Port sizes Weihrauch HW 77K

[MddogHutty]

Hi guys just wanted to ask I have fitted everything brand new to my 77k new seals spring top hat and guide kit. But still firing under power by more than 100fps - 2ftlbs.
You guys in the US seem to be very knowledgeable when modding your port sizes. So would like some advice on what I could get away with modding mine, buy what size could I enlarge mine too. To gain that extra power I am missing. I believe it is 2mm now at what size could i enlarge it too to gain that extra power, if anyone could help with this please leave a reply thx.

 

[JohnL57]

I don't know anything about modifying the port sizes-I'd hesitate to modify from stock unless I felt sure about what I was doing as going back from too much of an enlargement might be difficult. You may get more power by adding a spacer or two to get more preload on your spring, some kits come with washers to fine tune velocity. It's also not unusual for the speed to come up a bit as the the parts wear in.

 

[MddogHutty]

The john already done that I may off found the answer to my question when adding a new piston seal I didn't know after installing it that too put your finger over the transfer port if it doesn't slide down by the pistons weight the seal needs a slight sand it should slide down without a problem. I'm going to check to see if it does that as when you installing it was tight. So hoping that maybe the problem if not I'll try a new seal before going down that road. Has I have already used preload washers so will have to see. I now know the optimum size is around 3.0 to 3.3 if the article was right that I read.

 

[scrane]

You're only getting 10 fpe? I'd be surprised if your TP is only 2mm. I don't think I'd mess with the TP. Weihrauch has been making this gun for a long time and they should know what they're doing. I too tight seal sometimes reveals itself as a "honking" noise while cocking.