Remington 1187 'O' ring spec's

[FatCatsDad]

I'm looking for the specs for the gas system O ring.
The size is

15/16" ID, 1-1/16" OD, 1/16" Width​

It's a Viton material size # 021 but this size is available in different hardness grades.

It's available in a 75A and 90A .

Will either be fine ?

 

[Winz]

I don't think you'll see much of a difference in use of either Duro rating.

 

[FLHTCUI]

There is a member here that sells both 12 and 20 gauge O-rings for 1100 and 1187's.
You can buy from him or go to your local hydraulic shop with you current O-ring in hand and have them sort it out for you.
For less than a double double or a Eightbucks cafe latte mocha you can have a mitt full (lifetime supply) .
Or enough to outfit your shooting buddies at your next Turkey Shoot.
Meaning you will Never have to worry about oem factory Duro ratings again.
Rob