truckcop

good choice

Aftermarket stuff. Stick with OEM.

As to the hammer travel, with the trigger group out of the receiver, that's normal forward travel. With the trigger group removed, DO NOT pull the trigger and let the hammer go forward on its own. Like the AR15 lower with the upper receiver removed, you could cause some damage. Heating the receiver to remove the tube is highly unlikely to have damaged it.

Had one back in the day. Useless appendage. Save your money. Or use it to buy more ammo.

Only patterning it off your own shoulder will answer your question. Armchair answers? Not so much.

No

I've hade a couple of the GGG's installed for at least 10 years now, if not more. I don't remember even getting a spring from GGG back then. As I recall, I used the OEM.

If it's a "custom" gun, there's no telling what you'll get. If the trigger group has been futzed with, try replacing the springs with OEM and see if they will do better. If a lighter recoil spring was installed to be more "reliable" with lighter ammo, try switching back to OEM on that as well. On several occasions I watched Tom Knapp shoot extremely fast splits (no I didn't have a timer but I know what I saw) with his bone-stock M1's and M2's. Ten hand-thrown clays requires a fast action. Among other things. Just curious: What are you shooting that calls for less than .2 splits with a shotgun?

Yes, they were offered in wood-furniture hunting guns although the 21" versions were probably less common than the longer ones.

Just me, but I prefer the Nordic Components button which is round. I've got the GGG on a couple but due to the rectangular shape it's vulnerable to getting hit on an angle that can loosen the stud attached to the release bar since it's only a press-fit. I don't see the Nordic button on their website any more but they appear to be available on ebay and other sites.

Since the barrel you have and the barrel you want are designed for different receivers I doubt you'll have much luck coming up with someone to trade with. Your best bet is to sell the GR barrel and try to buy the one you want. I've actually had a bit of luck in past years buying a couple of M1/M2 barrels at reasonable (relatively) cost off GunBroker but that's hit-or-miss. The next best thing would be to sell your GR M2 and buy a standard field M2. Good luck.

Setting aside the Covid/BidenCrap inflated prices, that's a "want-to-sell-it" price rather than a "look-what-I-have" price. Entirely reasonable.

Is there not a choke in the barrel you can compare others to? From Briley's website, a comparison of Benelli chokes: https://www.briley.com/c-262-12-gauge.aspx

Nope, you'll just have to live with it until you get a new stock. I tried all sorts of "remedies". Nothing helped.

I shot a bunch of it back in the day. As I recall it worked quite well in my M1's and I seem to remember it was very clean ammo. I tried to buy more but it had disappeared. I think I have one unfired shell on a shelf somewhere.