308R2 build

[pug]

After getting my 20" barrel from tp555 (fine job he did on it too), I finally got my AR put together chambered in 308R2 . It was raining when I left the house so didn't take the chrono with me but after the rain let up I squeezed off some 125gr TNTs with 23gr of w296 behind them and they really sizzled. I will load up some 150s that I had tried in the 16" to see how they compare. I am hoping the extra 4" of barrel will provide a significant velocity gain but with the fast powders I am not sure. Time to play

Happy New Year everyone!

[pug]

Hope to work up some more loads tomorrow for this. So far the velocity hasn't knocked me over with 2195 fps with the 155gr palma and W296 being the best. Kept hitting high pressure before developing the velocity I was expecting so I throated it about .025" deeper (I had done this to the 16") and will see what happens. Ran out of 4227 some time ago and that may be just about right. Told the wife I had to run to town tomorrow and she said "what to buy more bullets and powder?"...hehe she knows me so well.

[pug]

update 2/3/08

Throating lowered pressure slightly and going to leave the throat at 0.250" for now. It appears 2150-2175 is a realistic max velocity with the 155gr in an AR-15 and can be reached with several different loads. Barely made major with the 125gr TNT at 2602 fps but it was on the hot side. Accurate 5744 has been recommended as a double base powder because of its burning speed being slightly faster than 1680 but slower than w296. I can get 23gr of 1680 behind a 125gr TNT fully seated in the neck and was wondering whether the 5744 powder is as fine grained as 1680?

[pug]

tp555 made me another nice barrel in my wildcat 308R2 chambering. This one was a 16" carbine barrel and I assembled the rifle last night and loaded some ammo. Had some projects to do today but couldn't stand the rifle just setting there so went out and chrono'd some rounds just to give me something to think about the rest of the day. I am going to have a lot of fun with this one. The Sierra 155gr bullets clocked 2201 fps avg. out of the 16" rifle for a 5 shot string. Here is a not to good of a pic of the rifle.

Edited to add:

Got to try 110gr SP in the 16" carbine and they averaged 2688 fps with 23gr of W296.

[pug]

Still working up loads but for now the chronograph is busted with a bad sensor.

The last loads tested were Speer 125gr TNTs and clocked a respectable 2560 fps out the 16" with 22gr W296.

[pug]

Tried some custom made 178gr TNFB bullets this afternoon and had pretty good results. Had got up to 2133 fps when I had to stop. My goal was a power factor of 375 and made that right off the bat which isn't bad for a 16". The 147gr AP loads did as expected. Penetrated block walls with no problem with the core tumbling. Got two chronographs now to make sure I don't screw up the numbers again.

I have been asked about making barrels in this chambering. I wouldn't offer anything unless I know it is absolutely right. There is more to designing a proper functioning system than just having a reamer made and chambering a barrel. A third revision on the reamer may be needed for the M16s and I believe I may do something with the gas port location as it seems just a tad too far forward still.