Weihrauch HW35 Model 'C' ????

[Hsing-ee]

Just seen this critter advertised in a 1980 copy of AGW. It was a model sold by Airgunaid of Chelsmford and seems to be a 'bitza'. I haven't heard of it before - is it a real HW model? I know that Airgunaid made rifles based on the Diana G80, is this one of their own or is it a genuine HW model?

The spec was this ...

a. 12mm scope rail (this is the old size, the 10mm rifles are advertised on the same page)

b. 22" barrel, presumably the same one as fitted to the HW35 Exports.

c. Standard beech stock (no chequering, grip-cap, no cheek-piece) with sling swivels

And most interestingly

d. 4mm transfer port

Can anyone care to explain? Anyone ever seen one of these - although it would look exactly the same as a HW35 Standard with a 22" barrel.

I wonder what the 'C' stood for? Custom? Weird as the rifle is standard-looking.

[fat man]

Hi yes i have that copy of agw too, from what i remember it was a standard 35 as you say fitted with a silicone spring and the transfer port resized, seems allmost a test run for the Vixen ! IJ and others please clarify for us.

[benchstop]

Eddie Barber did a 35 article from the same period, he mentions that earlier 35's had 4mm transfer ports.

atb Mike

[I. J.]

A bitza?

Early cylinders with the 13mm scope rails and 4mm transfer port with Export barrels and standard stocks. Perhaps part of a deal with Weihrauch?

ATB
Ian

[richywilk]

I think they were FAC only if I remember correctly

[Hsing-ee]

A bitza?

A non-model of something which is made up of bits of this an bits of that. BSA used to make some 'transitional' models which were like this.

The high-end bitza in the world of motorbikes is the Triton, a powerful Triumph engine in the taught-handling Norton frame.

[T 20]

Hi Alistair

Airgunaid and Optima as well as a few others advertised HW 35's with what was described as full power export 4mm transfer ports.

The standard transfer port being 2.8mm is half the volume of the 4mm transfer port.

Mike Wade in his experiments found that a transfer port of 3.175 mm gave the best power output.

In an Airgunworld article Venom said they didn't alter the standard transfer port size; so who knows.

My own 13mm HW 35 has a 4mm transfer port which seems a bit on the large size at 12 ftlbs (it worked well at 15 though )


All the best Mick

[Hsing-ee]

Yes 4mm would need to have a powerful spring and a tight-fitting pellet to make it work properly I think, and like you say, would make for an FAC level rifle. Might reduce efficiency with a weaker spring and make it harsh to shoot. Hmm. Maybe it works well with the leather piston washers as the piston velocity might be a bit slower?

I had a HW35 which had a tiny lip of metal on the transfer port, where the drill hadn't quite made it through. It must have occluded less than 10% of the passageway, and I removed it with a couple of strokes of a rat-tail file. It increased the power by 1 ft/lb!

I don't think I would mess about with transfer ports other than by tidying them up though.

[T 20]

Yes 4mm would need to have a powerful spring and a tight-fitting pellet to make it work properly I think, and like you say, would make for an FAC level rifle. Might reduce efficiency with a weaker spring and make it harsh to shoot. Hmm. Maybe it works well with the leather piston washers as the piston velocity might be a bit slower?

I found that a leather washer coupled with the 4 mm transfer port had so much lost volume that the piston slammed into the end of the cylinder.

I fitted an O ring piston head and increased the stroke on my 35 to reduce the effect of the lost volume caused by the 4 mm transfer port.
This is how I ended up at 15 ftlbs.

When I destroked the gun down to 12 ftlbs I ended up with piston slam if I used anything other than proper Wasps.

I really must build my 35 up with my spare 2.8 mm transfer port cylinder sometime for comparison with the 4 mm cylinder.


All the best Mick