Barrel Throat Erosion — Reality Revealed
So what does a “worn-out” barrel really look like? Tom Myers answered that question when he removed a 6.5-284 barrel and cut it down the middle to reveal throat wear. As you can see, there is a gap of about 5mm before the lands begin and you can see how the lands have thinned at the ends. (Note: even in a new barrel, there would be a section of freebore, so not all the 5mm gap represents wear.) There is actually just about 2mm of lands worn away. Tom notes: “Since I started out, I’ve chased the lands, moving out the seating depth .086″ (2.18 mm). I always seat to touch. My final touch dimension was 2.440″ with a Stoney Point .26 cal collet.”
Except for the 2mm of wear, the rifling otherwise looks decent, suggesting that setting back and rechambering this barrel could extend its useful life. Tom reports: “This was something I just thought I’d share if anyone was interested. I recently had to re-barrel my favorite prone rifle after its scores at 1,000 started to slip. I only ever shot Sierra 142gr MatchKings with VV N165 out of this barrel. It is a Hart and of course is button-rifled. I documented every round through the gun and got 2,300 over 4 years. Since I have the facilities, I used wire EDM (Electro Discharge Machining) to section the shot-out barrel in half. It was in amazingly good shape upon close inspection.”
Tom could have had this barrel set back, but he observed, “Lately I have had to increase powder charge to maintain 2,950 fps muzzle velocity. So to set it back would have only increased that problem. [And] I had a brand new 30″ Krieger all ready to screw on. I figured it was unlikely I’d get another full season on the old barrel, so I took it off.”
Similar Posts:
- Throat Erosion Revealed in Sliced Barrel — 2mm of Lands Wear
- A Slice of (Barrel) Life — Inside Look at Barrel Erosion
- How to Create A Dummy Round to Aid Barrel Chambering
- How to Craft a Dummy Round To Aid Barrel Fitting
- Use Stub Gauge to Check Shoulder Bump, Monitor Throat Erosion
Tags: Barrel, Gunsmithing, Throat Erosion
Tom:
I Don’t know what you are doing for barrel cleaning/management, but you should keep it up. The defined profile (as best I can see on the web) of the freebore at the champher back to the neck diameter is very good for that many rounds!
I’ll hire you to clean mine!
1200 to 1800 is the norm for that Ctg.
Have you shot the new 6 yet?
Alan
Tom showed this section of barrel to me after the EDM slice, quite impressive to actually see first hand what “throat wear ” looks like . He has a few more rabbits to pull out of the hat in the future !
I wish there was a picture posted of a new barrel as a comparison. I’m not seeing any fire cracking in this barrel, or marks from the reamer. Without a new barrel picture as a comparison it’s hard for me to see the wear. This looks like a new barrel that’s only been fired 230 rounds not 2,300.
It looks like my barrel before I set it back after 2,000 rds. I think that it shoots better than when it was new.