and the tighter on the top.

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Just based on Merkel’s reply:

We could find out that the choke combination oft he O/U-Shotgun with serial number is ½ - 1/1.

Click to expand...

I’m assuming 1/2 refers to the over barrel and 1/1 refers to the under barrel.

I’m also assuming that in trap you want to fire the modified barrel first and then have the full choke barrel when you come back on that 2nd bird since it’s been traveling longer and is consequently further out.