Hw35

[tuck1]

Ok, today's update so far. I obtained a pack of Araldite steel, and have painted the cylinder end with it. Once dry, I have removed the excess and refitted the piston, over lubed it to make sure it slides freely ( not under its own weight, but not far off) and re assembled. 6 ft lbs. tried the old spring yesterday, nearly maimed myself getting it in, 7 ft lbs.
Ps I tried the water bath yesterday but could find no sign of a leak.

I think the next port of call will be, as many have suggested, a synthetic piston seal and adaptor of some kind, any suggestions to which one may work best gratefully received. This one has a 3 mm transfer port.

If this doesn't work, I have no idea what comes next. A spring from a truck axle maybe..?

[I. J.]

Just a thought. Have you checked the barrel lock up? I once had a barrel lock up on an old '35 that was that worn that the 'wedge' wasn't doing its job properly and allowing the barrel to open very slightly on firing allowing air to escape around the breech seal area. Just check for movement between the barrel and the cylinder.

Like I say - just a thought.

[tuck1]

Thanks for the suggestion, I will investigate and report back.

[landymick]

Try the new spring plus a washer on the guide,i had one with an OX in it this only managed 4 ft/lb or so.This one has 4mm T.P in .22,also tried a spring from a German power rifle this had 26 coils & gave 5 ft/lb.
On this one i know the piston seal could do with replacing.Is your cylinder in good nick with no scoring?

[tuck1]

Hi Mick

The cylinder looks in good order, as does the leather seal, and although it does take a small amount of pressure to push it through the compression stroke, it isn't much. Judging by the fact that the gun probably hasn't been fired in a while, and was left uncocked, I'm guessing that the seal is fairly well sized to the cylinder? The cylinder does look to have cross hatchlings on it, I'm not sure if this was standard or this rifle has already been fettled ( unsuccessfully). I'm wondering whether I should try to lay my hands on some dri slide or similar, but somehow I'm thinking that this isn't really a lube issue, more a fundamental mechanical one. I read a really interesting thread on here by member "guzzidom" who had similar issues, I don't know if he ever did manage to up the power on the gun, and if he did, what the problem was.

Next stop, pre load washers and breech seal check. stand by...

[tuck1]

Well I've had the piston seal out and treated again overnight, then found it had expanded and was too tight in the cylinder. Sized it using a bulldog clip and then it was too loose in the cylinder and wouldn't hold air. Left it overnight, where it pretty well went back to the status that it was in before I started! I've relented, and ordered a synthetic piston seal and adaptor. In the meantime, with regard to the leaky breach seal, I've removed and re fitted the new breech seal, and can detect no play in the breech lock up area. I'm at a bit of a loss now really until my parts arrive next week. For a rifle that's only producing 5 ft lbs it's very heavy to cock too, but I'll persevere and see how I get on. Thanks for your continued help and advice.

Adrian

[Benelli B76]

Well I finished up cutting a couple of coils of f the spring, and reassembling the gun with some difficulty as there was still a couple of inches of preload. Gave the spring and piston a very light smear of grease, almost invisible. The gun was easier to cock, but still twangy, and after over 100 pellets it still won't group, and seems to be getting progressively more difficult to cock.more grease required? I am definitely thinking that I need a chrono of my own now, to get to the bottom of this, is there anything else I may be missing? Spring still too long?
I'd be grateful for your thoughts.

Two inches of preload sounds too much. I have just done a couple of HW35 rifles (see the one on "G96 best cold blue" thread ). The other I fitted a number 4 OX spring supplied by owner. I cut 3 coils off, heated and collapsed the end of the spring and ground it flat to make it neat. With this fitted it was giving 500 fps on the chrono with 16 grn pellet (too low). I stripped and dropped 3 standard thickness washers in the piston and regreased to get it up to 574 fps. Fair bit of resistance in cocking, but a nice solid sound on firing with no twang.

Baz

[tuck1]

What do you think is happening, piston rebounding off a wall of air that cannot escape fast enough?

I'm gradually trying to understand the physics involved.

[Benelli B76]

What do you think is happening, piston rebounding off a wall of air that cannot escape fast enough?

I'm gradually trying to understand the physics involved.

I am not sure what is wrong with yours, but what I said previously worked for me. Cut 3 coils off the Ox 4 spring and put some spacer washers in the piston and voila, 11+ ft lb with nice firing cycle. I have found that the HW 35 and HW 80 do not like a lot of preload. You should not have a great struggle to screw in the trigger block. The HW 80 is a honey to work on and very predictable. The HW 35 with the shorter chamber can be unpredictable and take some experimenting to get smooth satisfying power sub 12 ft lb.

Baz

[tuck1]

Well, the synthetic seal and adaptor have arrived today from John Knibbs, along with two more shims to replace the ones I have, erm, "modified". I've fitted it, whipped it back together and am getting a consistent 8 ft lbs. taking on board the opinions above, I think the wayforward now is to gradually shorten the spring, testing as I go, and see what it does to the power. I still have the square section one which came out of it if I go too far, and as suggested, some washers might do the trick. I can't see that the cylinder is still leaking really, after all I've done to it the holes must be blocked by now! could anyone point me in the direction of a test for a leaky breech seal? I'm sure I've seen a method somewhere using cig papers or chalk, but can't seem to find it.

Once I get the power where I want it, I'll start thinking about the firing cycle and noise....

Many thanks to all that have helped me so far

[I. J.]

Well, the synthetic seal and adaptor have arrived today from John Knibbs, along with two more shims to replace the ones I have, erm, "modified". I've fitted it, whipped it back together and am getting a consistent 8 ft lbs. taking on board the opinions above, I think the wayforward now is to gradually shorten the spring, testing as I go, and see what it does to the power. I still have the square section one which came out of it if I go too far, and as suggested, some washers might do the trick. I can't see that the cylinder is still leaking really, after all I've done to it the holes must be blocked by now! could anyone point me in the direction of a test for a leaky breech seal? I'm sure I've seen a method somewhere using cig papers or chalk, but can't seem to find it.

Once I get the power where I want it, I'll start thinking about the firing cycle and noise....

Many thanks to all that have helped me so far

Put this around the breech area as you fire a pellet into a safe back stop.

[kamag]

Well, the synthetic seal and adaptor have arrived today from John Knibbs, along with two more shims to replace the ones I have, erm, "modified". I've fitted it, whipped it back together and am getting a consistent 8 ft lbs. taking on board the opinions above, I think the wayforward now is to gradually shorten the spring, testing as I go, and see what it does to the power. I still have the square section one which came out of it if I go too far, and as suggested, some washers might do the trick. I can't see that the cylinder is still leaking really, after all I've done to it the holes must be blocked by now! could anyone point me in the direction of a test for a leaky breech seal? I'm sure I've seen a method somewhere using cig papers or chalk, but can't seem to find it.

Once I get the power where I want it, I'll start thinking about the firing cycle and noise....

Many thanks to all that have helped me so far

hi Tuck1
im also having similiar probs with a 35e i have just aquired it was doing 6ft lbs,

fitted a spare
synthetic sealed piston this then droped to 4.5 ft lbs with the same spring which was a
smaller diameter than an original and fitted into a sleeve .
i decided to try a sqaure section spring which required the use of a spring compressor,still only
4.5 ft lbs took 3 coils of and 7.2 took another 2 coils off 9.5 with hobby it would appear that
with a stiff spring not much preload works best eventually i want to go back to a smaller
diameter spring with a sleeve, this is a 1976 model i also have a 1986 one that run close
to 12 ft lbs with hobby just shows no two are the same
regards
les

[Rickenbacker]

Well, the synthetic seal and adaptor have arrived today from John Knibbs, along with two more shims to replace the ones I have, erm, "modified". I've fitted it, whipped it back together and am getting a consistent 8 ft lbs. taking on board the opinions above, I think the wayforward now is to gradually shorten the spring, testing as I go, and see what it does to the power. I still have the square section one which came out of it if I go too far, and as suggested, some washers might do the trick. I can't see that the cylinder is still leaking really, after all I've done to it the holes must be blocked by now! could anyone point me in the direction of a test for a leaky breech seal? I'm sure I've seen a method somewhere using cig papers or chalk, but can't seem to find it.

Once I get the power where I want it, I'll start thinking about the firing cycle and noise....

Many thanks to all that have helped me so far

Hello If possible, perhaps try to get a second opinion from a different chrono'?

The Combro is a good little device, but not always the most reliable where recoiling guns are concerned. And with it's close proximity to the muzzle, plus a blast of lube vapour from the freshly assembled gun... well, it's just a thought... It'd be funny if the gun was actually rocking along at 11 ft/lbs already!

If you can't think of another chrono to use, an alternative test would be to shoot at various ranges, and calculate approx' power by the trajectory.

Or, older members who still have their marbles may remember the penetration data for a yellow pages and/or metal dustbins.

[I. J.]

Hello If possible, perhaps try to get a second opinion from a different chrono'?

The Combro is a good little device, but not always the most reliable where recoiling guns are concerned. And with it's close proximity to the muzzle, plus a blast of lube vapour from the freshly assembled gun... well, it's just a thought... It'd be funny if the gun was actually rocking along at 11 ft/lbs already!

If you can't think of another chrono to use, an alternative test would be to shoot at various ranges, and calculate approx' power by the trajectory.

Or, older members who still have their marbles may remember the penetration data for a yellow pages and/or metal dustbins.

Good point regarding the second chrono. I didn't realise a Combro was being used.

Im one of the older members who has lost his marbles but I remember the pre chrono days when your ambition was to reach the Zoo in the Yellow Pages and the comment "It would go through a dustbin - IF I could hit it!"

ATB
Ian

[Rickenbacker]

Good point regarding the second chrono. I didn't realise a Combro was being used.

Im one of the older members who has lost his marbles but I remember the pre chrono days when your ambition was to reach the Zoo in the Yellow Pages and the comment "It would go through a dustbin - IF I could hit it!"

ATB
Ian

From the match cards pictured on your FWB 65 thread I noticed earlier - There's not much wrong with your hand/eye co-ordination Ian!

Another thought about the OP's gun - Is a 3mm TP correct for the leather seal HW35? I thought they were 4mm? Or did I dream that...

ATB - Phil