Barrel housing SP20 RRS

To remove the barrel and barrel housing start by removing the magazine and grip assembly.
This is done by  unscrewing 1 screw in the grip and pulling it downwards.
Cock the gun, unscrew the 3 bolts in the front of the barrel, pull forward and remove. Pull the slide back, let it gently come forward until 6-8 mm before full close, pull trigger and set aside.
Never dry fire with slide fully closed.

The barrel housing serves several purposes.

1) Serves as an attachment for the barrel. The barrel is hold in the barrel housing by 2 clamping bolts on the side and 1 tapered allen head screw that holds the barrel in alignment.
2) Houses the 4 recoil weights and their springs

3) Attatch the front sight post.

4) Offer an attachment point (2 tapped holes) for additional counter weights

5) 2 recessed holes in which the return spring guide rods sit

4 different size allen head tools are needed to completely remove and disassemble the housing

From left to right:

Allen head size 3 mm (this one comes with the gun)

Allen head sizes 2,5 mm, 2 mm, 1,5 mm

Tools shown in there respective locations.

Barrel housing as seen from behind.
Top 2 holes and bottom hole are for housing mounting bolts.
4 holes around barrel retain the recoil weights and springs.
2 holes in the middle (approximately 4 mm deep) are for the recoil spring rods.
On top you can just see a few threads of the tapered screw that centers the barrel in the housing.
Behind it the front sight post is visible.






















Barrel housing front.
3 bolt holes for the housing mounting bolts.
hole in top middle is for removing or turning the front sight.
The front sight has 3 sides of different width. (4 mm, 3,7 mm, 3,2 mm)

Front of  barrel is up in picture.
Shows collar with tapered hole to center barrel in barrel housing.
Collar also holds recoil weights in barrel housing.

Close up of front sight post and tapered barrel centering screw.
Sight post dimensions are 4 mm, 3,6 mm, 3,2 mm
Several different posts with different heights and blade sizes are available.

Recoil weights and spring. (ruler in mm)
Recoil weight is 4,7 grams per weight.
I doubt if they are really effective, due to their light weight.
I know of one SP20 RSS user who replaced them by tungsten weights and used stiffer spring.

Clean the weight bores (in the barrel housing) with a cotton tip and keep the weights lightly lubricated (I use Ballistol)

One SP20 RRS specialist designed a new barrel housing which can house 2 big weights
with a weight of 33 grams per weight instead of 4,7 grams. 
(but as far as I know he is no longer making them)

Picture shows barrel collar holding recoil weights in barrel housing.

Underside of barrel housing with two drilled and tapped holes for weight holder.
The two barrel clamping bolts are also clearly visible.

Complete barrel housing and barrel.

Additional info and pictures:

It seems that for non RRS versions a light weight barrel housing is (has been) available.

Two extra weights are available.
A 20 gram weight thats mounted in a recess in the frame and a 50 gram weight that is
bolted to the underside of the barrel holder
 

External 50 gram weight

20 gram weight

Not all barrel housings are factory drilled and tapped for external barrel weight.
(this is a non RRS version) 2 screws are added by user