Got my RRA NMA4 in today.  Pretty dang excited about it.  I just sighted it in for 200 yards and there are two local matches tomorrow, so all is right with the world.  I had an experienced shooter at one of these matches give me a recipe for 52gr Sierra Matchking with Win 748.  After shooting 55gr and 77gr bullets today (things I had on hand) I have high confidence in the 52gr performing very well.  

First question to the forum:  Does anyone have a recipe for 52gr Sierra Matchkings using 8208 XBR?  What about with TAC?  My gun is (NMA4) 20" bbl with 1:8 twist, and I am looking for a sweet spot to focus on when I work up my load (following Sierra's manual).

(I have 8208 and TAC on hand, so was hoping to get loads with those powders in addition to 748.)

Second question:  I picked up a leather sling at the fun show today and it is raw leather.  What oil or other substance do you all recommend as the best to condition, protect, and break in a new sling?

I may ask the reloading question in that forum, but I wanted to get input from high power shooters first.  Any suggestions on what has worked for you all (or what to avoid) would be very helpful.

I've also got an RRA NM, and 52 SMK's and 26.8 grains of Re-15 truly give me 5 shots that create one ragged hole.  It's the only load that I can get that small.  I hear quite a bit about the 52's and 27 grains of Re-15, don't hear too much about any other powders with them.

John Feamster put his load in his book Black Magic.  He used 25.0 gr of H-335 in LC case with Winchester primers seated to mag length.  Feamster used that load in a benchrest match and fired a .231" group at 200 yards through a 26" Kreiger stainless barrel with 1/8 rifling.

Marty

Welcome aboard to HP shooting!  the 52s do well on the reduced courses.   I use 26 grs varget over a remington br primer out of my white oak  1/7 A-4.  I have a RR on back order just waiting.

26.5 gr W748, Win Brass, Rem 7 1/2 primer. 2.250" COAL. No crimp.

26.5 W748, LC brass, Wolf primers. Shoots knots.

And nothing on the sling needed but time.
any treatment will do more harm than good

At what distances are you shooting the 52's? Are they good enough for 300yrd work?

I shoot the 52gr for reduced courses at 200 and 100 yards. I load them up with 24.0gr of RE-15 usually either in PMC brass or Sellier & Bellot.