Bolt-stick problems Any help appareciated

[kiltedpainter]

I've got an old 68 Classic that i am using and i am having some bolt stick issues. I'm not sure what the problem is but i'll give more details after this quick parts list.

Parts list for marker:
12" J&J 2 piece barrel, glued
Red rail,
Sawed off trigger frame,
Aftermarket double trigger (forced in place it seems)
Standard valve,
Standard powertube/on-off, (matching serial numbers on the powertub and valve)
ANS Phase 2 bolt,
.220 powertube spacer.
Standard yellow-ish colored spring
Regular bumper
Sear pin length - 1 inch from where the end of the sear mechanism is screwed on to the sear rod.


What happens is I will have the marker on HPA and get off a string of may 6-7 shots then the bolt will stick. At that point I'll reach in and push the bolt back in place. Shooting again i get about the same number of shots per string. I'm not sure if it's the after market bolt, or if the spring is too old, or even if it's something else entirely. Any help would be greatly appreciated.

Also, I picked this marker up in about November and have yet to get it working fully without either cycling problems or bolt stick issues.


Hope i've given enough information for a good diagnosis.

-Kiltedpainter

[Spider-TW]

1) Lots o' Lube?

2) Check the breech of the barrel and bolt exterior for unusual wear. Old barrel orings on the twist lock barrels can give you alignment problems. I have read of one bent body before (they thought), but I would expect the frame to break first on a classic.

3) I've never seen a bent bolt piston, but I expect you could drop one just right and do it. Roll the bolt and make sure the piston (center) is straight.

Hopefully it is just your barrel hanging it up. I tried a J&J once; the oring grooves were not cut deeper for the ball detent (nubbin). This made the orings push out more on that side and it wouldn't fit in the body. I just sent it back. I figured it was just a manf. defect, but it was the last one in stock.

[__Phoenix__]

Try using an original AGD level 7 bolt.

[kiltedpainter]

I may try the barrel without the O-rings to see if it works but it will be a while before i can test it with the level 7 bolt.

Spider-TW, what do you mean by rolling the bolt? I've never heard of that.

[Spider-TW]

Just roll it on the table or in your fingers and see that the center of the bolt that fits in the power tube doesn't appear to wobble. Like rolling a pool cue on a pool table. The center piston of the bolt should appear to stay in the middle of the bolt without a wobble. That way you know no one skipped it off the concrete and bent it.

[Spider-TW]

That reminds me, someone here mentioned that the bolt actually rotates a little on each shot, at least when you have bad sear engagement (or bad dis-engagement). That is why you can get wear all around the bolt lip instead of just one place. I would think that with a little warp in the bolt piston and a little mis-alignment in the barrel, you would rotate the bolt a little every shot and wind up binding more on some shots than others.

[kiltedpainter]

I think i neglected to mention a couple of possible key bits of information. The bolt only sticks with about a quarter of an inch visible looking down into the powerfeed.
On other thing happens every time as well. The On-Off doesn't move back into position until i force the bolt back down into place. once the sear locks in it, the On-Off responds and moves to hold the sear-pin forward. At that point, it will fire again.


Also, on some occaisions, i pull and there's this sound of a sort of pressure bleed off down the barrel. if there was a word for the noise i'm getting it'd be something like this: Pshew. quick sort of burst then a loud hissing. This will occaisionally happen as well.



on the subject of bolt wear and rotation, there is noticable wear on one side of the bolt more than the other as well as noticeable wear on one side of the powertube tip as well. They don't exactly correspond but it is noticable.

[Spider-TW]

I forgot that people tinker with their sear adjustments and on-off pins. Sounds like the sear is dragging, if you are talking about bolt wear at the sear engagement. Or is the wear on the body/maintube of the bolt?

Make sure that when the marker is aired up, there is a small gap between back of the trigger and the adjustable push rod on the sear. I think it is about 0.5mm to 1mm, but the exact dimension is on one of the stickies upstairs (on this forum). It mainly needs some slack.

Make sure your sear hasn't been altered (filed) anywhere to shorten up the clearance. New ones are cheap. Get a power tube tip while you're at it if yours is worn(!).

If all that looks ok, check the length of the on-off pin. I'm not sure, but an RTPro pin is 0.765" instead of the 68Automags 0.750", and that might push the bolt end of the sear up enough to catch (if someone installed an RTPro pin).

I've never had a bolt for more than about 24,000 rounds just because I was changing designs, but I have never had a worn bolt lip. Point being that they don't normally wear a lot.

[slasherdan]

I had a similar problem with my E-TAC and someone once told me that it's a shim issue. I was told that I most likely need to add a shim or two. Seeing how I lacked any experience with the MAG I walked down the street and dropped it off at AGD ... they took care of it for me.

[athomas]

That is a classic symptom of level 7 bolt stick due to a worn bolt spring. Replace the bolt spring as a first attempt to repair.

[Spider-TW]

That is a classic symptom of level 7 bolt stick due to a worn bolt spring. Replace the bolt spring as a first attempt to repair.

How many rounds does it take to get to that point (with and without lube)?

[athomas]

A year or two in the gun without firing a round could result in the compressed spring being weaker. From my personal experience, the firing operation usually takes about 30000 shots before a new spring starts to exhibit noticeable bolt stick. Lubrication does not affect the ability of the bolt spring to last longer. You actually shouldn't put any lubrication on the bolt spring. It can transfer to the bolt and then to the balls and barrel which will affect your accuracy.

[Spider-TW]

Hmm, I can't figure the storage problem since the spring isn't compressed that much. Also, I would submit my own, statistically significant (because it's mine), level 7 setup that spent almost 13 years in an attic and worked for a full day until the orings started to fall apart. A new seal kit fixed it up (my spare kit was crumbling too). That's why I still shoot mags. No spring problem there, though. It only had about 14000 rounds through it as a lvl 7 before I changed out to the Xvalve and lvl 10.

[athomas]

The bolt spring is slightly compressed just by putting the valve in the gun. It doesn't affect it a great deal but does eventually reduce its overall life. Also, don't forget to count the dry firing.

I remember years ago, the tournament players used to change the bolt springs before every tournament. It was a known problem. You could buy a basic tune-up kit which consisted of a bolt spring and some basic orings rather than purchase a full kit.

[Spider-TW]

I do remember the spring kits. I still have three regular springs for one gun, on top of my xvalve assortment. I remember the spring changing for tournaments. I guess I have never been able to wear a spring out for one reason or another. I have to admit that I lube the bolt lip and sear and wipe lube the bolt/spring surface. I will definitely try it dry to see if my accuracy improves. My paint has been a little lumpy lately though.

P.S. So what happened, kiltedpainter?