BAD CROWN?????

[Gippeto]

Seems that dog WILL hunt after all. Happy to hear it!

Nice looking shooter too.

Al

[CajunHoss240]

UPDATE(5/23/2013:

     Yesterday I was at my girlfriend's parent's house and I used her father's pipe cutter to nip off the old crown and hopefully create a choke. Thus kinda worked but only at the end and created a high spot at the end where the metal deformed from the cut. So I chucked my 22" barrel into her father's drill press turned horizontal and proceeded to re-crown the barrel. I held onto the barrel with a shop towel and used a flat file to make the face perfectly flat. I then used wet/ dry 220 grit sandpaper and 3 sanded round, flat head, machine screws to shape the crown inwards I also removed the high spot with the file and sanded it smooth with the drill press. Next, I used 320 and 400 grit paper to finish the crown up. I buffed the crown with the end of a shop towel and some WD-40 and it turned out 99.99% mirror finish. I was so happy with the results that I re-polished the lead in with the 400 grit and buffed.

     I was so happy with the results that I decided to redo the crown and lead in on my Beeman 1073 RS2 sportman w/ .177 barrel installed. It turned out beautifully. The barrel is factory choked and shoots Gamo hunters very well. I have ordered RWS Superdomes for it just last night. Can't wait to see how much better it groups.

     Anyways, since my now 22" 2260 barrel (originally 23.5") was smooth and shiny, I thought, well theirs one variable eliminated. But then I thought what if try to fire choke the barrel? I realize that these barrels are probably button rifled and from ME courses I know that that leaves residual stress in the steel. I figured I would heat it to near or at the upper critical transition limit for steel and then quench it to shrink the barrel. I knew this from school but I got the idea to do it to my barrel from some guy on the forums. He, however, advised another guy to air cool the barrel ( annealing) not quench the steel. I decided to quench for more choke and it worked out nice. What I did was use a blue propane torch - like that used for copper pipe brazing-  to heat up the last 2 inches red hot and tappered the heat back about 4 inches. I did this to create a gradual choke. after I got the barrel heated evenly, I quenched it in a glass full of iced water. I pulled a patch through with my trusty double dental floss and .177 Hunter pellet weight and sure enough it was choked at the end. Only problem was that I used water instead of oil. I wanted to use oil but I didn't want to risk it catching on fire in the garage and/ or waste a lot of her father's oil just for a barrel. Plus motor oil has lots of additives that could have impregnated themselves in the steel and yielded a discoloration.

     As it were, I recrowned and sanded the barrel to ensure perfection. Later, I shot Beeman FTS, H&N baracudas, and crosman HPs at 25yds to see if the groups were better than before. Sadly, the barrel still didn't like them. So when I got home I decided to polish the internals of the barrel a bit and clean the inside of the barrel that had been choked to see if that helped. I used Crest proHealth toothpaste mixed with  10W30 non detergent oil applied to a patch and worked it up and down the barrel. It was a very tight fitting patch as to conform to the rifling. It removed the quenching surface slag and probably smoothed some of the high spots in the rifling too. I cleaned the whole barrel with brake cleaner and scrubbed it real well with a brass brush and patched. I then ran an oil soaked patch and dry patches till squeaky clean.

     After this I tested the pellets again. The groups shrank in all three types about 1/2 inch@ 10 yds! Crosman HP's were shooting 1". FTS's printed same hole with 3/4 flyers after barrel got dirty. And Baracudas were at 1.25" consistently with some making .25" groupings withing the large group. I pushed a pellet through and measured 5.52mm from the 5.53mm previously. Not great but better than no choke at all. I have yet to get to try RWS superdomes ( its favorite pellet) as I had shot them all up prior to the work. But I am sure the .25" ragged hole groups I was getting before will shrink considerably @ 10 yds. I believe this because my crown wasn't as perfect as it is now and there was only a choke at the breech and now there's one tapered to the muzzle. I am excited to get my superdomes in and test them out! I will post pictures of the groups or make a video for you all when I do. here are some pictures of the two crowns an the lead in on the Beeman and the 1322.

[CajunHoss240]

The previous picture was the Beeman's crown. Now the crosman 2260 barrel crown.

[CajunHoss240]

here are the rifles side by side. I love how light my 1322 carbine is compared to the Beeman!

[KevinP]

Nice job ...   

[Crosshairs]

Nice job ...   

x1

[BDS]

X2