Re-barreling to 6mm Dasher

So I have decided to re-barrel to 6 Dasher. Why? I have no idea seemed like a good idea… I may have been peer pressured into it by a bunch of 6th graders at the range one day. Just kidding, sort of. It actually came highly recommended by several shooters that frequent the range and many local matches. I pretty much trust these guys, they shoot a lot more than me, and a lot better, so I have no reason not to trust them. So after much debate, mostly with myself, I decided to bench the trusty old .260 and try on the 6mm dasher for size…………………………..its small, like really small. I guess I knew it was small, but when my brass arrived and I opened the box and actually held one in my hands, it’s small.





So as many of you know I’m a bit of a do it yourselfer. Long story short, I decided to take on the re-barreling myself. Not that I think I could do a better job than an experienced gunsmith, but rather just for the experience itself. I already have a lathe, not a very nice one, but a lathe nonetheless. I also have a bit of machining experience, mostly with CNC’s, but how hard could this be, really. LOL



Here is the gun as it sits in .260 form.





Barrel finally came in, it’s a Bartlein 5r 1-7.5 twist. Yay!!!





Here is a bunch of tooling that I have gathered for the lathe.



First step was getting the breech end of the barrel dialed in. this proved to be much harder than I thought it would be. There are many different methods to this, a lot of guys use tapered rods stuck in the end of the barrel, some guys use “grizzly” rods that have a bushing on the end of them sized to the bore, and probably about a dozen other methods that I’m not even aware of. You could probably ask 5 gunsmiths how to do it and you will get 5 different answers. Myself, being a somewhat rational person, I like to break things down. So what really matters here? The reamer needs to be in line with the bore, so it does not cut an over sized chamber, and the bullet needs to ultimately end up situated in the throat both concentric and tangent to the bore. That’s really it. How you get there, well that’s up for debate. I prefer the simplest path. Test indicator directly on the bore, this way there is no chance of “stacking” tolerances with bushings, rods, etc.

Now, take all that with a big grain of salt, because I have literally zero experience doing this, that’s just the method that makes the most sense to me.



Checking bore at the future throat.





Checking at future breech end.



Picture of my homemade spider. This is used to support the barrel at the muzzle end.





Here is a picture of the whole setup





Next we need to get some measurements from the action. With these we can calculate the proper clearances for the bolt and bolt lugs.





Facing off the end of the breech



I put some purple layout dye and scribed a line at my final tenon length, just so I don’t over shoot it.



Next I cut the thread major diameter and chamfered the end of the tenon.



More layout dye, and skim cut the threads, just to make sure I had everything setup to cut 16 pitch threads correctly.



Final cut threads



Test fitting the action, I also checked the thread pitch diameter with thread wires, but forgot to take a pic of that step.



Double checking alignment, making sure nothing moved while threading



Finishing the bolt nose recess



Let the reaming commence, this was probably the most intimidating part for me, but after doing it once, I don’t know why people make a big deal about it. It was probably the easiest part.



I forgot to take a pic of checking the headspace with the go gauge, it’s just a bunch of threading the action on and off a bunch of times checking the chamber depth with a go gauge and a feeler gauge.

Once I was satisfied with my headspace, just one last check to make sure everything is still lined up.



On to the business end.

Parting the barrel off to near its eventual 28” finished length



Cutting the 5/8-24 threads for the muzzle brake/ suppressor adapter.



Finished threads



Timing the brake, one tip, make sure you have ALL the carbon buildup cleaned out of a used brake before attempting to time it.

Don’t ask how I know this.



It’s a bit longer than the old 20” .260



First trip to the range, I was getting some impressive numbers off the magnetospeed.

I would say this falls into the “purdy dang good ammo” category



I shot about 30 rounds through it so far, and I think it’s showing some potential.

This was my best group, off the bi-pod with a rear bag, and I’m not the greatest group shooter that ever lived.



Thanks for taking a look.

Still plan to engrave the caliber, and chamber a 6.5mm creedmoor barrel.

More to come…..