2260 Basic (crown)

2260 Basic (crown)

Joined: November 17th, 2006, 3:51 am

February 1st, 2011, 2:17 am #1

MODIFICATION 2: Crown

This adds on to the last post (which added on to the first post).
http://www.network54.com/Forum/275684/m ... ic+trigger

(Yes, do have a lathe and normally recrown with one. But for this, will recrown the simplest way; one that the average guy may feel is easy enough that they will attempt it. The good news is that no matter how you foul up, can always trim ¼ inch off the barrel and try again.)

This gun actually shoots well as it is, but am going to recrown it as a tutorial anyway (and if it shoots a little better, will count it as a bonus).

1.Get the front sight off. It is a plastic part, held on by just being a press-fit.
2.A block of wood makes the best removal tool. Ju8st make sure it is clean, slide it along the barrel, and smack the front sight.
[/IMG]
3.The sight will pop off. Pick it up (undamaged) as I intend to reattach it after recrowning.
[/IMG]
4.Notice how the barrel has a flat spot. The sight has a spot inside that matches that flat spot, so you'll be able to put it back on straight.
5.This is what the factory crown looked like. Pretty ugly, but the results of the previous tests weren't bad at all. Pretty is as pretty does, and even as ugly as this crown is, it shot pretty well.
[/IMG]
6.Chuck a round headed BRASS screw into an electric drill.
[/IMG]
7.Coat the brass screw with an abrasive compound. Can use automotive rubbing compound (not polish, the more abrasive rubbing compound for well oxidized paint), valve grinding compound, even COMET cleanser will work for this. I used a fine abrasive compound made for air bursh use when etching glass mixed with lithium grease because that is what I had.
8.Place the screwhead into the muzzle, run the drill at medium speed, and rotate the drill around in a figure 8 pattern.(understand, the screw head stays in contact with the bore, you pivot the drill around in that 8 pattern.)
[/IMG]
9.Take a look every minute or so. Are not trying to remake the whole end of the barrel, just the edge of the bore. Even, smooth, and polished are the key words. This was done in about 90 seconds of polishing.
[/IMG]
10.Clean the barrel.
11.Reattach the front sight. All I did was add a drop of glue and tap it back on with the same wooden block that was used to take it off.

TESTING:

Charged the rifle and fired 3 5-shot groups using the same H-point pellets used in the last test.

5-shot groups
20yards
Issue 'peepsights
[/IMG]

Cannot honestly say it is definitively better, but it started out petty good. Can say it is not any worse, and is likely to test out to be better, but it will take more shooting to be definitive.

Someday, will put that steel breech on the gun,s cope it, and see what it can do. But for now, it is much better than I expected it to be and it is kind of fun having a 2260 that looks pure stock but shoots this well.

Other than the time to do the two mods, the only $ expended was $5 for a 4-40 tap (used in the trigger mod). Brings the cost up to $89 and about 90 mins. of my spare time.
Last edited by gubb33ps on February 2nd, 2011, 1:21 am, edited 1 time in total.
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Joined: November 4th, 2006, 6:41 am

February 1st, 2011, 5:13 am #2

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Joined: November 4th, 2006, 6:41 am

February 1st, 2011, 5:15 am #3

MODIFICATION 2: Crown

This adds on to the last post (which added on to the first post).
http://www.network54.com/Forum/275684/m ... ic+trigger

(Yes, do have a lathe and normally recrown with one. But for this, will recrown the simplest way; one that the average guy may feel is easy enough that they will attempt it. The good news is that no matter how you foul up, can always trim ¼ inch off the barrel and try again.)

This gun actually shoots well as it is, but am going to recrown it as a tutorial anyway (and if it shoots a little better, will count it as a bonus).

1.Get the front sight off. It is a plastic part, held on by just being a press-fit.
2.A block of wood makes the best removal tool. Ju8st make sure it is clean, slide it along the barrel, and smack the front sight.
[/IMG]
3.The sight will pop off. Pick it up (undamaged) as I intend to reattach it after recrowning.
[/IMG]
4.Notice how the barrel has a flat spot. The sight has a spot inside that matches that flat spot, so you'll be able to put it back on straight.
5.This is what the factory crown looked like. Pretty ugly, but the results of the previous tests weren't bad at all. Pretty is as pretty does, and even as ugly as this crown is, it shot pretty well.
[/IMG]
6.Chuck a round headed BRASS screw into an electric drill.
[/IMG]
7.Coat the brass screw with an abrasive compound. Can use automotive rubbing compound (not polish, the more abrasive rubbing compound for well oxidized paint), valve grinding compound, even COMET cleanser will work for this. I used a fine abrasive compound made for air bursh use when etching glass mixed with lithium grease because that is what I had.
8.Place the screwhead into the muzzle, run the drill at medium speed, and rotate the drill around in a figure 8 pattern.(understand, the screw head stays in contact with the bore, you pivot the drill around in that 8 pattern.)
[/IMG]
9.Take a look every minute or so. Are not trying to remake the whole end of the barrel, just the edge of the bore. Even, smooth, and polished are the key words. This was done in about 90 seconds of polishing.
[/IMG]
10.Clean the barrel.
11.Reattach the front sight. All I did was add a drop of glue and tap it back on with the same wooden block that was used to take it off.

TESTING:

Charged the rifle and fired 3 5-shot groups using the same H-point pellets used in the last test.

5-shot groups
20yards
Issue 'peepsights
[/IMG]

Cannot honestly say it is definitively better, but it started out petty good. Can say it is not any worse, and is likely to test out to be better, but it will take more shooting to be definitive.

Someday, will put that steel breech on the gun,s cope it, and see what it can do. But for now, it is much better than I expected it to be and it is kind of fun having a 2260 that looks pure stock but shoots this well.

Other than the time to do the two mods, the only $ expended was $5 for a 4-40 tap (used in the trigger mod). Brings the cost up to $89 and about 90 mins. of my spare time.
I have a question to ask you if you wouldn't mind.

notoriouschris@gmail.com


http://crosmanairgunmods.blogspot.com
http://airgunmods.blogspot.com
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Joined: November 5th, 2006, 1:29 am

February 1st, 2011, 1:44 pm #4

How does one run the drill in a figure 8 pattern if the screw head is inside the barrel or are your polishing on the outside of the muzzle?
jtcrrt
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Joined: November 23rd, 2004, 12:15 am

February 1st, 2011, 2:48 pm #5

...but I'd be happy to answer the question.
What he's saying basically is to never let the drill stay still while you're spinning the screw. When doing this process by hand you're never 100% sure that the screw is on the same axis as the bore and if you just let it sit there and spin you may remove more metal from one side of the crown than the other, not good.

I like to move the drill in whatever random pattern suits me at the moment while turning and wobbling the barrel around, or, just hold the drill somewhat still and turn the barrel instead, lot's of ways to do it.

The whole point is to remove metal from all sides equally and random movements seems to do this as good as anything...short of a lathe.

Glenn in Texas

Last edited by SeeOhTwo on February 1st, 2011, 5:31 pm, edited 1 time in total.
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Joined: November 23rd, 2004, 12:15 am

February 1st, 2011, 3:47 pm #6

How does one run the drill in a figure 8 pattern if the screw head is inside the barrel or are your polishing on the outside of the muzzle?
jtcrrt
Shown here is a set of "crowning screws" I use, this set happens to be for .177 caliber.
The screw on the left is untouched, just like it came from Home Depot. It does a great job of polishing the crown on it's own but if you'll look closely at the screw on the right you can see it's been reshaped to go deeper into the muzzle. Simple really, you just chuck it up in a drill and shape it against a sanding disc.

My thought is that we sometimes push alittle metal into the barrel as we're working the crown and a smaller, reshaped screw can get in there further and smooth it out. It also terminates the rifling smoothly as it enters into the crown area. This, along with valve polishing compound, has worked really well for me.

Glenn in Texas

[/IMG]
Damn! I should have cleaned these things first...sorry for the dust n' grit!
Last edited by SeeOhTwo on February 1st, 2011, 3:49 pm, edited 1 time in total.
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Joined: November 5th, 2008, 8:23 pm

February 1st, 2011, 6:57 pm #7

actually cutting the inner portion of the crosman barrel or is the grinding compound just wearing it away?
And what would work for grinding compound if you didn't have access to the real thing?
Thanks
Ray
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Joined: April 12th, 2002, 5:26 am

February 1st, 2011, 9:13 pm #8

the compound/abrasive embeds in the softer material and cuts the harder one.

The technique is very old,wooden drill bits have been use to drill holes in bone, shell, horn, and even stone for thousands of years, by loading them with a sand and water slurry.

Common alternatives to lapping compound, suitable for lapping crowns, include those mentioned by Greg,and others such as valve grinding compound,toothpaste,bore polishing compounds and lead removing bore cleaners.
Last edited by classicalgas on February 3rd, 2011, 4:18 pm, edited 1 time in total.
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Joined: November 17th, 2006, 3:51 am

February 2nd, 2011, 12:35 am #9

How does one run the drill in a figure 8 pattern if the screw head is inside the barrel or are your polishing on the outside of the muzzle?
jtcrrt
The screw stays in contact with the bore, the drill PIVOTS around in that figure 8 pattern. IDea is to cut a new "crown" (the transition point between the flat of the muzzle and the edge of the bore). the pivoting pattern makes for a more rounded, even, transition.

Have used automotive rubbing compound, valve grinding compound, and in a pich have even used Comet Cleasner mixed with grease.

Slot in the screw head just seems to collect old usded compound mixed with the steel it cut; does no harm. If you had a round ball on a shaft, could use that (and if you have an old brass Crosman bolt handle, can use that as a brass ball.)
[/IMG]
Last edited by gubb33ps on February 2nd, 2011, 12:42 am, edited 1 time in total.
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Joined: April 21st, 2010, 12:36 am

February 2nd, 2011, 3:34 am #10

idea of using old Crosman bolt handles cause I have at least six of them and they will work great. Thanks for that tip Robert.

Carl
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