Crosman Icon

[avator]

I always bump test after hammer spring and trigger adjustment but I have to admit, I've never bump tested and uncocked gun.

[Rat Sniper (AKA: PaulT58)]

I a little confused on how an uncocked gun can even fire.  If it's not cocked then there is no tension on the hammer spring and nothing to release to impact the valve poppet if it's not cocked.  Maybe I'm missing something here...

[avator]

Paul, think hammer bounce.

[Back_Roads]

 Must be it uses a heavy hammer like the QB's either enough free flight when bumped to cause enough momentum to open the valve, or too much hammer spring tension on the poppet.
 Would not be a bad idea to test this on guns that have had valve / hammer spring mods.

[avator]

If I'm understanding this right, it can't happen with a cocked gun. The sear has the hammer locked in place. The trigger has to be pulled to release it onto the poppet. Now, adjusting the trigger too light is a complete different monster. A good bump would release the hammer. But in this case, it almost has to be the hammer bouncing off the hammer spring when the gun is dropped allowing it to free fly into the poppet. I would even venture a guess that if you dropped it hard enough the sear would catch the hammer and the gun would be cocked... I don't recommend dropping the gun hard enough to test that theory. 

In my opinion there are two scenarios that could cause this issue.
1) Too much preload on the hammer spring whereas a good bump would crack the poppet open.
2) Too much free flight allowing the hammer to bounce off the hammer spring and free fly into the poppet and crack it open when dropped.

[avator]

I bet a TSS or a BStaley oring stack would fix it. Both would need to be adjusted correctly.

[Rat Sniper (AKA: PaulT58)]

That makes more sense, but as James pointed out, it would have to have a pretty heavy hammer to overcome the tank pressure to open the valve!  I wonder if it does the same think regardless of the tank pressure, i.e. a full 3000 psi fill v. a low fill of 1500 psi or less?

Fortunately, most magazine fed air guns should have a pellet in the chamber after the last round has been shot, so unless the cocking lever is opened enough to cycle another round, there should only be air coming out the barrel when this happens on an uncocked air rifle.

[avator]

I'm finding it hard to believe that it's releasing enough air pressure to equal a full powered shot. The lack of a pellet in the barrel providing resistance to the air escaping the barrel will make the "crack" louder. Think the sound of a dry fire.

[nervoustrigger]

The hammer bounce analogy is correct.   It’s a weak strike...not much air released.  At least it was on mine with an almost fully charged reservoir. 

I haven’t had the hammer out but this behavior and the normal shot cycle both tell me it’s pretty heavy, and/or the poppet is a hard material that’s easy to knock open. 

[avator]

I would even bet this is not the only gun that this could be done with. Like I said, I never have bump tested an uncocked gun.

[K.O.]

I bump tested uncocked on some of my 13xx carbine builds because of using weak valve springs...

[NonGrata]

The weather was finally nice enough to take the ICON out and shoot today.  For some reason the trigger doesn't engage all the time.  About every 3rd or 4rth shot I'll cock the gun and nothing.  If I cock it a second time it will shoot but of course I need to remove the magazine when I do or I'll have a double feed.  Is anyone else having this problem?  Is there an easy fix or should I just send it back??

Part of the sear is extremely rough and is the cause for the "phantom cocking". It gets hung up in the reset cycle and the hammer gets locked in place but the sear isn't set all the way so it won't fire when the trigger is pulled. Once the area is filed and polished it cocks without fail. Obviously this is going to be a problem for the average consumer.

[NonGrata]

Received my 2 ICONS  yesterday 1 in .177 and 1 in .22.  Barrels look better than most have posted so I aired both up to 3000 psi. Without gun cocked if you set gun down semi hard on buttstock end they fire. If gun is cocked it does not do it. Is this normal or is something wrong with both of them ?. I have not done anything but fill both rifles.

Yes. The Icon will bump fire when the hammer spring adjustment is at its lightest (just before free flight or less), the tube pressure is at or below ~2000psi, and the rifle is decocked. A sharp strike on the ground will produce a full shot under these conditions. Not a burb, blip, etc... a full shot that is well capable of firing a pellet at high speed, should there be one in the barrel.

One solution would be to install a longer spring that adds preload. Not a great solution because hammer bounce is already an issue, and it might not even fix the issue. A stiffer hammer spring adjusted to near zero free flight should alleviate the issue at least some, not allowing the hammer to travel far enough back under it's own weight to produce a rebound.

[naptemp]

The weather was finally nice enough to take the ICON out and shoot today.  For some reason the trigger doesn't engage all the time.  About every 3rd or 4rth shot I'll cock the gun and nothing.  If I cock it a second time it will shoot but of course I need to remove the magazine when I do or I'll have a double feed.  Is anyone else having this problem?  Is there an easy fix or should I just send it back??

Part of the sear is extremely rough and is the cause for the "phantom cocking". It gets hung up in the reset cycle and the hammer gets locked in place but the sear isn't set all the way so it won't fire when the trigger is pulled. Once the area is filed and polished it cocks without fail. Obviously this is going to be a problem for the average consumer.

Can you post a photo of which part of the sear needs to be polished?

[NonGrata]

The weather was finally nice enough to take the ICON out and shoot today.  For some reason the trigger doesn't engage all the time.  About every 3rd or 4rth shot I'll cock the gun and nothing.  If I cock it a second time it will shoot but of course I need to remove the magazine when I do or I'll have a double feed.  Is anyone else having this problem?  Is there an easy fix or should I just send it back??

Part of the sear is extremely rough and is the cause for the "phantom cocking". It gets hung up in the reset cycle and the hammer gets locked in place but the sear isn't set all the way so it won't fire when the trigger is pulled. Once the area is filed and polished it cocks without fail. Obviously this is going to be a problem for the average consumer.

Can you post a photo of which part of the sear needs to be polished?

next time I have an icon apart I will, if I'm still here.

Take your stock off and watch the sear assembly at the contact points while you're cocking the gun. You'll probably see it.

[nervoustrigger]

I decided to give the barrel a little attention.  First up was to remove the front sight.  I was expecting it to put up a fight so I made a simple slide hammer with a scrap of wood.  Before warming up the sight to soften it, I gave it a couple of moderate strikes with the slide hammer and it popped right off.  Turns out it simply had a brittle adhesive holding it and a flat for indexing.


Starting at the leade, I used a generic Cratex point and wet/dry sandpaper to break the sharp step in the rifling.  Then I poured a cast lap and worked the bore.  There were two tight zones at approximately 25% and 75% of the way from the breech which took a bit of work to blend out.  Here's a pic of the lap after the job was done.


Then it was time to deal with the irregular factory crown


After cutting it back and recrowning:


Then cleaned the bore and reinstalled the barrel and pulled some patches with Johnson's wax.  Waited a bit for the solvent to evaporate from the wax, then grabbed the Norma 17.6gr domes to shoot some test groups.  It seems to have responded nicely.  The first 3 groups at 30 yards measured 0.22", 0.36", and 0.19".  Average of 0.257" or 0.82 MoA.

[K.O.]

nice job Jason...one of my favorite feelings is when the work pays off and a bargain turns into BARGAIN. ...

that kind of accuracy for a buck and a quarter... not bad at all...

the Bargain Gate $106 .177 I got finally made it back to Crosman yesterday... if it had just needed the barrel work would have kept it... but a gauge stuck at 1200psi and not holding air..

so a replacement or refurb of it should be on its way for me to evaluate soon...

I really like my 22 and do not regret getting it for a good bit more than this deal... in good conditions I feel anything above moa at 50yards with H&N and JTS 18g is not the rifles' fault...

looks like you could estimate twist using the rifling on the lap..

Have my other .177 set for the heavy stuff love that it keeps up with the Hatsan Hydra/Flash .177 FPE... and it really likes the Beast and Seneca Domed..

Will have to dig up the targets I shot at factory setting do not think many have been posted for the .177s... 

[Dextrose]

This ? is for Jason. What do you use and what process to achieve a nice concentric crown? I'd love to be able to do it @ home as well. Great job!

[K.O.]

not Jason... but this one looks to be done on a lathe because of the angle... looks like the muzzle was just barely rounded to finish... In Jason's write up you can see a good crown just done with a drill and brass screw...

https://www.gatewaytoairguns.org/GTA/index.php?topic=130555

[nervoustrigger]

nice job Jason...one of my favorite feelings is when the work pays off and a bargain turns into BARGAIN. ...

that kind of accuracy for a buck and a quarter... not bad at all...

Hi Kirby, yes sir I'm happy with how the .22 is turning out.   I am interested in how your replacement .177 does so I'll be keeping an eye out for your update.