Opening up HW95k transfer port

[eyebull]

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).

[Shed tuner]

use a hand reamer.. start with 1/8" 3.2mm

3.4 / 3.5 will probably be optimal, and will prob give you around a foot pound

[Brano]

How about a calibre change to smooth it out. A replacement .22 barrel might prove straight forward.

[eyebull]

use a hand reamer.. start with 1/8" 3.2mm

3.4 / 3.5 will probably be optimal, and will prob give you around a foot pound

How much will each reamer take off in a go? Do I need to have one for each 0.1mm increment? Because that could get spendy...

How about a calibre change to smooth it out. A replacement .22 barrel might prove straight forward.

Already have a silky smooth .22 HW95 bought from a member here, however I much prefer .177 for hunting unless at fixed ranges (e.g ambushing at a feeder) because of the more forgiving trajectory. The trick is finding or fettling a rifle of reasonable weight that's as forgiving!
Should have got it in full length rather than Carbine tbh.

[Shed tuner]

How much will each reamer take off in a go? Do I need to have one for each 0.1mm increment? Because that could get spendy...
.

they have a lead in.. typically around 0.2 - 0.4mm. Imperial 1/8" reamers are dirt cheap on the bay. You can also get taper reamers, which are fine, but you have to go from both sides, and are not so good on longer ported rifles like a 95.

so basically you just buy a 1/8" and say a 3.4mm and you are covered...

[eyebull]

they have a lead in.. typically around 0.2 - 0.4mm. Imperial 1/8" reamers are dirt cheap on the bay. You can also get taper reamers, which are fine, but you have to go from both sides, and are not so good on longer ported rifles like a 95.

so basically you just buy a 1/8" and say a 3.4mm and you are covered...

Thanks for that, reamers now on the way. I'll report back with results once I get round to it.

[TORNADOS7]

Don't would be my advice, they need weight up front buddy, I had a mate machine up a weight to replace one of the hair curler sections in the silencer, made a world of difference to the accuracy...

Drop the short stroke, leave the guides in place, add weight to the silencer and set @ 10.5-11.0...

Ps, they're not much better in .22 either although they will shoot @ 11+ easier...