Reason for New Bushing/Crown work on slides - Pistolsmith
Pistolsmith

Go Back   Pistolsmith > Pistol Forum > Colt Pistols

Reply
 
LinkBack Thread Tools Display Modes
Old 07-06-2003, 01:17 PM   #1
Junior Member
 
Join Date: Dec 2002
Location: Midlothian, Virginia
Posts: 10
Reason for New Bushing/Crown work on slides

I keep reading about refitting bushings and crowning for accuracy. Is there a large difference in prework accuracy vs. the crowning/bushing? Does anyone have any examples/pics?

Also, what is the typical turnaround time and cost to have a slide refitted with a tighter bushing and have a different crown angle cut?

Thanks for any info you can give. I have a NRM Stainless Colt Commander and the bushing is pretty loosely fitted around the barrel and am wondering what the difference would be. Also, is this something that Colt would address under warranty?
 
Remove Ads
Old 07-10-2003, 02:19 PM   #2
Senior Member
 
Join Date: Jan 2003
Location: NC Foothills
Posts: 870
Accuracy

Howdy dutch! Good to see ya.

Retrofitting a match-type bushing will probably boost your accuracy,
but how much depends on how loose your present bushing to slide/
barrel to bushing fit is now.

There's also the matter of vertical and horizontal lockup in your
pistol. The fit of the barrel hood in the slide also has a bearing
on it.

Let your slide go to battery at full speed...not on an empty chamber,
please. Push down on the rear of the barrel firmly with your thumb.
If the barrel doesn't move, you have good vertical lock. If it barely
moves, you can try a slide stop with a .199 or .200 inch diameter
pin to take a little of the movement out.

Then, field-strip the gun, and lay the barrel in the slide with the bushing
in place. Check for fore-and-aft play in the barrel. Don't let the
barrel tilt...Just push back and forth. There should be very little
movement...about .003 to .005 inch in an Ordnance-spec pistol...About the
the thickness of a sheet of typing paper.

Find a cork or rubber stopper that will fit the bore pretty tightly.
With the barrel and bushing in the slide check for barrel rotation.
An ordnance-spec pistol will show just a little, but it shouldn't be
overly loose.

If your checks show a pretty good fit, a bushing will help. If not,
it will still help, but not much. A full-effect accuracy job addresses
those three points of lockup. Be aware that very tight clearances
in these areas can affect reliability when the gun gets dirty.

Barrel crowning is rife with different numbers, and it seems that everybody has their own pet shape and method. I've found that the
main part of the crown is to make sure that the muzzle is true, and the
crown evenly cut. If these factors are tended to properly, I would
have to bet that it would require a very accurate gun mounted in a
machine rest to see the difference.

Hope this helps answer your questions.

JT
 
Old 07-10-2003, 02:26 PM   #3
Member
 
Join Date: Feb 2002
Location: NW Ohio
Posts: 89
Johnny,

If you keep "learnin'" me all this stuff, I'm gonna have to use it. I can't afford to keep buyin' pistols to work on! :lol:

Be well!
 
Old 07-10-2003, 02:30 PM   #4
Senior Member
 
Join Date: Jan 2003
Location: NC Foothills
Posts: 870
Learnin'

Hey hey DUB!

Good ta see ya buddy. I went back and edited that post a little.
Haste and no coffee this afternoon is the culprit, I fear.

Come set a spell...We'll leave the light on for ya.

JT
 
Old 07-10-2003, 03:12 PM   #5
Senior Member
 
Join Date: Jun 2002
Posts: 1,559
The short answer: Most guns are mass-produced, having loose bushings and poor crowns.
 
Old 07-10-2003, 03:30 PM   #6
Senior Member
 
Join Date: Jan 2003
Location: NC Foothills
Posts: 870
re: Mass-Production

Quote:
Originally Posted by Dave Berryhill
The short answer: Most guns are mass-produced, having loose bushings and poor crowns.
Ah-yep....Sad, but true. A good drop-in replacement bushing for
off-the-rack pistols is the MGW. The OD is .699-.700, and fits
stock slides much better than most stock bushings...and the ID is
close enough on some barrels that it requires a little relieving
in the area under the spring plug to keep from getting into a bind.

A range pal had me to order one for his WW2 GI pistol that was
shooting groups in the 10-12-inch category. Everything else looked
good, and the bushing alone shrunk those to about 6 inches at
50 yards from the bench.

At 15 bucks for the bushing, it was worth it.

Cheers!
JT
 
Old 07-11-2003, 11:41 AM   #7
Junior Member
 
Join Date: Dec 2002
Location: Midlothian, Virginia
Posts: 10
Tuner....

Regarding the rest of the fitting, fore/aft, Hood fitting, pin fitting are wonderful in this pistol. When you place your finger in the barrel, you can move it side to side/up and down within the bushing. It is not the bushing moving either.

That being said, the pistol is very reliable and I know that a well fit bushing probably wouldn't hurt the reliability, but should help the accuracy.

Where would I find the MGW unit you discussed, is that a brownells part?

By the way, got your Private Mails, I have to admit that I had thought the same thing about our friend.....wink wink.


Semper Fi

TF
 
Old 07-11-2003, 01:24 PM   #8
Senior Member
 
Join Date: Jan 2003
Location: NC Foothills
Posts: 870
Bushings

Howdy again Dutch,

Brownell's part numbers for the drop-in bushings are:
584-579-434 (Blued)
584-579-416 (Stainless)

Before you order, measure your barrel near the muzzle, and the ID of your bushing at the front with a dial caliper and get back to me.

JT
 
Old 07-11-2003, 10:10 PM   #9
Junior Member
 
Join Date: Dec 2002
Location: Midlothian, Virginia
Posts: 10
Well, I did take the measurements:

Outside Diameter of Barrel: .577
Inside Diameter of Bushing: .580

It would appear that the majority of "looseness" would lie in the OD of the bushing to the slide.

Does that help?
 
Old 07-12-2003, 03:50 AM   #10
Senior Member
 
Join Date: Jan 2003
Location: NC Foothills
Posts: 870
Measurements

Howdy Dutch.

Sounds like you've got a pretty good fit on the barrel to bushing end,
and the MGW MAY get it a little closer, but not by much. The bushing
to slide fit will likely be much better, since the stock bushings run about
.004 to .006 smaller than the MGW's OD. Yours is problbly .694-.695
inch, and the MGW will be around .700

You'll probably see some better accuracy, though how MUCH better...
there's no way to know unless you try one. I like the MGW drop-ins
for the simple fact that they take the "rock" out of most pistols in the
bushing/slide area.

When you get yours, pay attention to how easily the recoil spring plug
snaps into place. If it gets into a bind , you may need to relieve that
area of the bushing. The small Dremel sanding drum does the job nicely.
(roughly .360 diameter) Go slow, and check it often. Remove only
enough to let the plug pop into position freely. If you get any live failures
to return to battery,(called Stem Bind) remove a little more.

Hope this helps,

JT
 
Reply

  Pistolsmith > Pistol Forum > Colt Pistols

Thread Tools
Display Modes


Similar Threads
Thread Thread Starter Forum Replies Last Post
reason for being... ant9101 New Users 6 11-16-2011 01:42 PM
Any reason not to buy the Eclipse Pro Target II? dennismccray Kimber Pistols 6 09-18-2005 10:12 AM
Crown City Arms oegil Gun Talk 3 11-17-2004 07:02 PM
Shorten Barrel & Re-Crown 10mm Workshop 8 08-06-2002 02:31 PM
Crown Royal Holsters Double Naught Spy Holsters and Belts 0 07-22-2001 06:23 PM

Top Gun Sites Top Sites List


Powered by vBulletin 3.8.7
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Search Engine Friendly URLs by vBSEO 3.6.1
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright © 1999-2012 Pistolsmith. All rights reserved.