Build No. 1: Part 8

The barrel disaster. At least Brownells had them on sale with free shipping.

Before I could take this project to the range and shoot it, I needed to finish-ream the chamber to proper depth. The gunsmith fit barrel had a chamber depth of .880″ and I needed to take that to .890 – .900″. I figured using the Clymer finish chamber reamer I got from Brownells would not be too, too hard.

My first problem was that the reamer has a 3/8″ square drive which is much bigger than I thought and I had no tap wrench large enough to fit it. Amazon had a nice Starrett tap wrench big enough and it was here fast via Amazon Prime (I sure do love Amazon Prime).

Tap Magic Cutting Fluid
Tap Magic Cutting Fluid

I started reaming, being careful to only turn the reamer clockwise. With 5 full turns made, I removed the reamer, cleaned off the chips, and applied more tapping fluid. To measure the chamber depth, I used a dial caliper placing the end on the chamber ledge and the body on the end of the hood. Those 5 turns didn’t change the chamber depth a bit!

So 5 more turns and I saw maybe .001″ deepening. 3 turns later I was making progress and had the depth at .885″. 2 more turns and the barrel was ruined. The depth was now .916″, way over the spec resulting in much too great a headspace. That’s unsafe because the rear of the case may not be adequately supported to avoid a blowout.

Dang, it!

From feedback on the forums, it appears that the early cuts were just opening the chamber to its correct diameter. That’s why several turns didn’t deepen the chamber much, or at all. Once the reamer had “hit bottom,” it cut very quickly and I didn’t check progress often enough.

Learning can cost money. But I was already not very happy with the way I fit the barrel hood to the slide. This is an opportunity to do that again, better, and then not mess up the final reaming.

If you’ve started partway into this series, you can find the beginning here.

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