Quote Originally Posted by Blackmax View Post
Crikey, a lot of different suggestions on here.

The source of inaccuracy could be down to a number of things but most importantly, if it was at one time very accurate, without having to keep cleaning the barrel it'll be possible to return it to its former self.

Firstly let me say that a so called fussy barrel as they're described isn't a good barrel. A barrel should be able to shoot a number of pellets accurately but may have a preference that'll give supreme accuracy.

Let's start with the silencer, the HW version, a market leader, as others have said shouldn't bend, they're robustly built. Any damage would be evident on the 1/2 unf thread end by way of indentations. The silencer can be easily checked to see if pellets are clipping, remove the muzzle end with a 7mm Allen key. Inside are three chambers separated by metal washers, easy to take out and put back. The central hole is designed for 177, 20 and .22 so the former will have the greatest clearance.

The barrel; HW have recent history of producing poorly finished examples with rough internal finishes and crowns. Things just don't seem to be the same as when the Weihrauch's we use to know we're made in West Germany. The reason this causes inaccuracy is the rough finishes collect lead deposits. A proper barrel tune can often sort this out.

The internals; inaccuracy as your experiencing could well be caused by power fluctuations a chronograph would show this. The inlet valve could cause this if the ball bearing was sticking in its O ring seat. The piston could also be sticking. Dirt in the regulator washers can also cause power fluctuations. Issues with the dump valve would result in air loss down the barrel, so unless you're experiencing this it can be ruled out. A strip, clean and O ring chance will sort this as long as there's no damage.

The back block has a couple of possible causes, the first is the hammer sticking due to over zealous factory use of poor quality grease. Another possibility but a bit of a long shot is the cocking arm lever which could be slightly bent preventing a full seal with the breach. Again, a strip clean and check everything is geometrically correct will sort this out.

If of course there is a couple of these issues they could add up leading to the inaccuracy.

If you wish your welcome to pm me to discuss.

BM
Thank you for your comprehensive and informative post.

Given the previous 18 months extreme accuracy, I think it reasonable to assume that the barrel did not start out being poorly made. I finally checked the moderator myself. I could see no build up of lead nor any signs of pellet clipping. It was confirmed by exchanging the silencer for a brand new Huggett model; which made no difference to the poor accuracy issue. Additionally the gun was fired without any moderator and the shotgun pattern was still evident.

I could not get several series of ten pellets to show any substantial fps variations nor was the muzzle energy unexpected for the pellet weights and recorded velocities. With no power fluctuations, I am at a loss as to how I can understand the mechanism by which the pellets are not being delivered as expected. I think a full service is probably called for because after 18 months of weekly use, the gun could probably do with it.

When I removed the barrelled action, there did not appear to be any impediment to the hammer by way of a surfeit of grease. The cocking leaver appears to be the correct shape and is very smooth in its action. Thanks for the heads up about the breech not being sealed correctly with an out of true cocking lever.

Thank you for your kind offer of a PM conversation. I don't want to waste your valuable time just because I know SFA about guns. I believe the gunsmith (where the gun is was delivered) is a member of this BBS, so he may be able to further shed light on the issue for the benefit of the membership.

My short term answer is to wait and see what is revealed. I suspect now that a dirty barrel is still the culprit in some way that I do not understand as yet. I think some lead splash has attached itself to the rifling and is imparting a twist to the pellets. This would account for the random hits. I will try and film them in slow motion after I get the gun back.