Question on aftermarket G20 barrel usage

[Kenk]

Do most of you use your aftermarket G20 barrel (KKM factory length in my case) for everything, or only for cast
Thanks

Ken

[sqlbullet]

Personally I use the factory barrel, even for cast.

IMHO...The issue with Glock barrels and cast bullets has little to do with the polygonal rifling, and everything to do with the fact that they are very over-size, and not just the chamber.

Cast bullets lead barrels most commonly not because of velocity, but because they don't fit well enough to seal the bore.  If they don't seal the bore, hot gas (plasma) passes around the bullet and melts the sides. 

Think of a plasma cutter.  If you don't direct and contain a plasma cutters gas through the channel you are cutting, but instead raise the nozzle and let it play across the steel, it does little.  Same with a cast bullet.  Hot gases against the very large base do little, but put the same hot gas and pressure through a small gap on one side of the bullet and it will melt the lead.  Copper allows more blow by, but with a melting point 3X to 4X as high as the lead alloys used for cast bullets, it is not affected.

For this reason we say to size the cast bullet .001" over actual bore diameter.  Unfortunately, most people interpret this as .001" over nominal bore diameter, don't check their barrel, buy .401" bullets and shoot them.

Both my Glocks, an early 29 and a Gen3SF 20, slug at .402".  That means no commercial cast bullets are anywhere near big enough.  Shoot a .401" cast bullet through a .402" barrel and you will get severe leading, no matter how the barrel was made.

I cast my own.  My molds drop bullets that are .403. I don't size them, just lube and I use a good lube.

Lately I have been powder coating bullets, in which case I do size them since the powder coat adds about .002" to the as-case diameter.  In this case I size them back to .403 in a Lee push through die I honed out from .401" to .403".

The real challenge comes for those guys that have barrels a bit looser than mine.  .403" is about as large a bullet as I can make work in 10mm.  Any larger and the case bulges where the bullet seats resulting in reliability issues.  In those cases an aftermarket barrel is the ticket.

To answer you actual question....If I had an aftermarket barrel, I would just shoot that barrel.  I would not switch back and forth.  And, I may one day invest in such a barrel.  The tighter bore results in slightly more velocity and often in better accuracy, as well as the ability to use more "off the shelf" components.

[Kenk]

Well said, Thanks again!!!

[SPDSR]

Hmmn so that means hardcasts like Doubletap and Underwood which are .401 really can cause Glock barrel issues? Everything is so contradictory with these types of loads!

[sqlbullet]

Could be.

Shoot a couple and check the barrel for leading...

[The_Shadow]

SQLbullet covered this one well...  I have several aftermarket barrels and I use them at time at the range or hunting for extra barrel length or other reasons.  If I'm testing bullets that start to show leading in the factory barrel, I can put the AM barrel in and shoot them which leaves the factory barrel clean for carry purposes for the return trip home.

The AM barrel can show differences in velocity when testing for comparisons.

[cgreth]

Use a KKM Precision barrel.   Never had any accuracy or reliability issues at all.

[Ridgerunner665]

I don't shoot cast, but I use the KKM barrel for everything.

G40, not a 20... But still relevant to the question asked.

[FLYDAD]

"I use a KKM factory length with my gen 4 model 20 with better accuracy and no issues. 

[tommac919]

I run the G20/3 with stock barrel for everything.... no issues

No leading if sized properly as mentioned AND 98% of my cases don't even need a full resize to pass a go-nogo gauge.  ( the few that do go in separate bucket for just the Glock )

Will say tho, there is a pretty good diff in the lower part of cases that come out of my Sig 10mm and the glock
Glock are about .432 and the Sig is about .426.

But i still get 10+ loadings of the cases even with the excess working of brass

[jazzsax8]

I use the KKM 6" in both the 20 & 40 mainly to extend the life of the brass.  While the KKM could be relied upon after X-number of rounds, the history of excellence in the sloppy by comparison Glock barrels are my choice for serious carry.