Air Gun Home :: View topic

Alstone · Moderator & Site Supporter

Twinmaster Power Mod part II
These mods will work for both Co2 and PCP guns. All the mods need to be done to get the maximum power. My twinmaster Action with all these mods puts out a max of 575fps and an average of 525fps over six magazines on a reasonably warm day

The first job is to alter the ports on the Twinmaster valve, as supplied the port holes are round and have sharp corners and the valve itself is very hard so to do this job you will need some emery string 1/16 dia, put the valve in the vice as shown use a piece of heavy card between the valve and the vice jaws then using the emery string carefully emery away the sharp edges on the ports, be very careful not to catch the sealing rim on the valve, emery the ports until they look like the photo.

Next make a 8mm dia packing washer 5mm long with a 4mm hole, this can be made from nylon, or brass, then fit on to the hammer spring shaft.

he last job is to increase the weight of the firing pin hammer head this is to prolong the opening time of the valve. The weight will need to be made out of steel slotted out as per photo and fastened on using a grub screw and Locktite, the size in not to critical but no bigger than the one in the photo.

Have Fun.

AL

AirGunEric · Site Admin

Very nice. Smile

Did you measure the output before doing any mods to see how much you gained overall?

Alstone · Moderator & Site Supporter

Yes the output before was peaking about 515fps and averageing 475fps over 6 magazines, again on a warm day, the tests for the latest power mod were done at an outside tempeture of 18C in bright sunshine, every shot was Chronographed with 15 seconds between each shot.

AL

AirGunEric · Site Admin

The hammer weight you added- why such a "custom" look to it- the cut-outs/rows in it? Was this just for appearance or were you aiming for a specific amount if weight? Is there a specific amount of weight that works best on the Twinmaster hammer?

Did you use some sort of cold-blueing method to color it- and if so- how did you like the end result?

And lastly (I think!)- how much of a difference in the gun's Co2/Air consumption was there after the mods?

Alstone · Moderator & Site Supporter

Hi Eric
The "look" of the hammer weight was not designed it is just what I finished up with, this is the maximum amount of metal you can get in the space available and the reason for this is that I originally was going to drill a hole through the hammer to fasten the weight on but the hammer is harder than I thought so I had to clamp the weight on, the problem is that you need the weight to be solid enough so that it does not spread when you tighten it up, the hammer inparts quite a lot of energy into the weight and this comes to an abrupt stop every time you fire the gun and unless it is fastened on very securely it will be following the pellet down the range, I did try a weight half the size of this one and it worked alright but it was to flimsy as for the groves they are just to stop your finger from slipping off the hammer. The blueing this was done with a gas torch but not very well as it was bright sunlight at thr time and I could not see the colour change properly, I do have some cold blue but to use it the metal needs to be scrupulously clean for the best results. As for shots per capsul it is about 50 I work on a pressure drop of about 10% ( 550fps down to 495fps ) this depends on air temp if you let it vary much more than this I need to adjust the sights on the gun for hight which is a bit of a pain, plus the pressure drops off rapidly after 50 of so shots.

AL