Regged Carbine Shot Count.

[Bezzer]

I decided to convert my .177 S400 I use for HFT into a regged carbine as after trying others I much prefer the feel and balance of the carbine. I was going to do it by the book, well Robert Lanes instructions but had a few problems.
I hadn't used it for a few weeks when I started, didn't bother with a shot string/count graph as it was being altered so chopped the barrel and fitted the carbine air tube I'd got. Then did a shot string and it was only doing 640 ish fps usually does 780/11.3, I know shortening a barrel reduces the fps, thought 100 odd was a bit much but didn't read too much in it then. Decided to do the reg, enlarge the transfer port etc but when I came to test it was getting 610fps . Stripped it and found the firing valve was ridged and knackered, must have given up when it was left unused for the 2 or 3 weeks, Hindsight is a wonderful thing, I should have fired it before I started the alterations and would have realised the problem before I carbined it.
I made a new valve and shaft from delrin and stainless, put it back together and now back up to 780 fps, my problem is as I didn't get a proper shot count before it was regged I've no idea as to what I'm aiming for when I start messing with the exhaust valve spring pressure, hammer spring etc. Can anyone who has fitted the Lane reg to a carbine give me an idea as to what shot count they managed to get out of it so I've got a target number please? Don't think the delrin is going to last long so I've got hold of some Peek and made another valve to fit when I start testing proper.
As an aside I had quite a problem getting the reg to seal, kept getting a small weep from the vent hole, polished and polished until I realised the tube was welded and not seamless tube as I expected, the weld wasn't flush and could actually feel the depression/slot in it with a fingernail, took ages to get it smoothed out. This is a 2015 carbine tube, my original 2009 full length tube appears to be seamless can't see any sign of a weld line in it, cost saving?

[TenMetrePeter]

Are you sure Air Arms made the 2015 tube? Have you asked them if they use welded tube now? That would be a crazy weakness at the most stressed place and would be visible through the blueing on the outside.It would blue a different colour at a weld..
on the other hand a drawn tube may have some ridging and the standard design doesnt call for a smooth turned interior. It only needs enough metal to cut two threads for the end pieces. Maybe they changed tube suppliers.

[Archer50]

My regged .177 carbine gives about 75 regged shots with the Altaros reg set at 100 bar. I have not enlarged the transfer port, but I shortened the hammer spring by 1 coil and adjusted to 775 fps with an AADF by adjusting the valve spring. Before cutting the spring I was only getting about 45 regged shot, which was about the same number as shots in the sweet spot before installing the reg.

Alan

[Bezzer]

Ta Alan, it's a Lane reg but you've given me a target.
As regards the tube, checking the markings it seems it should be seamless as it's got a "DOM" mark which denotes Drawn Over Mandrel so it seems the groove is a broached line. I know they put a groove in the end fittings as a burst safety feature. If this is a genuine part, and I've got no reason to believe it isn't, seems like they broach a groove down the whole length as well now.




1st pic is the 2015 carbine tube at the top, bottom the 2009 full length tube
2nd pic is the groove, goes the full length of the tube




edit- having trouble with the pics, I'll have to use another machine shortly.......sorted

[Roger5]

DOM= Date of manufacture, that what I think, could be wrong.Rog

[TenMetrePeter]

If that groove is now standard its going to upset Robert Lane! Could be a controlled burst line but it will also increase stresses unnecessarily. I would get AA involved directly for an answer in case that's a rogue cylinder.

[Bezzer]

DOM= Date of manufacture, that what I think, could be wrong.Rog

Yep, more than likely it is that and just a coincidence that it's also the acronym for Drawn Over Mandrel with regards to seamless pipe.

I'll contact Air Arms for the definitive answer regarding the groove.

[Roger5]

DOM= Date of manufacture, that what I think, could be wrong.Rog

Yep, more than likely it is that and just a coincidence that it's also the acronym for Drawn Over Mandrel with regards to seamless pipe.

I'll contact Air Arms for the definitive answer regarding the groove.

Just had a look in a handbook and, yes it's date of manufacture. Should learn to trust myself a bit more Rog

[Bezzer]

Spoken to Air Arms, as far as they are concerned there should be no groove in the cylinder, if I send it off to them they will examine/test it.
Also spoken to Robert Lane, he's not overly surprised at the state of it, he's has loads of very poorly finished and grooved Air Arms cylinders though probably not quite as bad as mine from my description, I'm sending him the photo for info. Apparently it's a lottery, he can have AA cylinders in a decent state that don't take much work to make the reg seal and then others that are a right pig and take forever to smooth/polish. His UTube video on how to sort minor persistent vent hole leaks was prompted by the hassle he's had with Air Arms ones though he falls short of actually mentioning them in the video.
Mine is now holding air so I'm going to leave it at that for now, not worth the hassle/cost of sending it back etc if needs be I'll get another cylinder as and when. I'd just advise anyone thinking of regging whatever AA model checks the cylinder first to see how good/bad it is on the inside as to whether you are up to getting it smoothed to an acceptable level. If I was starting from scratch again I'd have JB Welded the groove first then polished it up.

[Bezzer]

Just to round this off, the breathe hole weep reappeared. Stripped it down again, filled the groove with JBWeld for a few inches in to clear the reg area. Sanded down beautifully to leave a perfectly smooth tube, Everything back together and no leak, held 190 bar for a few days with no problem. Played about with hammer springs and the firing valve preload and it's running at 770fps with 8.4 Exacts for 70 shots, 3.5mm transfer port with screw fully out, I was going for 780fps but this is close enough for now.
Sent Robert Lane a pic of the cylinder groove and to quote his reply " bloody hell that's the worst one I've seen".
As an aside when I said I said I'd shortened my barrel from full length to carbine I did it from the muzzle end not the breech my reasoning being I didn't want to disturb the set up of a nice straight shooting barrel. Did seem to be a bit of choke when I pushed a pellet through but that soon disappeared when I chopped 4 inches of the end Cut the step back on the end and crowned it with a touch of a hand held countersink then grinding paste. Been to the range a couple of times and it's shooting spot on. Done it before with a choked barrel years ago (RWS/Original 45) with no problem, my take is if it's a "decent" barrel to start with losing the choke makes no odds. Only problem is there's currently loads of iffy ones, BSA/Gamo and Weihrauch 100 ones for a start.