What's the best glue or whatever to fix this please ?

[StanP]

You can try J-B Weld. Very good product.

 

[HuskyDude]

Like others have said... WGP in Edmonton is your best bet.
But if you're like me and you want to see if it can be repair.
If the pieces fit together perfectly, I'd use some small stiff steel wire, an appropriate size drill. Drill a couple holes through both pieces insert the wire and use slow cue GB Weld on all.
Used this method on a few high stress items and they're still good today.

 

[smellofspentcasings]

Lag bolts and baling wire.

 

[Odinson]

Bust a few other things so it makes the shipping werth while.

I don't think so, they are off my shopping list unless I can't find it anywhere else. The shipping in this case was well over half the cost of the part. It could have easily been shipped by letter mail rather than taping that little plastic bag to the bottom of that huge cardboard box.
But I guess some staff are just not hired for their smarts!

 

[Deathrawt]

I’d just get the part you need from WGP and be done with it
I would still try to fix/ reinforce your broken one to see if it holds up
Worst case senerio you have a spare one to use if the repaired one fails
Shipping costs unfortunately are what they are
I remember paying dlask 30 bucks shipping for a tm22 charging handle, ridiculous but it is what it is

 

[Keller]

There's been a ton of suggestions here. If you're going to attempt to glue, you absolutely have to know what type of plastic it is. Use the best product available for that specific material and keep your fingers crossed.

 

[Can-down]

One thing I seem to recall with these plastic parts on this era of shotgun is that not only do they crack like that they also seem to curl and change shape. The clamping and adhesive needs to over come this pressure as well.