I had been debating what ignition system to use. There are several out there, including Hank's, Rem UML, Arrowhead, and several others. I bought a Rem UML to check out that system, plus a friend has a GunWerks based on the same system. If you're not familiar with it (I wasn't at the time), basically it's a shortened 308 case (or a 45 ACP case) and it headspaces off the thickness of the brass at the flash hole. So, for my friend's GunWerks (which is not smokeless) I took a bunch of cases, sorted them by flash hole thickness, then set up a jig on my mill to make them all the same snug fit. In the UML system, the cut down case hold the primer and the bolt holds the case like it would any 308 case.
I already had a Encore Pro Hunter receiver, so I ordered the Arrowhead barrel (yes, quite expensive - some $1600 or so for the barrel and the whole system with primer modules, bullets, etc.) as a way to try out that system. The Arrowhead system uses little solid brass rimmed modules to hold the primer. With the Pro Hunter, the module just inserts into the chamber like any rimmed cartridge.
I could have made my SML using the Rem UML breech block system, as I have a couple of those breech blocks laying around, but I decided to go with the Arrowhead system because I was so pleased with how well the Pro Hunter barrel shot - it easily bested my friend's $12K GunWerks.
Yes, I am doing all the work myself. It's my first go at barrel work or stock work. I've been carefully studying how to do it for quite awhile now. I've read a lot of books and guides, and watched a lot of videos. I cut the tenon and threaded it as per the specs from Kelbly (super people, and very friendly and helpful, BTW). I indexed the shoulder so the bore curve is up when the barrel is seated. I used "Grizzly rods" from PTG for truing it.
Before working on the actual barrel, I took a piece of stainless steel bar about 1.5" diameter and a foot long, and went through the whole procedure first with that, to make sure I had the procedure down. I worked slowly and carefully, and it came out without any problems. I also ordered a 32" blank from Shilen, so I'd have plenty of room in case I screwed up either end and had to redo it.
My recently installed lathe DRO made a huge difference in getting all the cuts done accurately, plus I took a digital caliper and made a tailstock feed DRO from that. Everything got carefully hand-fitted for a perfect fit.
The Arrowhead breech block is 5/8-18, so once the receiver fit was perfect on the barrel, I drilled and bored the chamber area, then tapped it for the breech block, using only brand-new, USA-made taps; first a taper tap, then a bottoming tap. Headspacing is set by the chamber shoulder that the rim on the breech block bottoms out on. I initially cut the shoulder so the bolt would barely close on a module, but then I remembered that Luke at Arrowhead had also sent me GO-NOGO gauges for it, so I had to cut the shoulder slightly more so the GO would go. Luke was very helpful in providing info and answering my questions.
For this build, I ordered primer modules from Arrowhead that are .308 head, so they are a natural fit for a standard 308 bolt head. The Pro Hunter barrel uses different modules - they are a rimmed design.
If anyone wants any more details on any of it, just let me know.
)…….so I've got one being put together and will put some pics up when it's all said and done. I went with:
