Bull Barrel Muzzle To Front Of Slide Fit

[soulbyte]

How tightly should a bull barrel muzzle fit into the front of the slide? My gun is Rock Island Tactical 40. I purchased a KKM bull barrel as a replacement. I acknowledge the barrel has to be fit. To see how tightly the barrel fits into the front of the slide I took the barrel muzzle end and stuck it into the front of the slide. I expected it to be oversized and would have to be lathed to fit. Surprisingly it slid right in and had a little play. 

Isn't the bull barrel muzzle end supposed to be oversized so the gunsmith can turn it down to get a tight fit just like a barrel bushing gun? It's not a lot of play at all but I was expecting for it to not fit at all. How much play if any is allowable?

Thank you in advance.

[zzt]

Unfortunately, not all slides are to spec.  The hole in the front of the slide is supposed to be .700".  I've seen them go as large as .710".  The OD at the front of the barrel should be .699" ~ .700".    When you fit the barrel, check for barrel spring.  If the barrel fits too tightly in the front of the slide it won't go fully into battery.   Carefully remove material in the three places it is hitting and try again..  When you get no springing you have the tightest fit possible.

 

If there is no barrel springing, check this.  Try to move the front of the barrel up and down while in battery.  If you get a tiny movement, no problem.  If more, the barrel will not shoot as accurately as it could.

[Brazos Custom]

O.D. diameter of the barrel should be 0.695-0.696. The barrel has to be undersize enough to let the barrel cam up in the slide during lockup. Blueprint spec on the slide bore I.D. is 0.699 +0.003.

0.699-0.700 slide I.D. works well with 0.695-0.696 barrel O.D. to allow full lockup with no play.

[soulbyte]

Thank you for the response gentlemen.

Inner diameter of the slide is between 0.700 and .701

 

Outer diameter of the factory rock island barrel is between 0.697 and 0.698

 

Outer diameter of the KKM barrel is between 0.695 and 0.696, but closer to 0.696

It's a surprise to me that the factory rock island barrel is slightly thicker than the KKM barrel. Looks like everything is within spec. 

I've learned some valuable information. Your input is much appreciated.

Edited June 1, 2022 by soulbyte

[zzt]

On 5/31/2022 at 11:18 PM, soulbyte said:

Thank you for the response gentlemen.

Inner diameter of the slide is between 0.700 and .701

 

Outer diameter of the factory rock island barrel is between 0.697 and 0.698

 

Outer diameter of the KKM barrel is between 0.695 and 0.696, but closer to 0.696

It's a surprise to me that the factory rock island barrel is slightly thicker than the KKM barrel. Looks like everything is within spec. 

I've learned some valuable information. Your input is much appreciated.

 

Not all bull barrels are round at the end.  I've had one that had to have material removed to fit in the slide.  A recent Nowlin barrel varied between .700" and .695".  It locks up perfectly with no barrel spring.  If you are going to work on 1911s and 2011s it pays to remember that there are variances.  For instance:  try fitting an old STI slide to a Caspian frame.  It can't be done.  The slide ways on the STI slide are a lot larger than the raw rails on the Caspian.

 

I learned all this the hard way.  Now I know several manufactures whose slides, frames, barrels, and parts I can count on to be consistent time after time.  So their stuff is all I use.  It saves a lot of heart ache.

[valerko]

This is good info , I'm trying to replace my comp barrel wit regular one in my BulArmory

[shred]

Bob at Brazos Custom did an article on fitting bull barrels to slides in Front Sight a while back.  Worth a read even if you are just playing parts-swapper.

Series starts June 2019