Gap between breech and tube on new DiscoveryApril 3 2013 at 7:23 PM
|ScottB (Login ScottB75)|
I just received a replacement Discovery from Crosman, the previous one had serious POI problems. Crosman just sent me a new one. While going over it I noticed a gap between the breech and the tube. I haven't had a chance to shoot it yet, if it shoots fine should I just leave it be? Or could the gap cause problems down the road? The gap is pretty big, from the front of the breech all the way back to the transfer port is a gap. What do you think? I am thinking, send it back and get another one.
|This message has been edited by ScottB75 on Apr 3, 2013 7:27 PM|
The breech screw is likely loose or more likely missing
|April 3 2013, 9:31 PM |
don't shoot it! you'll just have a massive air leak.
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The raised breech front
|April 3 2013, 9:57 PM |
is the usual, not the exception. Don't go crazy on the breech screw, use a clamp to compress the breech to the tube, then GENTLY tighten the 4/48 screw. I doubt it will do any good. If you do a search you will see the best fix is to add a second barrel band right in front of the breech to hold it down and stabilize it.
Plus on on the bar clamp solution
|April 3 2013, 11:45 PM |
Use that to force the breech to a nice tight fit then just simply snug up that little breech screw. No need to put a whole bunch of torque on that screw. Once that bar clamp is released that screw will be plenty tight.
If you can not compress it tight with a bar clamp then there is something wrong with the port.
Re: Plus on on the bar clamp solution
|April 4 2013, 11:12 AM |
It looks like the transfer port is too long (common problem) with the Discoverys. I just carefully stoned my TP a little shorter,and it fit well. It also stopped the POI shift problems. Be sure to use a clamp on the breech,and don't over tighten the screw.
That might be a factor with my Discovery/Katana..(see post below)
|April 4 2013, 3:57 PM |
Would you describe the process- do you stone the tapered top or the flat bottom of the transfer port?
Extra Band in front of breech is the way to go.
|April 4 2013, 2:50 PM |
That's what I ended up doing and it works really well.
I tightened the screw.
|April 4 2013, 7:18 PM |
I clamped down the breech and tightened the breech screw. The gap is still there. We'll see how it does when I get a chance to shoot it. Probably this weekend. If the accuracy is good I'll probably leave it be, if it isn't, I'll look and see if the transfer port seal is a little too long.
How many of you have this same problem with your Discovery?
It is a common issue
|April 9 2013, 11:34 PM |
I sanded the rubber seal instead of changing the metal TP. It was easier to do and easier to replace should it be needed. Fixed the issue on my Discovery that had the exact same issue.
POI shift ended with that mod.
one way to find if your TP is too long
|April 4 2013, 8:17 PM |
remove it and tighten down the breech. if it closes the gap than the TP is too long. if it doesnt, than thats the way it is and nothing you can do about it. not a defect, just the way it fits. now trying to remove some of the TOP of the metal TP might cause it to leak if just the right amount is not removed. Not sure if its worth trying to remove any.
now if removing the TP closes the gap than dont use the metal/stock TP. find some 1/4" ice maker tube, ( ya need some email me your address , I'll send ya a piece) cut it the length of the oem TP , install and tighten down the breech. if you find out it doesnt tighten down enough its easier to remove some of the plastic than the metal oem TP. Now you should gain some fps from the larger size of the ice tube. I have replaced all my stock TP with the ice maker tube, all but my Prod.
Now as far as using a clamp to tighten the breech screw, I never have used one with the ice tube. I dont have super human strength but you should be able to squeeze it closed enough to tighten it down, the clamp is used by some cause they think they need to tighten it down tighter than tight LOL.
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one step closer to the ultimate goal
I removed the transfer port.
|April 4 2013, 10:44 PM |
When I removed the transfer port and attached the breech,the breech fit on top of the tube tight without any gap. I do believe that the transfer port is just a bit too long. I might just try the 1/4" tubing.
|This message has been edited by ScottB75 on Apr 4, 2013 10:56 PM|
the plastic tube is more forgiveing
|April 4 2013, 10:56 PM |
it can be a tad too long and it will compress some to make a good seal. too long and it will compress too much and may cause a restriction. cutting to fit just right may take a couple times but it makes a better seal, with out having the stock rubber Oring, the 1/4 tube fits directly on the valve . when you do the tube, look at the barrel side, dry fit in the hole, you may have to square the hole or round the tube . but with the tube , it does make a better fit.
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one step closer to the ultimate goal
Check the TP hole in barrel
|April 19 2013, 8:28 AM |
I bought a new Crosman 1377 that had the same gap problem, the TP hole in the barrel had not been countersunk for the TP to fit in.