thanks!

Bush rifle has an 18" barrel and no mount for optics. Just a regular M1A with a shorter barrel.
I like mine

Isn't the scout a 16" barrel and have a rail for mounting optics, forward of the receiver........

Scout Squad/Bush are the same rifle with the  Scout having the forward (scout) scope mount.  SOCOM puts you into 16" territory, witht the SOCOM II being railed.  Doesn't really matter, you'll end up trying to buy two in each flavor.

what he said

Personally, I like the Scout's rail for an optional red dot if you aren't going to put any magnified optics on it, but mine will probably be coming off since I put an ARMS 18 on it when I decided to try for a long range stick

Don't they have a different muzzle device?

I know the socom uses a diff gas system, i am talking about the scout and bush rifles

IIRC the only difference, in regards to the muzzle device, between the standard and the bush/scout is the required lack of a bayonet lug. Can't remove the gas plug with the lug in place.
I could be wrong.

The M1A Scout Squad has a muzzle brake and a barrel rail mount.  The M1A Bush (no longer in production) had a flash suppressor and a few also had the bayonet lug.  The M1A Bush model did not have a barrel rail mount but there were both fixed and folding stocks for it.

An advanced collector and I have most of the SA, Inc. catalogs and price lists from 1973 to the present day.  I've put together several data spreadsheets of SA, Inc. products.  From the spreadsheet on factory catalog numbers for M1A rifles, here's the different Scout Squad and Bush models that have been sold at one time or another.  M1A-A1, Bush, and Scout Squad all indicate an 18 " barreled M1A.

AA9101M1A-A1 / M1A-A1 Bush with USGI stock
AA9102M1A-A1 / M1A-A1 Bush with commercial walnut stock
AA9103M1A-A1 with oversized walnut stock
AA9104M1A-A1 with oversized brown or camouflage fiberglass stock
AA9104M1A-A1 / M1A Bush with black or mossy oak fiberglass stock
AA9105M1A-A1 with fancy walnut stock
AA9106M1A-A1 Bush with black synthetic stock
AA9108M1A-A1 with birch M14E2 stock
AA9109M1A-A1 with walnut M14E2 stock
AA9110M1A-A1 / M1A Bush with folding stock
AA9115M1A-A1 with Shaw standard walnut stock
AA9116M1A-A1 with Shaw E2 walnut stock
AA9116M1A-A1 Bush with black wood laminate stock
AA9117M1A-A1 with camouflage USGI fiberglass stock
AA9119M1A-A1 with USGI fiberglass stock
AA9121Scout Squad with USGI stock
AA9122 Scout Squad with commercial walnut stock
AA9124Scout Squad with mossy oak fiberglass stock
AA9126Scout Squad with black fiberglass or polymer stock
AA9127Scout Squad with black wood laminate stock
AA9129Scout Squad with olive drab polymer stock