Happy_Bummed

This area is dedicated to the .25 caliber Benjamin Marauder by Crosman.

Happy_Bummed

Postby Ramatam » Fri Apr 27, 2012 7:55 am

So recently the .25 had to go back to Crosman. Stripped the Breech screws and couldn't remove the unit to add an HDD. It came back and they had totally replaced the action. Happy cause the old action could never get very good velocity ...even with a #10 spring. And the new one is showing promise in that department.
The other day I shot a target at 50 yards and to my surprise, it was like shooting a shotgun. No grouping at all. I cleaned the barrel real good with Goo Gone and dried it. The patches came out black at first and I thought, didn't I clean this barrel not too long before I sent it to Crosman? Cleaning improved things dramatically but things are different. Benji domes used to beat out JSB EK's in this gun, now it's the other way around. Then it dawned on me. Even though I told Crosman I was happy with the accuracy ....they replace the barrel as well. GROAN! Bummed. That old barrel was tight out to 100 yards.
So, the only thing to do is tear it down and lap the barrel this weekend. This stuff happens...hoping that lapping will improve things a lot. Not sure whether or not to call Crosman and see if they still have the old barrel. Got a feeling that it's long gone.
Ramatam
 
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Re: Happy_Bummed

Postby duga » Fri Apr 27, 2012 11:30 am

That sucks.

Don't know what you got til it's gone by Cinderella is going through my head right now
.25 Mrod, HDD, depinged, tuned at 880 fps with jsb exacts (20 shots 26 fps ES)
6-24x44 BSA Tactical side AO with 10 yard increments marked on elevation turret cause I like to click
bipod and sling

Lots of firearms that collect dust
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Re: Happy_Bummed

Postby Ramatam » Fri Apr 27, 2012 1:22 pm

Ain't that the truth, Duga?
Not going to cry until I do the lap.....not sure whether to wait a little longer til after the break in or just go ahead and do it.
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Re: Happy_Bummed

Postby Motorhead » Fri Apr 27, 2012 2:12 pm

Ramatam wrote:Ain't that the truth, Duga?
Not going to cry until I do the lap.....not sure whether to wait a little longer til after the break in or just go ahead and do it.


Lapp it in !!

If for some reason entire rifle needs to go back to Crosman again, a patch with some Quick Blue run down bore with BLACKEN it back up so your polish job would never be seen or detected !
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Re: Happy_Bummed

Postby Ramatam » Mon Apr 30, 2012 6:17 am

Good advice Motorhead...
I checked it once more this weekend. the winds calmed and the sun came out on Sunday and I put 8 shots through one small 1/4" center-to-center hole at 20 yards. That kind of took me aback. I was like, what's going on here, I've never put 8 shots through one hole...maybe 5 but not 8. So I think I'm going to slow my Mustang down a bit and shoot some more before passing judgement. I've heard that it takes a little while to break in a barrel....this barrel is starting to show very promising signs. Then I'll do some 50 and 100 yd tests (wind permitting); if things aren't acceptable then I'll lap.
The only other thing to do now is to go in and Blue Loctite the hammer stroke threads in order to keep things from creeping. I had done that on the other action and I'll have to do it again since this one is new ...and it is changing.
Anyway starting to feel better about things, thanks for the input and stay tuned.
kp
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Re: Happy_Bummed

Postby Ramatam » Mon May 07, 2012 6:15 am

Time to remove the "bummed" part of this topic heading. This barrel is really shaping up nicely and without lapping. I sent some more lead down it the past few days and when the wind finally died down yesterday I managed to get two magazines worth of pellets sent 50 yds downrange to a target.


Image

Eight shots into each target. Very light L to R cross wind. Refilled with air after each magazine to 2800psi. Shooting from the bench/sandbag.
Target 1: (left) 5/16" CTC ....
Target 2: 3/8" CTC....
Interesting that each flyer was in the same spot on each target....I was going to include the CTC for the flyer but did not measure each the same so I'll go back and remeasure and post but not sure it's necessary.

I'm not a terribly great shot but I have not had results like this even with 5 shot groups at this distance. This barrel is looking like it will surpass my old barrel. Very happy.
KP
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Re: Happy_Bummed

Postby Bill G » Tue May 08, 2012 3:59 pm

Man that's great news and progress. IS IT A FACTORY REPLACEMENT? Once that barrel settles in, you'll be MOA or better at 100yrds.
It is a dangerous proposition to believe that you can reason with evil.
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Re: Happy_Bummed

Postby duga » Tue May 08, 2012 10:08 pm

Flyers, where do they come from?

I think it's due to the occasional retarded pellet.

Somebody with a slo mo camera needs to do a test or something
.25 Mrod, HDD, depinged, tuned at 880 fps with jsb exacts (20 shots 26 fps ES)
6-24x44 BSA Tactical side AO with 10 yard increments marked on elevation turret cause I like to click
bipod and sling

Lots of firearms that collect dust
duga
 
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Re: Happy_Bummed

Postby Ramatam » Wed May 09, 2012 4:06 pm

BillG: Yeah, factory...actually they replaced the entire gun except the stock. Everything metal is new. :)
Hoping to shoot more and tune just a bit more. The ES is still high so I'll try using the velocity screw to see if it doesn't flatten things out a bit. Then, fingers crossed, I'll try for 100 yds...still tempted to lap.

Duga: Flyers come from that occasional out of round skirt or a dirty barrel. The barrel was recently cleaned so I think it was pellet deformation..or I was a lousy shot in the same spot both times and I guess i can't totally discount that. :?
Ramatam
 
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Re: Happy_Bummed

Postby Ramatam » Wed May 16, 2012 7:07 am

Jimmyk over in the Shot String Database thread asked me about lapping a barrel. I decided to answer his question here so as not to get too off-topic over there. This last weekend, not being entirely happy with the fliers I was getting in every target, I decided to bite the pellet and remove the barrel from the .25 and lap it. I followed Greg Davis' method for lapping a barrel.

http://www.network54.com/Forum/581291/m ... l---------

As per Davis, I used Mothers Mag wheel and Aluminum Polish and a brass or bronze bore brush, size .22. I would use a Dewey Nylon coated rod for .22/.25 which you can get at PA. I only had a regular metal rod which I wrapped with black Gaffers tape...it's a fabric based tape, not duct tape. You don't want to scratch or otherwise damage the barrel; air gun barrels are a lot softer than those in powder burners.
I took several 1.5-2 inch Mothers saturated paper towel strips and I rolled each, one at a time, onto the brush, taking care to completely cover the entire length of the brush. Use whatever length makes for a snug fit when rolled onto the brush. I took the barrel completely out of the breech and used a table top to stabilize it. You can leave it in the breech but I would suggest lining the breech with some paper towel to keep the mothers from getting up in there. Be sure and remove the O-ring in the breech end of the barrel before starting. Following Davis' protocol, slowly run the brush down the barrel ...do not exit either end for about 7 strokes. I count a stroke as going from breech to muzzle, back to breech. Pull out after the 7th stroke and notice how black it is! Run a couple of patches down the barrel to remove the residue and repeat , changing paper towels each time, until you've done maybe 28 to 35 strokes, again running patches after each 7th stroke.
I then ran patches soaked in Goo Gone until they emerged fairly clean then followed with several dry patches. NOTE: The Mothers will clog the O-ring channel and the air port so clean them out good with Goo Gone on a cotton swab then dry swabs. Coat the O-ring with Silicon grease, reassemble and sight in. .Use pb177's reassembly method to get everything realigned properly.

viewtopic.php?f=19&t=1896&p=10998&hilit=barrel+reassembly#p10998

look half way down the page....important stuff here!

NOTE: It will take 4-5 magazines (about 40 shots) to re-season the barrel and get groups to tighten up. I saw a big, positive difference by the 5th magazine! I got my old barrel back after doing this! :D It was well worth the time and it was kinda fun to do. :ugeek:
I would recommend it if you are having trouble with fliers or would just like to see if the groupings can be improved. Otherwise, if it ain't broke, don't fix it.
Hope this helps...KP
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