GTA
General Discussion To Gateway To Airguns => China Gate => : cnsjones August 21, 2009, 08:20:39 AM
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Spent about an hour this afternoon with the MM B26-2 (.22 Cal.). Estimated pellets shot now at about 200-250.
Rifle continues to smooth out, although after fifteen shots today, the breech bolt AGAIN startedslightly loosening (even though I used a dab of Loctite on the threads last night.
Question: Is this a common issue with the BAM B-26 or do I need to do something different? The "Acorn" nut on the other side has a small lock washer under it. I wonder if it is not doing the job somehow, or if it could be the cause??
Conclusions from pellet test: (23 yards, Bag/back of hand--
1.Best Group: RWS Super Hollow Point 14.2 gr. (slightly smaller than Dime size group).
2. Next was about a tie between Gamo Hunter and RWS Hobby 11.9 gr.
The Hobby pellets "spread a bit more (nickle size),
3. Hunter pellet group was tighter -- just in a vertical line. This is when I
noticed the breech bolt loosening, so the Hunters just might be the best of all??? See pic, (if I can get it uploaded!)
These Gamo hunter also were the tightes in the breech. Even had one that did not want to go in, and I discarded it.
4. My particular gun does NOT like JSB Excact Jumbo Express. Spread out 1 i/4 inch group. This is the same result for these pellets
as right after I received the rifle. No noticeable improvements The other groups are somewhat tighter.
Comments appreiated about the breech bolt.
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I contacted Mike about the breech bolt coming loose on my gun too. He said to use blue lock tight or finger nail polish. I used the blue lock tight on the acorn nut but have only shot it about 20 times since and it seemed to stay tight but i will keep an eye on it. Maybe a better lock washer would help, there has to be an answer for this because there are a lot of happy B26 owners out there. I'm sure some of the happy owners will come through for us. My .22 seems to group the best with CPHPs so far but I'm still in the break in and testing mode. Thanks for the post on your pellet test.
Charlie,
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Interesting. I've never experienced this with my 28's,...but let me throw out an idea here. Has anyone removed the bolt and inspected the pivot surface of it? There may be a slight burr or roughness that may have developed during your break in period. Something like that could possibly loosen the bolt over time just by catching the breech block enough to slowly rotate it some,..like I said,...just an idea. You might polish this area some,...add a touch of moly to it, and follow the loc-tite instructions per Mike. But then again,..it may be a poorly made/shallow threaded component sub contracted out for the factory to use? This is why I replace all the factory screws/bolts in my rifles and scopes with higher quality components. And nothing's ever moved at all,... loc-tite never needed. Hope Mike chimes in on this issue. tjk
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The blue locktite fixed mine. After 100 - 150 shots it is still tight. The challenge is getting ALL of the lube off the threads while leaving it on everything else.
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Good point Gary. No arguement on that at all. tjk
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I started out doing that then got complaints so I quit......it's a strange problem, I haven't put loc-tite on any of my 26's and don't have any screws coming loose..well the one behind the trigger group needs attention every 100 shots or so but I like to keep it just snug so it doesn't hang up the safety...
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It seems to be a tolerance issue guys, and possible a lack of lube on the bushing and or thrust washers.
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Shouldn't be that Gene, I slap jm moly grease on them when I put them back together, could I be puttting to much?????
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Curious. Have never had a problem with the three I have owned. I wonder if the lubricant is the issue -- not on the washers, but getting into the threads of the acorn nut that locks the breech bolt. The Blue LockTite won't work well unless the threads are clean and free of any oil or grease. Might try some acetone on a Q-Tip to clean the threaded end of the bolt and making sure the nut is completely cleaned with acetone before the next application of LockTite.
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Just out of curiousity, I checked the bolt on my 28 last night. Gave the bolt just a hair more torque, restocked it, and barrel lock up was alot stiffer,...ended up loosenning the pivot back and should have left it the hell alone. How's that old adage go,.."if it ain't broke, don't fix it"!!!!LOL's tjk
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OK Mike and Gene, thanks for weighing in. I am a rank novice at disassembly of these guns. I can remove the stock, install scopes, but I know nothing about the procedure to go further. So with that said,-- I removed the acorn nut, and there IS lube both under/on the small lock washer and on the threads of the acorn nut (as determined by Q-tip)-- therefore on the end of the bolt threads as well. So the "dab of loctite a day ago did no good.
Next I started backing out the bolt to see how it felt turning. COULD THE BOLT BE SLIGHTLY BENT? There is a "tight spot" once per turn! Or maybe as tjk said a burr? or maybe on the breech holes?
So I want to find out! How do I safely remove the bolt from the breech/barrel? Step by step please.
I am pretty good with tools, have what I need (except airgun specific item like spring compressor - I see one in my future). Thanks.
Fuller
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When I used blue lock tight on my breech bolt acorn nut, I used alcohol to remove the greese from the bolt, washer and nut. It seems to holding tight so far after 100 shots. The gun is still new and the stock screws have to be check from time to time. If I do my part it will put 10 CPHPs into a dime sized group at 15 yards and this is great with my old shakey hands. I just want to say this is one great site and I have learned more from you guys than I could ever have imagined. Thanks to everyone.
Charlie,
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Charlie,PM sent.
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locktite will not hold if there is any grease on the threads. I lock tited both my B25 and B26 and now have no problem. Note: all screws would loosen due to recoil before the loctite.
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There is an "oil tolerant" version, but I'd imagine the bolt would have to be pretty clean first. Check out Loctite 243.
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Have not found 243 around here yet. Only Permatex version of 242 at auto parts store. Ace and HD don't have it and don't seem to know what "Threadlocker" Loctite is.
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Fuller, look in the paint section of the Home Depots' and Lowe's HI stores. They usually have a Loc-tite/Permatex display in that general vicinity!!!! I know that's where my local HD has it. tjk
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Yep they have LOT of "Loc-Tite" products!!! NONE of which include any variety of Threadlocker 242, 243, or any other variants.
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Actually the company I work for has the 243
http://www.heliproz.com/prodinfo.asp?number=181705
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As I said, new to Airgun disassembly. I want to remove the Hinge bolt to inspect it on the B26-2. It "binds" once per turn as you loosen or tighten it. So I want to find out why!
How do I safely remove the bolt from the breech/barrel?
Should I cock the gun before removing the hinge bolt or is that necessary? Thanks
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I bought some more pellets this weekend. Daisy "max precision", what a waste of lead! Worst one of the bunch by far. The Gamo "match" were the best, followed by the RWS superdomes and the Gamo "hunter's". I really wanted the super domes to be the best considering the price, but the Gamo match were the best at 20 yards.
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Did your Hunters fit tighter in the breech than the others?
I just tried to clean off the screw threads on the hinge bolt and the nut as best I could and put loctite in the acorn nut and retightened. I did not want to take the bolt all the way out without understanding the correct procedure. I think I could have cocked the gun to releive the pressure and tried to quickly pull the bolt out and inspect it, but decided not to do that yet. Will shoot another 50 times or so and see how it goes with the nut..
Just use the Daisy pellets for fast plinking to help season the barrel. I have some in .177 that I am using for the same in my Whisper. They really are lousy pellets.
I have more Gamo Hunters than anything else in .22, so will stick with them for a while and work with the B26-2. As of now it needs more "breaking in."
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Both of the Gamo pellets were tighter than the RWS super domes. Now I don't remember which one was tighter...lol. I wasn't trying to be scientific (perhaps I should have) but just having fun trying to see which ones my gun liked best.
The Daisy's were so bad, I was MISSING an aluminum can at 20 yards from a prone shooting position! They're terrible for anything more than 10 feet or so..LOL!