View Full Version : What exactly is a drop in barrel?

June 22, 2011, 10:44 AM
I am guessing that "drop in" refers to a barrel whose specs are loose to the point that they'll fit.

I am interested in getting a Lone Wolf 17L slide & barrel. I also really like the CCF frame. CCF recomends having any barrel (except Glock OEM and their own), "fitted" by a gunsmith.


From the CCF website FAQ:

Fitting of parts


Will the parts from my pistol have to be fitted?
While original Glock® components are a "drop in" fit, WE STRONGLY RECOMMEND the installation of the components into the new replacement frame be performed by a certified & qualified Glock® armourer. All safety & functionality inspections MUST be performed by a certified Glock® armourer, as would be the case anytime you are re-assembling a pistol frame. Folks, please don't take shortcuts on this for the sake of convenience.

Is a gunsmith going to be able to do anything except alert me to a problem and tell me they don't fit?

June 22, 2011, 12:10 PM
You are correct in assuming that dimensional tolerances for a drop-in barrel is made to fit any gun, albeit somewhat loose. If you want to see what a drop-in looks like, just look at your factory barrel. Loose lock-up, loose barrel-frame fit, etc. I agree that it you want a top-notch job, get a barrel that has to be fitted.

June 22, 2011, 12:39 PM
"lose fit" is one possibility, but the term is also used to differentiate from short-chambered barrels. Those barrels will always need to be fitted by a gunsmith.

June 22, 2011, 12:58 PM
What will a gunsmith do - take metal off the places in the barrel (lug, I'm assuming) ?

June 22, 2011, 02:05 PM
A properly fitted barrel involves threading so there is a snug ,rigid fit .For something like a M98 Mauser the barrel is cut so that the end of the barrel and the shoulder both are snug to the receiver .More rigid - more accurate !
Chambering is done so headspace is correct .Often headspace is minimum for better accuracy .Throating , both length and diameter can be critical for accuracy.Then you can glass bed the action ! In any case you start with a barrel blank , nothing precut.
That's all for the best way !!

June 22, 2011, 03:51 PM
Usually, in a handgun, the drop-in barrel is one that can be installed by the owner without fitting. It will not be as accurate as a fitted barrel except by pure good luck.

June 22, 2011, 03:53 PM
Since he is talking about a GLock, there is no glass bedding, chambering, throating, or threading involved.

The gunsmith will ensure the barrel-slide fit is optimal, will make sure the barrel locking lug fits into the slide properly, and will make sure the slide comes far enough forward at lockup to reconnect the disconnector to allow for the next shot.