[Grimson]

I am trying to get an idea of the different chamber dimensions of the various barrel makes out there. Here are the 3 that I use.

10mm Lone Wolf 5.15"= .426"

9X25 Dillon Lone Wolf Conversion 6"= .429" (below the shoulder)

10mm G20 Stock 4.60"= .433"

[_The_Shadow]

Glock 29
Glock Factory 10mm 3.78" = 0.4300"
StormLake 10mm 3.78" = 0.4250"
StormLake 40S&W 3.78" = 0.4245"
LWD 357Sig 3.78" = 0.4245"
LWD 9x25 Dillon 3.78" = 0.4245"

S&W1006
Factory 10mm 5.00" = 0.4280"
Bar-Sto 40S&W 5.00" = 0.4255"
Bar-Sto 9x25Dillon 5.00" = 0.4255"

S&W 1066
Factory 10mm 4.25" = 0.4280"

Lyman Cartridge Case Gauge = 0.4245"
This is why I invested in the LEE FCD to use as a Pass-Thru-Die, some of my barrels are as tight as the cartridge gauge.

[Yondering]

Where are you measuring, and how? Many chambers are slightly tapered.

Are you just measuring the largest diameter of the fired brass?

[Yondering]

Originally Posted by Grimson

10mm Lone Wolf 5.15"= .426"
10mm G20 Stock 4.60"= .433"

Interesting data point here, this illustrates the tighter chamber of aftermarket barrels pretty well.

The smaller chamber volume* in the LW barrel is equivalent to seating the bullet .017" deeper in the Glock barrel.

Hopefully this helps more people understand why aftermarket barrels can sometimes cause pressure signs with loads that are fine in Glock barrels.

*By chamber volume, I mean the volume in the case when the brass has expanded against the chamber walls, with the bullet still at the loaded OAL.

[gofastman]

Where are you measuring, and how? Many chambers are slightly tapered.

important question!

A caliper will not give you a very accurate measuerment.
better break out your split-ball gauges and a micrometer (everybody hase these, right? )

also, those of you measuring your LWD barrels, please post when the barrel was purchased, seems like the older ones are tighter according to a few recent threads here on GT.

[robert91922]

IGB barrel w. full supported chamber: 0.431"

In fact, this is diameter of my brass bulged at maximum

[Grimson]

Originally Posted by Yondering

Where are you measuring, and how? Many chambers are slightly tapered.

Are you just measuring the largest diameter of the fired brass?

I am measuring just inside the rear of the chamber with calipers.

[Kegs]

G29 .40 S&W 3.78" bbl of uknown origin (possibly federal arms): .425"
G29 stock 10mm 3.78" bbl: .433"
G29 10mm 4.45" bbl (KKM): .426"

chamber diameter does not tell the full story however.

The feed ramp cuts into these chambers at a different depths.

The Glock is cut the deepest.
The (alleged) federal arms is cut less deep.
The KKM is cut the shallowest.

Only the KKM has adequate support for what I would classify as "hot" loads.

The chamber on the federal arms is actually tighter, but they cut all sorts of loading channels into it on the feed ramp as well as the sides of the barrel, as I suspected they wanted to mimic The Glock design (which is crappy). I wish they would have just used minimal cuts on it there so I could keep pushing the .40, as I have some fairly hot 200 gr. rounds loaded up in .40 s&w. I think I stopped a little over 1000 fps and may have loaded up to around 1100 or so, but I'd have to look through my notes.

Maybe one of these days I will break down and buy a real barrel for that - not sure.

The KKM has pushed 1300 fps average for the 200 gr. xtp max in the 10mm.

That was overkill for this length.

It will run the 135gr. Noslers 1700 fps all day long. Max on those was ~1800 average, 1834 was the highest speed recorded for that bullet - not bad for a easily concealable piece with only the 4 1/2" bbl., still 1800 is overkill. 1700 produces groups in the 1.5" category @ 25y. from a bench (10 rounds) It is by far my best load yet.

[Any Cal.]

.435" on a late model G20SF stock bbl. Goes to .436 right on the edges of the feed ramp.