Neil strips and re­places the in­side work­ings of a friend’s Fein­werk­bau Model 300S - part one

Neil Price takes on a com­plex top qual­ity tar­get ri­fle

Air Gunner - - Contents -

The Fein­werk­bau Model 300S is an early ‘re­coil­less’ spring- pow­ered air ri­fle that was used mainly in the 10- me­tre card, and six- yard bell dis­ci­plines. They op­er­ate on the slid­ing rail prin­ci­ple. The first model in this range was the model 150, which was in­tro­duced in 1963 and ran till 1968 when the model 300 was in­tro­duced. Next was the 300S in­tro­duced in 1969, and from 1972 to 1984 both the 300S and 300SU were pro­duced in tan­dem un­til they were su­per­seded by the sin­gle- stoke pneu­matic model 600.

Al­though this is the 300S the same pro­ce­dure is ap­plied to the whole range of Fein­werk­bau slid­ing- rail tar­get ri­fles.

A friend of mine with whom I have been shoot­ing six- yard bell tar­gets for over 20 years, ac­quired this ri­fle in ex­cel­lent ex­ter­nal con­di­tion, but he couldn’t seem to get con­sis­tent scores with it so he asked me to have a look at it for him. I told him that I didn’t think it sounded right, so told him to get a kit of re­place­ment in­ter­nals ready for me to strip it down.

It seems that it had been many years since this had been stripped, if at all from brand new, so I did a quick 10 shots over the chrono us­ing un­weighed R10 .177 flat­nosed pel­lets at 8.2 grain, av­er­age weight, to see how it was per­form­ing.

I First re­move the diop­tre sight and put it some­where safe be­cause they are ex­tremely ex­pen­sive to re­place. 2 I marked the po­si­tion of the rear diop­tre sight with a pen­cil line so that I could re­place it in the same po­si­tion. 3 When do­ing the chrono’ string, I no­ticed that there was no com­pres­sion of the breech seal when cock­ing the ri­fle. There should be com­pres­sion be­ing felt on the cock­ing lever from about this po­si­tion, but there was none. 4 Re­move the front screw in the accessory rail and the rear trig­ger guard screw and the ac­tion can be lifted away from the stock. 5 I al­ways use a shal­low tray to keep all the bits and pieces that I re­move dur­ing the strip­ping of a gun. This saves me from search­ing all over the work­bench for scat­tered bits and pieces when re­build­ing it. 6 Un­hook one end of the small spring on the end of the guide bar hous­ing. 7 Care­fully prise off the larger ‘C’ clip on the guide bar hous­ing cross- pin with the tip of a small screw­driver and re­move the cross pin. These clips can spring off un­ex­pect­edly and travel long dis­tances, so be ex­tra dili­gent when re­mov­ing them. 8 The two guide axle pins are held in place by small ‘C’ clips in thin grooves in the axle pins. 9 Once the ‘C’ clips have been re­moved, by gripping the ex­posed end with pli­ers the axle pins can be pulled out. These are hard­ened and ground, so pli­ers will not mark them. 10 By lift­ing the rear end of the guide bar to release the two dim­ples, the end block and rear axle pin assem­bly can be slid out of the end of the ac­tion. 11 The whole guide bar can now be re­moved from the ac­tion. 12 Loosen the two screws re­tain­ing the trig­ger mech­a­nism onto the ac­tion. 13 Re­move the two screws that hold the trig­ger and ratchet mech­a­nism to the frame. These can be very tight and I had to re­sort to the old ‘span­ner on the screw­driver’ trick to get the torque re­quired to undo the slot head screws.

The whole trig­ger/ratchet assem­bly can now be lifted clear. 14 Take out the cock­ing lever ful­crum pin. 15 Un­hook the cock­ing link hook from the com­pres­sion cylin­der. 16 Care­fully re­move the ‘C’ clip from the spring clamp pin. 17 Re­move the pin from the in­side of the ac­tion. 18 Re­move the safety spring from the in­side of the ac­tion.

19 Now the spring and safety plunger can be re­moved from in­side the ac­tion. 20 With a 17mm A.F. span­ner, loosen the pil­lar nut/shoul­der screw. 21 Hold the ac­tion up­right and ex­ert down­ward pres­sure. Take out the shoul­der screw, wash­ers and sad­dle piece. There is not much spring pre-load pres­sure on these springs, so it is quite easy and safe to do with­out us­ing a spring compressor. 22 The spring pre- load pres­sure can now be let down, al­low­ing the trig­ger block to exit the ac­tion. 23 Note the pis­ton lock­ing plate and the filler piece that is lo­cated in a slot in the end of the trig­ger block. 24 Now the main­springs, com­pres­sion cylin­der and pis­ton can be re­moved from the ac­tion. The pis­ton was ini­tially stuck at the end of the com­pres­sion cylin­der. I had to poke a thin length of dow­elling through the trans­fer port and gen­tly tap the pis­ton down the com­pres­sion cylin­der. 25 There should be a pis­ton buf­fer in the end of the pis­ton. 26 As can be seen, there is not much left of it. It has com­pletely dis­in­te­grated. 27 This is how the rest of the re­mains of the pis­ton buf­fer came out. Need­less to say that where it was fit­ted had to be cleaned out scrupu­lously. 28 There is no seal as such on these pis­tons, but a pis­ton ring, the same as in your car. This pis­ton ring had a baked on de­posit on the out­side and was stuck fast in the pis­ton ring groove.

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