Had to tear done the B26 again

[DMikeM]

Well my .177 Cal B28 was shooting wild and inconsistently after installing the crosman seal and spring, 2 washers on top of the spring one on the bottom. Couldn't get it to group tighter than 3/4" at 30 yards and many flyers. Also the kick was hard enough to knock the AO distance marks ring right off my Barska scope. I also thought the spring had broke as it started to twist and vibrate pretty bad.
I found that the Heave tar had totally broke down to a light grease and seeped up over to the top of the seal but the spring was fine and had no bends in it. Cleaned it all up again put some buttons on the piston replaced the zinc washers on top with one hardened washer, used less moly around the piston below the seal. Put a little more polish in the cocking slot and the shoe groove. It feels really good to shoot again and looks to be grouping like it used to 1/4" over lapping shots at 30 yards. Have to put a few more rounds through before I chrony it again. I used much less tar this time, I hope it stays put.

[Gene_SC]

A little moly goes a loooooooooooooong ways... Same with tar....

[Bogey]

We learn by doing.

[DMikeM]

Gene_SC - 5/16/2010  7:37 AM

A little moly goes a loooooooooooooong ways... Same with tar....

Yep sometimes tooooo loooooooooong!

[CharlieDaTuna]

Not sure how the heavy tar would breakdown, emulsify or thin itself out to a light grease and how you would get any tar in front of the seal if ithe spring was lubed properly. The viscosity may change if the gun gets hot out in the sun or something but will return for the most part to it original state when cooled down. That is why Pro-Tuners when they work on guns take into consideration what part of the country the gun is being used in when weighing what lubes and how much to use. Also, if tuned and lubed properly, there should be little or no heavy tar transfered to the action walls or even near the compression chamber. And if it kicked that hard, it sounds as though there was detonation.

[DMikeM]

Thanks for the reply CDT.

It was warm yesterday and I was shooting all day off and on, the gun was left outside but I covered the action with a towel when i walked away. It was much thinner than I would have thought just due to temps.
But it was shooting harsh from the start after the last spring change. I am thinking it was that extra washer (maybe). But it shoots pretty smooth now, maybe the buttons and extra polishing helped. Need to get out and shoot some more, been too busy today to play.

[shady816]

look forward to seeing some numbers mike... I finally got around to my b26 today after tearing it down I see why it was eating seals the inside walls of the tube have a gouge that goes from end to end looks as if they push the breech block in thru their at the factory and it is substantial gouge so I tried honing it out and was able to make it better but you can still see it but after reassembling the gun with the original spring and custom guides and proper lubes it was shooting jsb exact 8.64 at 850 fps which is around where I want it but was disappointed in what I found and there is no way removing the piston or installing could have made that mark so it looks like I will settle for what she is and will probably never be any better.

[DMikeM]

Your lucky with those numbers. Mine is around 750 with Beeman 7.2 gr hollowpoints. I ran some AA Falcon 4.52MM 7.33 grain pells through and got about 780, I tweaked the skirt with my homemade Pell tool and got 880 but they do not group well after the tweak. I really think Pyramyd sent me the 4.5s with the wrong sticker on them as they sink right in the barrel feed with no resistance at all. I will Chrony a few more pellets tomorrow if I get a chance.