Revisiting 6.8 SPC .

[RBHarter]

Not so much a revisit as a barrel swap and what a difference !

I assembled a bargain basement AR 3 yr ago and worked up a cast bullet load for it and after some false starts and some loads that came very close to doing what I wanted but wouldn't play nice in the AR I arrived at a load that mostly worked and delivered more than factory feed would . 3" at 100 doesn't make me warm and fuzzy and love a rifle . So the AR got shelved and the load was made up in bulk for a someday I will binge on this or shoot pigs up close or something .
An opportunity for a top shelf barrel and bolt came along at a price I was willing to pay . Man what a difference in fit and finish between Mossberg maybe Wilson seconds and an ARP !
I moved from the 16" carbine gas to a 22" rifle gas and from an M4 to standard straight profile also . The ARP is obviously heavier and makes the carry point move from the GI handle point to a balance point about 2 inches in front of the mag well . I'm good with that it's more comfortable to carry there and more familiar in feel (Model 12s and Mausers are more me) . The original sight was close enough that no vertical adjustment was needed from the OM but I had to buy the tool for the new setup , 2 ft low at 50 wasn't working for me . 10 shots of the old cast load was rather dismal also .

The swap is only a little more trouble than a Savage . A barrel vise and correct wrench are at that is needed as far as special tools go . A drift for the sight/gas block and an appropriate allen wrench as needed . Remove the upper from the lower and the bolt carrier group . Remove the sight/gas block assy and gas tube and muzzle device . Lock the barrel in the barrel wrench . I used a Midway vise block tool and unscrew the barrel nut . Now the barrel slides back through the upper reciever and it's out/off .
Having done this to change a fore end from the GI M4 style to the free float and replaced the front sight/gas block with a low profile and flip up sights I can see where the tinker toy modular thing becomes a money pit .
Just reverse order and assemble with new parts . Portion of a thread shim stock makes lining up the holes easier than trying to hit them with the torque window of 20-45 ft lb . (Subject to the particular nuts and receiver) .

POI of course moved because I removed the scope and the barrel is completely different .
The first thing I noticed was that instead of every case hitting the brass deflector and going forward at about 2:00 was that they went straight out at 3:00 . Not a big surprise the gas port is 4" farther down the barrel so the pressure is lower the action moves a little slower etc . The 5R barrel probably isn't the best choice for cast as it has very narrow lands . The original cast loads were used to get the sights back close and as a base line . 6" at 50 yd was not terribly encouraging but it should also be noted that the bolt was changed in the carrier and basically the entire rifle was disrupted . So I regard the first 25 rounds as being used to "settle" the rifle .
The last 5 closed that up to 3" or so but the barrel wasn't pretty .
Copper wash is the bain of my cast shooting .......... A thorough scrubbing and copper solvents made me less than happy so I bought a few 90 gr HP . Sold as Gold Dot surplus they're cheap . 5 loads 25 rounds total 2 loads inside an inch . I'm happy now !
I just have to get the copper out again and I'll shoot some more cast with H4198 vs H322 .

[Ranch Dog]

I enjoyed the details of your work RB!