New hunting permissions beckon and while I have absolute confidence in the LGV from 10-40 yds it's a fat old lump and no good for a walkabout, nor am I over keen on attaching sling mounts to the competition stock. The ideal would be a light to medium weight springer in .177 which was meant to be my 95k.

However was never happy enough with the accuracy or useability of my HW95k in .177 to hunt with it; Goes without saying that it got a basic clean, deburr and relube, and I added a TBT shortstroke kit which did improve things slightly, but I think I'm going to take the next step and open up the transfer port, as well as fit a newer style piston seal.
It's do or die - if it all goes pete tong then I suppose I'll have to sell the leftovers on here and buy a HW99S!

Would appreciate any and all advice as to correct procedure for opening up the port without access to lathes and mills, hand and power tools only - was going to use a drill to open it up to 3 or 3.2mm, and then a hand reamer to open it up to 3.5. Is this a terrible idea? Will that leave burrs on the inside of the comp chamber? If so what is the best way to deburr? Should I expect power to increase substantially? (lack of power is not currently an issue, if anything I could lose half a ft/lb).