Switching cylinders on Steyr LP10 (and more)

[nc513]

Well, how about that? I managed to make the classic mistake of not unscrewing the air cylinder _completely_ before retightening it. Sure enough, the green O-ring on the LP10's "nipple" now looks rather butchered indeed.

Since the LP10 handbook doesn't seem to contribute much useful information at all (on any subject), I'm hoping that some TargetTalker(s) would like to help me clear up a few things once and for all. Maybe I'll even be able to avoid making any further equally stupid, unnecessary mistakes.

1. How do I remove the damaged O-ring? Do I just pry it off, or do I have to perform some more advanced surgery on the nipple?

2. Is it safe to unscrew a cylinder at _any_ time, even if the pistol has just been cocked (but not fired)?

3. If I cock the pistol but leave the cocking mechanism slightly open so that I can dry-fire, what has happened in the pressure chamber and what will happen when I pull the trigger? At the end of a dry-firing session, should I fire a "real" shot (so that gas is released) before putting the pistol back into its case?

4. When you're attaching an air cylinder to the LP10 and hear a faint 'tic', your mission is accomplished. Is this assumption correct?

5. To keep tightening the cylinder even after you heard the 'tic' (despite the increased resistance) would probably be quite a bad idea. But what is it you might damage? The cylinder's threads, the nipple's threads, the nipple's green O-ring? Which is the most fragile part and how easily does it actually take a beating?

6. Also related to air cylinders: What's the best method for attaching a SCATT sensor to an LP10? There doesn't seem to be much free space between the cylinder and the barrel.

That's all for now, I believe. Many thanks!

[The Doctor]

I have added some notes by your questions - hope they help

Lee

Well, how about that? I managed to make the classic mistake of not unscrewing the air cylinder _completely_ before retightening it. Sure enough, the green O-ring on the LP10's "nipple" now looks rather butchered indeed.

Since the LP10 handbook doesn't seem to contribute much useful information at all (on any subject), I'm hoping that some TargetTalker(s) would like to help me clear up a few things once and for all. Maybe I'll even be able to avoid making any further equally stupid, unnecessary mistakes.

1. How do I remove the damaged O-ring? Do I just pry it off, or do I have to perform some more advanced surgery on the nipple? it takes time and patience, but its best to carefully cut the old one off with a sharp blade and the carefully thread the new one over the reg nipple (the bit with the thread on) - a little bit (and I mean a little bit) of moly will help.

2. Is it safe to unscrew a cylinder at _any_ time, even if the pistol has just been cocked (but not fired)? just dry fire the pistol - you can't really do any damage.

3. If I cock the pistol but leave the cocking mechanism slightly open so that I can dry-fire, what has happened in the pressure chamber and what will happen when I pull the trigger? At the end of a dry-firing session, should I fire a "real" shot (so that gas is released) before putting the pistol back into its case? Nothing has happened to the pressure chamber yet, as air stays in the reg irrespective of the dry fire or 'live' fire - simply pushing the breach forward engages the firing mechanism. You don't need to fire a live shot after training.

4. When you're attaching an air cylinder to the LP10 and hear a faint 'tic', your mission is accomplished. Is this assumption correct? tightened until hand tight so that the cylinder bottoms out on the base of the reg - any tighter and you might run into problems.

5. To keep tightening the cylinder even after you heard the 'tic' (despite the increased resistance) would probably be quite a bad idea. But what is it you might damage? The cylinder's threads, the nipple's threads, the nipple's green O-ring? Which is the most fragile part and how easily does it actually take a beating? you will struggle to do any real damage unless you cross thread the cylinder or get mole-grips on the cylinder to tighten it (not recommended) - as said before, tighten until the cylinder is secure and you should be fine

6. Also related to air cylinders: What's the best method for attaching a SCATT sensor to an LP10? There doesn't seem to be much free space between the cylinder and the barrel. there is plenty of room, but I would recommend getting a spare cylinder if you do a lot of scatt training as the clamp can leave faint marks.

That's all for now, I believe. Many thanks!

[FredB]

3. If I cock the pistol but leave the cocking mechanism slightly open so that I can dry-fire, what has happened in the pressure chamber and what will happen when I pull the trigger? At the end of a dry-firing session, should I fire a "real" shot (so that gas is released) before putting the pistol back into its case?

I've never seen anything written about this, but I do have a concern here. Maybe Scott, or someone else knowledgeable, will correct me if I'm wrong. When the gun is cocked, the valve striker spring is compressed. If you then only dry fire before putting the gun away, that spring will remain compressed. Therefore I always do fire one live shot (without pellet) to release that spring tension before I store the gun. I doubt it would matter much for a brief storage period, but it could matter if the spring was kept compressed for weeks. At least that's my theory.

FredB

[The Doctor]

I've never seen anything written about this, but I do have a concern here. Maybe Scott, or someone else knowledgeable, will correct me if I'm wrong. When the gun is cocked, the valve striker spring is compressed. If you then only dry fire before putting the gun away, that spring will remain compressed. Therefore I always do fire one live shot (without pellet) to release that spring tension before I store the gun. I doubt it would matter much for a brief storage period, but it could matter if the spring was kept compressed for weeks. At least that's my theory.

FredB[/quote]

The theory is sound but the mechanics of the actual firing mechanism mean that nothing is still 'under tension' if you just dry fire the pistol. I can check with Harry Preston the official UK importer but I am sure he will say the same thing :-)

Lee

[Gwhite]

1. How do I remove the damaged O-ring? Do I just pry it off, or do I have to perform some more advanced surgery on the nipple?

You "just pry it off", but VERY carefully. Using any tool harder than the metal underneath is asking for trouble. Any scratches on the seating surface of the O-ring will create a slow (or not so slow) leak. Carving a tool out of reasonably hard plastic works. Depending on how small the O-ring is, sometimes a wooden tool will suffice. Even a sharpened toothpick can do the job if you can stab the ring & pry it up enough to get another tool underneath it. Plastic tweezers can be useful. The best thing I've found is a set of oversized plastic dental picks. Midway sells them as cleaning tools, and they are also very handy for scraping the accumulated gunk out of a pistol without fear of scratching anything.

I used to make oceanographic equipment in a former life, and I've seen what happens when O-rings fail. Imagine a lot of expensive electronics filled with salt water (that's if it doesn't sink & is unrecoverable).

O-rings are odd, in that they seal at high pressure only if they seal at low pressure. They aren't like a gasket, which has a lot of mechanical force pressing them onto the sealing surfaces. The slightest bit of dirt or a scratch on the sealing surfaces of an O-ring can cause a low pressure leak, and they will never seal. It they hold at low pressure, the geometry is such that the high pressure makes them seal tighter. A perfectly ordinary O-ring will seal against 20,00 PSI or more if things are clean, properly lubed & the seats are machined right.

A LITTLE bit of grease helps, but with a compressed air gun, you need to use special O-ring grease or silicone grease. You basically want to get a very thin film (not enough see other than a shine) on the O-ring. Any more than that can attract dirt & cause leaks.

[FredB]

The theory is sound but the mechanics of the actual firing mechanism mean that nothing is still 'under tension' if you just dry fire the pistol.

Not so. On any CO2 or CA pistol with dry fire capability, you can feel the different lengths of spring travel needed to dry fire versus live fire. Once you cock the gun, the spring is at maximum compression and the gun is capable of either dry fire or live fire. If you engage dry fire, the valve striker travels only a short distance before it is stopped by a mechanism that does not allow it to hit the valve, i.e. the dry fire mechanism. At that point the spring remains partially compressed, relative to its more relaxed length after a live fire. It may not be significant - hence my question to Scott - but there is a difference.

FredB

[The Doctor]

Agreed FredB there might be a marginal difference, but surely if it was a significant difference the manufacturers would have mentioned it somewhere in the operating manual. I will try to get clarification from Harry on this one :-)

Lee

[luftskytter]

In addition to the above, most PCP or CO2 guns have a gasket (O-ring) which seals the pellet probe. This will tend to get deformed if the probe is closed during storage. I don't have a Steyr, but most guns are best stored with the cocking mechanism partially open in "mid" position to ensure a tight seal when the probe is pushed forward.

In most guns this will also leave the springs in a relaxed position and also make it easy to see that the gun is not ready to shoot.

[luftskytter]

Just another detail:
I once forgot to screw the aircylinder of my MG1E completely in before a shooting session. There wasn't any trouble: the cylinder was locked in place by the pressurized O-ring and there was no leakage. But the connection was elastic! The assembly wasn't stiff and solid like it would be with a fully seated cylinder. I guess this would affect the behaviour of the gun just a little bit. The point of impact on the target would probably shift slightly. Maybe just noticable for a better shot than me? I didn't notice before we finished shooting.......

[pilkguns]

leaving the gun cocked does put additonal stress on the striker spring.
You should also always unscrew the cylinder when yuo are not using the gun to take pressure out of the reg to save those springs and seals. You just need to ensure that you when do decide to screw it back up tight, that you first remove it all the way, or else you have the problem of the first poster, with a pinched o-ring that is ruined.

[luftskytter]

leaving the gun cocked does put additonal stress on the striker spring.
You should also always unscrew the cylinder when yuo are not using the gun to take pressure out of the reg to save those springs and seals. You just need to ensure that you when do decide to screw it back up tight, that you first remove it all the way, or else you have the problem of the first poster, with a pinched o-ring that is ruined.

No disagreement here;
I just try to get the best of both worlds:
I leave the gun semicocked (if your model allows it) to avoid squeezing the probe-seal without putting stress on the striker sping.
I've also made a C-shaped disk which fits between gun and cylinder, so I can leave the cylinder mounted securely on the gun, but without openng the valve or pinching the O-ring. This way I don't need a thread protection cover. Some makers sell these....
I've got one more of them so I can store the spare cylinder together with the filling adaptor.

[The Doctor]

leaving the gun cocked does put additonal stress on the striker spring.
You should also always unscrew the cylinder when yuo are not using the gun to take pressure out of the reg to save those springs and seals. You just need to ensure that you when do decide to screw it back up tight, that you first remove it all the way, or else you have the problem of the first poster, with a pinched o-ring that is ruined.

This is in complete contradiction to what I have been told by Steyr and their official importer in the UK??

Information to the contrary from Steyr has also been posted here:

http://www.airgunbbs.com/forums/showthr ... r+cylinder

Lee

[luftskytter]

Just a moment: before we get excited here, don't forget that there are some different guns involved here and in the linked discussion.
I said I shoot a MG1E, and there was a Röhm mentioned. We may be a little off topic since it all started with Steyr.

If you read carefully, you'll see that I don't cock the hammer for storage, just lift the lever enough to take pressure of the bolt seal: no strain on the spring. HAve to admit I don't know whether you can do this with a Steyr, but I know it's possible with many other AP match pistols.

Regarding the cylinder, this doesn't worry me much, and in the short term I often leave it attached. For long term I normally want to see the cylinder valve closed to avoid loss of pressure, and this means partly unscrewing or completely removing the cylinder. Most of you guys have a spare cylinder, so you gotta do this anyhow.........

[pilkguns]

Information to the contrary from Steyr has also been posted here:

http://www.airgunbbs.com/forums/showthr ... r+cylinder

information ALLEGEDLEY from Steyr was quoted there.

Steyr will not tell you that the best thing for the longevity of your regulator is leaving it pressurized. The may tell you that if you are shooting regularly that you will the o-rings out from use (abrasion) before pressure deterioation, which is true but for most basement shooters, the reg o-rings will die from pressure before abrasion issues.

http://pilkguns.com/bio-scott.shtml

[The Doctor]

Information to the contrary from Steyr has also been posted here:

http://www.airgunbbs.com/forums/showthr ... r+cylinder

information ALLEGEDLEY from Steyr was quoted there.

Steyr will not tell you that the best thing for the longevity of your regulator is leaving it pressurized. The may tell you that if you are shooting regularly that you will the o-rings out from use (abrasion) before pressure deterioation, which is true but for most basement shooters, the reg o-rings will die from pressure before abrasion issues.

http://pilkguns.com/bio-scott.shtml

Scott, I have had the same information in an email from Steyr and from the Official Importer in the Uk - sorry, I am not trying to be difficult, I am just trying to clarify what is the best option for Steyr shooters.


Lee

[pilkguns]

I'm not trying to be difficult either, just stating facts. I've known Harry and his family for many years and likewise Steyr personnel for going on 20 years. I don't believe either would have told you that the best course of action is to leave the regulator pressurized all the time, i.e., the cylinder being screwed on all the way. They may have told you it would not make much difference, as i indicated in my earlier post, but they could not have told you that it was the proper thing to do.

If someone was pinching the o-ring as this post started out as, then yep it would have been better to have left it better pressurized than pinch the o-ring. Is it better to properly unscrew the cylinder completly and rescrew it on? You betcha.