Upgrade your precision chamber work with the PULL THROUGH CHAMBER REAMERS – Clymer Extension Shaft Only, HSEXT. This dedicated Clymer extension shaft is the factory-original replacement/companion to the Clymer Pull Through Chamber Reamer sets, giving professional gunsmiths and serious builders the reach and control needed to cut super-accurate minimum headspace chambers in .30-caliber match rifles. Brownells UK+1
Whether you’re finishing a short-chambered .308 or .30-06 barrel, or dialing in a match-grade chamber on a bolt gun or semi-auto, the HSEXT extension shaft is the backbone that lets your pull-through reamer perform at its best.
What the Clymer HSEXT Extension Shaft Does
The PULL THROUGH CHAMBER REAMERS – HSEXT Extension Shaft Only is the long, precision-ground drive shaft that connects your pull-through chamber reamer to a T-handle at the muzzle:
Designed specifically for Clymer Pull Through (P/T) chamber reamers used on .30-06 Springfield and .308 Winchester match rifles Primary Tactical+2GunSafe Club+2
Allows you to drive the reamer from the muzzle end while the rifle’s own bolt applies thrust from the breech
Gives you full control of the reamer rotation and feed, so you can feel cutting pressure and stop exactly when headspace is perfect
This is the same style of pull-through system military armorers have long used to cut minimum-length chambers, giving their shooters a real accuracy advantage on the line. Brownells UK+1
Built for Minimum Headspace, Maximum Accuracy
With the Clymer pull-through system, the extension shaft HSEXT helps you create tight, minimum headspace chambers on match rifles:
The bolt itself provides consistent forward pressure on the reamer while you turn the extension from the muzzle
When the bolt finally “drops” on the GO gauge, the chamber has been cut to that minimum-length spec Brownells UK+1
The reamer design (used with this shaft) cuts the shoulder, neck, and throat, helping prevent neck crimping and ensuring smooth ammo chambering Brownells UK+1
The extension shaft is what makes the entire pull-through process manageable, giving you the feel and control needed to sneak up on perfect headspace instead of overshooting it.
24" Extension Shaft – Reach, Control & Stability
Clymer designed the HSEXT with the ideal dimensions for centerfire rifle work:
Shaft Length: Approximately 24" (60 cm) – long enough to reach from muzzle to chamber on most .30-cal shoulder-fired rifles Brownells UK
Diameter: About ¼" (6.3 mm) round shank, sized to be both rigid and flexible enough for smooth operation Brownells UK
Delivery Weight: Around 0.068 kg (0.15 lb) – light enough to handle easily while still feeling solid in the hand Brownells UK+1
The length ensures you can comfortably work from the muzzle end with the barrel still in the action, and the ¼" round shank fits the recommended .22 Throater T-handle driver for positive control. Brownells UK
Engineered for Professional Gunsmithing Use
As part of the Clymer pull-through chamber reamer system, the HSEXT extension shaft is:
Made in the USA, built to Clymer’s long-standing standards for gunsmith tools Brownells UK+1
Intended for use with finish reamers only—your chamber should first be cut with a conventional finish reamer, then brought to final spec with the pull-through setup Brownells UK+1
Suitable for bolt-action and semi-auto rifles in .30-cal match applications Brownells UK
This extension shaft gives you the same style of tooling used by military and match armorers, now available for your own shop or bench.
Perfect Companion to Clymer .308 & .30-06 Pull Through Sets
While this product is the extension shaft only, it is designed to work seamlessly with:
Clymer .30-06 Springfield Pull Through Chamber Reamer Sets
Clymer .308 Winchester Pull Through Chamber Reamer Sets Brownells UK+1
Clymer thrust bushing (sold separately) which supports the reamer at the bolt face
Together, the P/T reamer, thrust bushing, and HSEXT extension shaft form a complete system for finish-reaming match-grade chambers to SAAMI spec with extremely consistent results. Primary Tactical+2Brownells UK+2
Key Specs – PULL THROUGH CHAMBER REAMERS HSEXT
From Clymer distribution partners and Brownells: Brownells UK+2Brownells Österreich+2
Brand: Clymer
Product Name: Pull Through Chamber Reamers – Extension Shaft Only
Manufacturer Part Number (MPN): HSEXT
Brownells / Crow Product No.: 184300311
Style: Pull-Thru Reamer Sets (component – extension shaft only)
Length: Approx. 24" (60 cm)
Shank Diameter: Approx. ¼" (6.3 mm) round
Delivery Weight: ~0.068 kg (~0.15 lb)
Compatibility: Designed for Clymer .30-06 and .308 Pull Through Chamber Reamer systems; for use on bolt-action or semi-auto rifles
Country of Origin: Made in USA
Why Choose the Clymer HSEXT Extension Shaft?
Essential component of the Clymer Pull Through Chamber Reamer system
Lets you drive the reamer from the muzzle while the bolt provides precise thrust from the breech
Built specifically for minimum headspace, match-grade chambers in .30-caliber rifles
Designed and manufactured by Clymer, a trusted name in precision gunsmith tooling since 1958 Clymer Tool+1
Ideal for gunsmiths and advanced hobbyists who demand repeatable, professional-level results when finishing chambers
If you already own—or are assembling—a Clymer pull-through reamer setup, the PULL THROUGH CHAMBER REAMERS HSEXT Clymer Extension Shaft Only is the precision, USA-made shaft that ties the entire system together and helps you deliver super-accurate minimum headspace chambers every time.
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