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Discussion Starter · #1 · (Edited)
When my tsd sd700 vsr10 imitation (same gun as well mb03) is cocked, the bolt will not slide all the way forward. Instead, it will still have a couple milimeter to go, causing the cylinder head to not go far enough into the hopup bucking. The gun still shoots, but there is a major compression loss because of the air leak between cylinder head and bucking, and the bb's don't go nearly as far as normal.

Important info:
-When the trigger box is allowed to slide forward (screw removed) the bolt goes forward fine, even when cocked. This is because the trigger box moves forward a bit as the bolt goes forward, and the problem is solved. When the screw is back in place, and the trigger box is secure, the bolt problem persists. I cannot leave the screw out or the spring guide stopper will become loose, causing slam-fire.
-Bolt moves forward fine when gun is uncocked.
-I just got a new trigger box to fix the problem, but it did not help. Problem is unlikely to be with the trigger box itself.
-Everything looks aligned and working perfectly, which is why I'm completely stumped.
-Problem has nothing to do with outer barrel/hopup unit, as I am testing with only the bolt, trigger box, and reciever/bolt holder.
-Problem does not have to do with the piston O-ring or part #60 in the diagram below, because the problem has persisted when those objects were removed.
-Everything in the cylinder looks fine to me.

Diagram:
http://www.airsplat.com/Manuals/AR-HA-231-VSR10-13.jpg
Basic Bolt Operation:
http://www.google.com/imgres?start=...=166&tbnw=206&ndsp=12&ved=1t:429,r:1,s:91,i:7

Pics of the problem:
Bolt in correct forward position (uncocked):
img189.imageshack.us/img189/504/goodyy.jpg

Bolt cocked, cannot go fully into forward position:
img714.imageshack.us/img714/1724/badnc.jpg

I'm completely stumped, and simply cannot find anything wrong, even though the symptoms show the problem as obviously a problem with the relation of the trigger box to the bolt. Any help will be appreciated. Thanks.

Wow!!! My new cylinder kit (piston, spring guide, spring) just arrived and it did nothing to help my problem. I've got a new trigger box and a new cylinder kit, yet the bolt still doesn't go all the way forward when the gun is cocked! Therefore I can conclude that the problem is NOT caused by my slightly bent piston. The good news is that my new cylinder internals are made out of STEEL instead of some polycarbonate.

NEW EDIT: Major Breakthrough in progress! I found out that the bolt could only move forward all the way when the gun is uncocked BECAUSE THE SPRING GUIDE STOPPER COULD WIGGLE FORWARD. When the gun is cocked, the spring guide stopper is prevented from moving forward (because the piston sear catches the piston) and the bolt cannot go all the way forward. It's really just the last mm or so, but that makes a huge difference!
 

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Discussion Starter · #3 ·
Nope

Maybe there is a jam or something inbetween the bolt and where the bb goes
Nope, that is impossible because I am testing this with only the bolt, trigger box, and the bolt reciever. The entire outer barrel/hopup was not attached, and I'm not feeding any bb's while testing this problem. Thanks for the answer though!
 

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When you try to push the bolt assembly forward those remaining millimeters, what happens?

And do you have chronograph readings?
 

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Discussion Starter · #5 · (Edited)
The bolt assembly will not go forward those remaining millimeters, no matter how hard I push. However, if the trigger box is allowed to slide forward (by removal of a screw) the bolt will go forward fine because the trigger box is allowed to slide forward those few millimeters at the same time. I do not have a chronograph but I know for sure that the gun is losing power from this problem because:
-It's not the hopup's problem. I bought a brand new hopup, installed it correctly, no change. Hopup seems to be making bb's go up quite a bit, but they're just dropping due to a notable loss in power.
-I removed the screw holding the trigger box to the reciever to let the trigger box slide forward, allowing the trigger box to move forward and solving the bolt problem. The gun shot normal, as to say, very well, shooting the bb's ~250 ft as expected. However, this isn't a permanent fix because without the screw holding the trigger box secure, the spring guide stopper will occasionally become loose and cause the rifle to slam-fire.

I suspect my spring guide stopper, but it seems to fit fine... I just don't know what else could be blocking the bolt, as the operation of it seems simple enough:
http://i3.photobucket.com/albums/y85/Python890/boltoperation4.jpg

In case of broken link:
http://www.google.com/imgres?start=...=166&tbnw=206&ndsp=12&ved=1t:429,r:1,s:91,i:7

EDIT: I guess I could fix the problem by taping the spring guide stopper secure... However, in order for the trigger box to slide forward properly the trigger guard also needs to go, and I like my trigger guard.
 

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Do you have a weaker spring? If you do, try swapping it out and see if you can push the bolt assembly forward.

Your description of the situation points to the spring guide stopper as the culprit just as you said. Is your spring guide stopper the same one from your previous trigger unit?
 

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Discussion Starter · #7 ·
No, it's a different one. The spring guide stopper is brand new. Should it fit perfectly onto the spring guide, leaving no spaces in between? I've tried using various things as a replacement for the stopper (i.e Allen wrench) but the gun slam-fired. Unfortunately, I do not have a weaker spring. I'm using the stock spring that came with my gun.
 

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Discussion Starter · #8 · (Edited)
New update: I simulated cocking the gun without the spring (I just let the piston sear catch the piston to simulate the positioning of everthing in the cylinder without the spring) and the bolt slid forward fine. Now, what in the world could the spring be doing to block the bolt from moving forward all the way?
Update 2: I have found out that the piston is slightly bent. However, I am a bit doubtful is this is the cause of the problem, because the bending is only slightly noticeable, and the piston fits fine inside the cylinder.
 

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I've seen a similar problem with Aps2/Type96 guns.

What tends to happen is the spring guide stopper may be tilting backwards after it is cocked. When the bolt is pushed forward, the cylinder side closest to the bolt is pushing against the tilted spring guide stopper which prevents you from pushing it all the way.

Check to see how wobbly your spring guide is inside of your cylinder. It shouldn't tilt too much, if at all.

If you have bearings on your spring guide, try taking them off since you can't use a weaker spring.
Double-check that the spring guide stopper is installed properly.
If neither of those work, pull out the spring guide stopper little by little (but not too far) and cock the bolt assembly each time. There may be a point where the cylinder can be pushed in all the way. This isn't a permanent fix, but knowing the result can help you resolve your issue.

This also usually occurs when using a strong spring. I'm guessing you're using an m150 or stronger. What is your spring rating?
 

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Discussion Starter · #10 ·
Thank you very much, the spring guide stopper does seem like it wants to tilt backward when the gun is cocked. My spring is a stock tsd sd700 spring, rated at 430-450 fps w/.2 bb's, a vsr-10 cylinder, and a 509mm barrel. I guess that would be an m130? Also, what do you mean when asking if my spring guide wobbles? When the contents of the cylinder (spring, piston) are put into the cylinder, the spring guide doesn't seem to wobble. However, when the spring is taken out, the spring guide will wobble considerably. If you wanted to ask if the spring guide stopper wobbles, then yes, it does wobble/tilt quite a bit when it is stuck between the spring guide and the back of the cylinder. I do not have bearings on my spring guide.
 

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Much appreciated taking the time to answer my questions.

It seems like your spring guide stopper is somehow not fitted properly into your trigger box. To my knowledge of VSR-10 trigger boxes, the spring guide stopper should not tilt backwards at all. Perhaps someone else can confirm this as I do not have my vsr-10 rifle on me right now.
 

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Discussion Starter · #12 ·
Much appreciated taking the time to answer my problem.

Another guy from another forum theorized that my (slightly) bent piston is causing the piston sear to catch the piston in the wrong place/angle.

My spring guide stopper is tilting/wobbling quite a lot in my trigger box. I think I'll ask around if it's supposed to do that. Also, I can't pull the spring guide stopper out while the gun is cocked, seems the pressure of the spring is making it stuck, and pulling it out slightly before cocking has caused slam-firing. I'll let you know the results after I ask some vsr10 owners. Thanks!
 

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Discussion Starter · #13 ·
A vsr10 owner (Fuzzywolly) said:
"My spring guide does wobble, but its a laylax zero trig, and the spring guide stopper tends to do that. However, once it gets locked in place when attached to cylinder, it does not wiggle."

Hmm.... my spring guide stopper wiggles a bit even when it's locked in place then attached to the cylinder.
 

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Discussion Starter · #14 ·
Wow!!! My new cylinder kit (piston, spring guide, spring) just arrived and it did nothing to help my problem. I've got a new trigger box and a new cylinder kit, yet the bolt still doesn't go all the way forward when the gun is cocked! Therefore I can conclude that the problem is NOT caused by my slightly bent piston. The good news is that my new cylinder internals are made out of STEEL instead of some polycarbonate, and cylinder compression is very damn near perfect.
 

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Wow!!! My new cylinder kit (piston, spring guide, spring) just arrived and it did nothing to help my problem. I've got a new trigger box and a new cylinder kit, yet the bolt still doesn't go all the way forward when the gun is cocked! Therefore I can conclude that the problem is NOT caused by my slightly bent piston. The good news is that my new cylinder internals are made out of STEEL instead of some polycarbonate, and cylinder compression is very damn near perfect.
So just to make sure, you got a new cylinder kit and a newer trigger box?

Which cylinder kit btw?
 

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Discussion Starter · #16 · (Edited)
Link for cylinder kit:
http://www.pyramydair.com/s/a/Well_MB03_07_Series_Sniper_Rifle_Power_Up_Kit/3087
Although it says "Well MB03", it also fits the SD700. The two guns are identical.
Obviously not your PDI stuff, but it's still a million times better than my stock cylinder internals. And yes, I'm currently using both my new cylinder set and my new trigger box. I'm baffled by the fact that the problem is not yet solved. I could only imagine that 1.) the problem has to with the reciever/bolt holder itself (seems unlikely) or that 2.) has to do with the outer shell of the bolt (also seems inplausible). I know this because I've simply replaced everything else!
EDIT 1: I have an issue with the new, more powerful spring I just bought as part of the cylinder kit. The spring is very hard to get inside the cylinder, and when I finally got it in, I couldn't manage to cock it. Not because I'm weak, but rather because it just seems IMPOSSIBLE to cock. It also make a strange grating sound when I try to cock it, perhaps because the spring is scraping against the wall of the new piston.

NEW EDIT: Major Breakthrough in progress! I found out that the bolt could only move forward all the way when the gun is uncocked BECAUSE THE SPRING GUIDE STOPPER COULD WIGGLE FORWARD. When the gun is cocked, the spring guide stopper is prevented from moving forward (because the piston sear catches the piston) and the bolt cannot go all the way forward. It's really just the last mm or so, but that makes a huge difference!
 

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I have an issue with the new, more powerful spring I just bought as part of the cylinder kit. The spring is very hard to get inside the cylinder, and when I finally got it in, I couldn't manage to cock it. Not because I'm weak, but rather because it just seems IMPOSSIBLE to cock. It also make a strange grating sound when I try to cock it, perhaps because the spring is scraping against the wall of the new piston.
So you've never been able to prime it with that spring inside the cylinder?

That grating sound is the sound of the piston and spring rubbing inside the cylinder. The spring in the kit is a thin, but powerful spring so the piston and spring tend to bend side to side in the cylinder.

Major Breakthrough in progress! I found out that the bolt could only move forward all the way when the gun is uncocked BECAUSE THE SPRING GUIDE STOPPER COULD WIGGLE FORWARD. When the gun is cocked, the spring guide stopper is prevented from moving forward (because the piston sear catches the piston) and the bolt cannot go all the way forward. It's really just the last mm or so, but that makes a huge difference!
Assuming the trigger box and spring guide stopper is installed properly, I would have to agree with you that it's either the receiver or the bolt.
 

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Discussion Starter · #18 · (Edited)
It seems like the problem is that the bolt and the reciever do NOT align properly, forcing the spring guide stopper to shift. Problem may be solved with some filing/sanding. I'll upload a pic soon. I haven't been able to rack the bolt (or "cock" or "prime" it) with the new powerful one. It's quite a bit longer than my stock spring, and it's a challenge just to get it inside the cylinder and screw the cylinder head on. I'm definitely not among the strongest, but I'm not the weakest either. It seems at least 10x harder to rack than the stock spring! The new spring is rated at 550 fps I believe, and it will probably kill my sears if I used it.

PIC: http://img19.imageshack.us/img19/4936/dsc0192od.jpg

As you can see, the place where the spring guide stopper is supposed to fit in is not aligned properly between the cylinder/bolt and the receiver.
 
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