I took the Ruger 77 Mark II out to the range today for the first time since buying it from Frank Martinez. I shot four shot groups with AA 3100, going to one grain over book max, but never got a group over ~1-1/2" at best. Projectile was the 120-grain Speer Hot Cor...

I then shot five rounds I had loaded with 64 grains of WC 860 (same powder as H870 or AA 8700) lit with a CCI 250. Even with the 10# trigger in the Ruger, the group was well under an inch.

In short, I am pretty amazed. I would have thought this powder way too slow to group well for the 25 and similar, but I guess we are never too old to learn. The velocities look to be about 200 fps slower than the 3100 loads, but accuracy trumps the rest of it.

Anybody else play with WC 860 in the 25-'06? I am wondering how it would work with the Speer 100s?

After seeing this and one other discussion of slow powder in the 25-06, I went out and tried some 8700 in the "Bob" with heavy bullets (117s) to see if I could get the pressure up for a clean efficient burn.

Will have to run it across the chrono to see the velocities look like. Quickload said slow, very slow.

Many years ago I tried it in the 7.92X57 and velocities were low until the case as FILLED to the brim. They were accurate though.

Someone gave me 16 lbs of Accurate 8700 and I had most of a jug of WC870 from years past so some uses would be good,

TCL, if you are talking about the 257 Roberts, your results may be disappointing. My experience with the 860 is that it only works in rifles that are well over-bore, like most of the magnums.

There are some guys that are using about 3-5 grains of bullseye and similar to get a cleaner burn, but I am not that brave.

I hope it works out for you...

Doubless

I am hoping that the case capacity to bore diameter will get the powder going. Will be close whether the expansion ratio will let me pull it off as I get to 100%. Did not have powder in the bore after any of the shots yesterday.

My 257 AI may be a better candidate to pull off the efficient burn.

Using Bullseye as a kicker would scare me. I use WC860 in the 223, but use 4198 as a kicker (that's what I have on hand). I have a Pressure Trace and worked the loads up carefully to ensure no surprises. I think a very fast powder could be unpredictable, whereas using one that is suitable for the cartridge, but on the faster end of suitable powders, would get the pressure up for a good burn without being unpredictable. The velocities I get are a little lower than normal, but it burns relatively cleanly and functions my AR. I haven't shot enough to really know how clean it is. I got the WC860 for $5/pound, which makes it tempting for plinking.

I started by filling a case with 4350 (way too slow, but known), then gradually substituting WC860 on top until it was all 860. That was just to ensure the 860 was properly marked (I have heard of surprises with repackaged surplus powder). A full case of 860 actually cycled the AR, but unburned balls (it is a BALL powder) dented the shoulder of the next case), developing about 40,000psi. Then I started adding 4198 over the primer. I'm happy with a load that gives 50,000psi so there's a safety margin, especially as the weather warms up.

If you know how your primer react, they MAY be a good indication of pressure, but you cannot compare different primers. My CCI primers (#400, not the thicker #41) are flat (though not excessively) at 50,000psi while some factory 5.56 primers (5.56 is higher pressure than 223 and what the CCI #41 is made for) are still quite rounded at 60,000psi. Unless you have a problem with primer piercing or slam fires, the #400 will give a better indication of safe maximum pressures.