View Full Version : Transfer port interchange HW97

partime outlaw
15-09-2005, 11:08 AM
Could anyone make an interchangable transfer port fitting for the HW97, i would like to be able to interchange the size of the outflow so i can reduce the power quickly for garden prctice. If anyone has the tools and skill needed would you let me know. Thanks.

partime outlaw
15-09-2005, 11:54 AM
Obviously i would pay for the service :) All it needs to be is a top hat shape with reduced central bore made to fit what would be an opened port(to allow for wall thickness) and several such hats could be substituted for the required power.

15-09-2005, 12:55 PM
Sounds fiendishly complicated. You would come up against problems like piston bounce, etc. Playing with transfer ports is a black art, the secrets of which are known only to a few...! :D :D Try looking for a S/H pump up, like a Benjamin, or Sharp. Ideal for what you want.

partime outlaw
15-09-2005, 01:26 PM
I like the pump guns but this idea would work as you fit the top hat from the outside, this makes it simple. I just need somone to machine one for me.

15-09-2005, 01:48 PM
If you use transfer port size to determine power output of a springer,

firstly its going to recoil like a "female dog"

Secondly, you're going to have problems with sealing the breach,

Thirdly, you're going to bugger up a perfectly good rifle.

Just think about it, if it was going to be so easy someone would have done it long before now.

OK you might say that not everything has been thought of yet, or the best ideas are often the simplest, which may well be true but in this instance too many people have been fiddling around with, inventing, customising and generally seeking to improve air rifles for someone not to have tried this in the past and given it up as a bad idea.

just incase you do go ahead with this you should be able to order a new compression tube from Chambers Gun Makers ;)

partime outlaw
15-09-2005, 01:56 PM
It could be but i am pretty sure that you only get recoil problems with the port being oversized and just a reduction in power if the undersize is resonable. All i need is a brass top hat that fits over the metal portion of the transfer surface and snug against the seal, outside diameter 3.2mm inside 3, 2.9 and 2.8mm. It is just a top hat shaped peice of metal but i have no access to machine tools at present. If anyone can make it for me it would prove interesting to see how or if it worked :p

16-09-2005, 04:48 PM
you will get a lot of piston bounce with a reduced diameter transfer port, and the amount of reduction that you are talking about will not necessarily reduce the power as you will generate more heat on the compression stroke leading to an increase in dieseling and possibly higher power.

16-09-2005, 09:59 PM
Why not cut out some washers out of shim stock to fit behind the breech seal (with different size holes in ) another well known rifle maker does this to reduce the power of their rifles.
Washers do not have be to thick ,about the same thickness as a cat food tin is thick enough,which can be cut with a strong pair of scissors, Ron.

partime outlaw
19-09-2005, 08:21 AM
Thanks, that's an easy and cheap way to go so i like it :)