Slide does not lock back on last shot

M4 · August 5th, 2009, 11:51

it still doesnt lock back when i dryfire. thanks for the suggestions so far.

surebet · August 5th, 2009, 11:54

Are you using duster or propane?

M4 · August 5th, 2009, 11:56

Quote:

Originally Posted by surebet

Are you using duster or propane?

Ive been using propane

surebet · August 5th, 2009, 12:24

Never mind then, I though it was a pressure issue.

m102404 · August 5th, 2009, 13:03

Some of this has probably been said already, but it might be worth trying it all from scratch again if you're at a loss. It might not be the best way to do it...but it's what I'd do if I was troubleshooting.

(Note...turn your hopup on about half way...see if that helps with the bb rolling out thing. It might also help with building up pressure so the blowback works a bit better).

*** Check to make sure there's no bb in the chamber and that you're pointing it in a safe direction ***

1. Insert an empty mag (gas or not, doesn't matter), rack the slide back by hand and let go. If it locks back, you know the feed/empty tab of the mag is good and hitting the right part of the slide catch....go to #2
- if it doesn't, either the bb follower is worn, the slide catch is not getting tripped by it, or the notch of the slide is not catching...inspect, replace as necessary, retest
- if the slide feels rough or "sticky" you need to investigate further as to what is hanging it up...go to #3

2. If the slide locks back manually as in #1...gas the mag up fully (min 5-7sec...longer isn't really going to hurt anything...a Hicapa mag takes 10sec or so). Be sure to use a full propane/duster tank...mostly empty tanks will not always fill properly. Put a drop or two of oil right on the fill valve of the mag so it gets blown in by the gas. WAIT for the mag to reach room temp...better yet get it to reach body temp by putting it in your pocket. Small Glock mags don't hold a lot of gas and are very sensitive to colder temps.
- insert the "warm" fully gassed mag (no bbs)...rack the slide manually. Hold the pistol straight out from you (level...no sideways/tilted gangster stuff) and fire one shot. If it locks back...retest with one bb (use 0.20g or heavier bbs)at a time, racking manually each time...do not fire faster than 1 shot every 5 seconds (not practical...but we're testing here). If it works...you're good to go and it's probably that your mags are cold or don't really hold enough gas. Guns that recoil hard and vent use a lot of gas and don't have "enough in the tank" to get the pistol functioning at the end of the mag...cold mags compound the problem.
- if that's good, retest as above with more than one BB (i.e. 3). It should feed/feed/feed/lock. If that works try shooting them quicker...regas and warm your mag if it feels cold to the touch (most do cool down quite a bit). If that works...then your pistol with that mag is good. Retest other mags the same way.

3. If it's not locking back after a shot with a bb or if it feels sticky/rough when you rack it back manually...
- there could be a fitment issue with the nozzle (on most pistols this is the cylinder of the blowback as well as the feeding nozzle) and the piston head. Some are rubber cups, others are o-rings, etc.... Some fit too tight and will retard the blowback by creating friction between the piston head and the nozzle body....this slows down the slide (maybe not enough to feed the next shot...pistols don't actually need to cycle very far to feed...but enough so that the slide isn't going back fully). Adjust the piston head to nozzle fit as necessary.
- the blowback unit (the housing that holds the piston/nozzle/etc) could be rubbing excessively on the frame. Most often this is easiest to tell by taking out the barrel/recoil guide spring assembly and manually moving the slide. If it's rubbing/"grinding" you've got to smooth things out. There should be some bumps/clicks and the slide goes back...but it should be easy and smooth.
- the barrel/slide lockup might be binding in recoil...again smooth enough to feed, but not enough to let the slide do it's thing. These are tough.
- the recoil spring/guide might be binding...sometimes the coils of the springs get messed up and cross over each other or jam up. Best off to replace. Although the shot to shot times increase...you can use a "weak" stock spring to see if the slide cycles properly. Depending on the pistol some really stiff springs might cause it to not travel all the way back (in fact some are meant to short stroke a pistol).
- the rocket/float valve might be sticking/stuck/unbalanced. This valve and its spring control how much gas goes down the barrel and how/when it's shunted to start the recoil cycle. If you have a really light valve and a really stiff spring...it might not cycle fully. If you have a heavy valve and a light spring...it might not produce all the power that you'd want it to. Trial and error.
- if that doesn't work....go to #4

4. Junk it. Some are just gremlin guns...

There's probably a bunch of other stuff...
- sticky knockers, hammer springs, bad main seals, etc....

M4 · August 6th, 2009, 02:10

thanks alot everyone so far, ill start testing all of your theories

Duckman · August 6th, 2009, 04:35

it might also be something so simple as the spring in the mag isnt strong enough to apply enough pressure through the follower to overcome the little spring loaded friction nib at the end of the slide lock. test this with another mag. if you dont have another mag than take the mag you do have apart and give the spring a bit of a stretch. i have a 1911 classic...some mags will lock when empty but others wont.

tyson knows his stuff but this particular test takes a matter of seconds before you get into the other stuff.

so load the empty mag. rack it (it should lock), slap the bottom of the loaded gun to see if the little jolt will help the mag spring and free up the slide lock.

with the mag out, hold the slide all the way back and see if the slide lock has too much friction to move up and down. the little nib is supposed to be there but it shouldnt be rough or bind. it's also the same nib that gives teh little clicky feeling on the safety.

m102404 · August 6th, 2009, 08:33

Good catch Duck...

...basically every spring, screw, nub and touching surface can cause problems...even if they look right.

On hicapa's it's not uncommon for guys to crank on their left grip screw. Too tight and it can bind the plungers/spring that affect both the thumb safety and slide catch operation.

There's a ton of things that can be goofy in a GBB...start with the simple stuff.

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August 5th, 2009, 11:54	#17
surebet Vicious MSPaint Wizard Trader rating Join Date: Aug 2004 Location: Longueuil, Quebec	Are you using duster or propane? __________________ Annoyingly good with numbers Stop American Censorship

August 5th, 2009, 12:24	#19
surebet Vicious MSPaint Wizard Trader rating Join Date: Aug 2004 Location: Longueuil, Quebec	Never mind then, I though it was a pressure issue. __________________ Annoyingly good with numbers Stop American Censorship

August 6th, 2009, 04:35	#22
Duckman Trader rating Join Date: Dec 2002 Location: toronto	it might also be something so simple as the spring in the mag isnt strong enough to apply enough pressure through the follower to overcome the little spring loaded friction nib at the end of the slide lock. test this with another mag. if you dont have another mag than take the mag you do have apart and give the spring a bit of a stretch. i have a 1911 classic...some mags will lock when empty but others wont. tyson knows his stuff but this particular test takes a matter of seconds before you get into the other stuff. so load the empty mag. rack it (it should lock), slap the bottom of the loaded gun to see if the little jolt will help the mag spring and free up the slide lock. with the mag out, hold the slide all the way back and see if the slide lock has too much friction to move up and down. the little nib is supposed to be there but it shouldnt be rough or bind. it's also the same nib that gives teh little clicky feeling on the safety. __________________

August 5th, 2009, 11:51	#16
M4 Trader rating Join Date: Jul 2009	it still doesnt lock back when i dryfire. thanks for the suggestions so far.

August 5th, 2009, 13:03	#20
m102404 Tys Trader rating Join Date: Apr 2006 Location: Toronto	Some of this has probably been said already, but it might be worth trying it all from scratch again if you're at a loss. It might not be the best way to do it...but it's what I'd do if I was troubleshooting. (Note...turn your hopup on about half way...see if that helps with the bb rolling out thing. It might also help with building up pressure so the blowback works a bit better). * Check to make sure there's no bb in the chamber and that you're pointing it in a safe direction * 1. Insert an empty mag (gas or not, doesn't matter), rack the slide back by hand and let go. If it locks back, you know the feed/empty tab of the mag is good and hitting the right part of the slide catch....go to #2 - if it doesn't, either the bb follower is worn, the slide catch is not getting tripped by it, or the notch of the slide is not catching...inspect, replace as necessary, retest - if the slide feels rough or "sticky" you need to investigate further as to what is hanging it up...go to #3 2. If the slide locks back manually as in #1...gas the mag up fully (min 5-7sec...longer isn't really going to hurt anything...a Hicapa mag takes 10sec or so). Be sure to use a full propane/duster tank...mostly empty tanks will not always fill properly. Put a drop or two of oil right on the fill valve of the mag so it gets blown in by the gas. WAIT for the mag to reach room temp...better yet get it to reach body temp by putting it in your pocket. Small Glock mags don't hold a lot of gas and are very sensitive to colder temps. - insert the "warm" fully gassed mag (no bbs)...rack the slide manually. Hold the pistol straight out from you (level...no sideways/tilted gangster stuff) and fire one shot. If it locks back...retest with one bb (use 0.20g or heavier bbs)at a time, racking manually each time...do not fire faster than 1 shot every 5 seconds (not practical...but we're testing here). If it works...you're good to go and it's probably that your mags are cold or don't really hold enough gas. Guns that recoil hard and vent use a lot of gas and don't have "enough in the tank" to get the pistol functioning at the end of the mag...cold mags compound the problem. - if that's good, retest as above with more than one BB (i.e. 3). It should feed/feed/feed/lock. If that works try shooting them quicker...regas and warm your mag if it feels cold to the touch (most do cool down quite a bit). If that works...then your pistol with that mag is good. Retest other mags the same way. 3. If it's not locking back after a shot with a bb or if it feels sticky/rough when you rack it back manually... - there could be a fitment issue with the nozzle (on most pistols this is the cylinder of the blowback as well as the feeding nozzle) and the piston head. Some are rubber cups, others are o-rings, etc.... Some fit too tight and will retard the blowback by creating friction between the piston head and the nozzle body....this slows down the slide (maybe not enough to feed the next shot...pistols don't actually need to cycle very far to feed...but enough so that the slide isn't going back fully). Adjust the piston head to nozzle fit as necessary. - the blowback unit (the housing that holds the piston/nozzle/etc) could be rubbing excessively on the frame. Most often this is easiest to tell by taking out the barrel/recoil guide spring assembly and manually moving the slide. If it's rubbing/"grinding" you've got to smooth things out. There should be some bumps/clicks and the slide goes back...but it should be easy and smooth. - the barrel/slide lockup might be binding in recoil...again smooth enough to feed, but not enough to let the slide do it's thing. These are tough. - the recoil spring/guide might be binding...sometimes the coils of the springs get messed up and cross over each other or jam up. Best off to replace. Although the shot to shot times increase...you can use a "weak" stock spring to see if the slide cycles properly. Depending on the pistol some really stiff springs might cause it to not travel all the way back (in fact some are meant to short stroke a pistol). - the rocket/float valve might be sticking/stuck/unbalanced. This valve and its spring control how much gas goes down the barrel and how/when it's shunted to start the recoil cycle. If you have a really light valve and a really stiff spring...it might not cycle fully. If you have a heavy valve and a light spring...it might not produce all the power that you'd want it to. Trial and error. - if that doesn't work....go to #4 4. Junk it. Some are just gremlin guns... There's probably a bunch of other stuff... - sticky knockers, hammer springs, bad main seals, etc....

August 6th, 2009, 02:10	#21
M4 Trader rating Join Date: Jul 2009	thanks alot everyone so far, ill start testing all of your theories

August 6th, 2009, 08:33	#23
m102404 Tys Trader rating Join Date: Apr 2006 Location: Toronto	Good catch Duck... ...basically every spring, screw, nub and touching surface can cause problems...even if they look right. On hicapa's it's not uncommon for guys to crank on their left grip screw. Too tight and it can bind the plungers/spring that affect both the thumb safety and slide catch operation. There's a ton of things that can be goofy in a GBB...start with the simple stuff.

Slide does not lock back on last shot

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