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The Annoyed Man wrote:Oh, I forgot to add a few details about this rifle....

Noveske also modified the bolt by adding a stronger spring and an O-ring on the extractor, and they mounted a small "recoil spring" on the firing pin, which the guy told me prevents slam fires with commercial ammo. They also headspaced the barrel properly. Apparently the firing pin is optimized for M118LR, which has harder primers than commercial ammo. This supposedly increases the risk of a slam fire when shooting commercial loads. I asked him if it actually works, and he shrugged. We both grinned.

You picked out a holster yet?

Very nice rig there Tam, I'm sure you will enjoy it. Don't worry about velocity out of the 18" bbl, you won't notice anything significant. The one thing I have learned about velocity out of handguns or rifles over the years is that the faster it is just lets you know you missed that much quicker. Enjoy your new rifle and be sure to give us a report on it.

Oldgringo wrote:

The Annoyed Man wrote:Oh, I forgot to add a few details about this rifle....

Noveske also modified the bolt by adding a stronger spring and an O-ring on the extractor, and they mounted a small "recoil spring" on the firing pin, which the guy told me prevents slam fires with commercial ammo. They also headspaced the barrel properly. Apparently the firing pin is optimized for M118LR, which has harder primers than commercial ammo. This supposedly increases the risk of a slam fire when shooting commercial loads. I asked him if it actually works, and he shrugged. We both grinned.

You picked out a holster yet?

Man, I hate the idea of trying to conceal and carry this beast. It weighs about 9.5 lb without the scope. Tell you what though..... It goes into a tactical soft rifle case and fits on the floor of my back seat just fine.

More pictures:







http://swfa.com/SWFA-SS-5-20x50-Tactica ... 51642.aspx

http://swfa.com/Bobro-Precision-Optic-3 ... 47215.aspx

Look out Elm Fork! I'm going to be livin' large there on Saturday!

Good choice on optics and mount. SWFAs SS have proven to be good optics and the Bobro mount is top notch.

Lookin' good, I am patiently waiting for the Nikon M-308 4-16x42 to hit the shelves to put on my 24" match upper. Not too much fun to shoot that thing without any optics.

Dear Santa....

(Continuation from Andy's post)...................And..........................Results? I want to see those sub-moa shot groups, Chris

v-rog wrote:(Continuation from Andy's post)...................And..........................Results? I want to see those sub-moa shot groups, Chris

Sadly, they did not happen.

I tested a bunch of different loads....everything from Black Hills 175 Match to some M118 (not "LR") to some handloads. What I found was that the hotter the load, the better the rifle liked them. The former owner told me that the Noveske barrel is "optimized" (whatever that means) for the M118LR, which is not the same thing as the M118 cartridge. Both have 175 grain Match Kings on them, but the LR round is considerably hotter, "LR" standing for "Long Range." M118LR ammo is kind of hard to find these days, and it is pretty expensive when you do find it, because of the supply/demand economics of it. As I said, I did notice that it shot considerably more accurately with hot ammo. I have a handload consisting of a 175 grain Match King over 45.2 grains of Varget which it liked better than most of the other loads. There were two other decent performers. One was a 180 grain SST over a 42.4 grains of Varget. That's not even the hottest load for that bullet/powder combination in the Lyman manual, so I could pump that up quite a bit more and see how it does. The other good performer was, surprisingly (or not), the 165 grain Federal Fusion commercial hunting load, which is a kind of a hot load. I've always gotten pretty decent groups out of this ammo, in three different rifles now, and I'm pretty impressed with it.

Anyway, given that the rifle is supposed to work best with M118LR, and given that cartridge's rarity and price, I'm going to try and "reverse engineer" a handload which duplicates its ballistics to see how it does.

There was one other thing that affected my shooting that day (actually I shot it on Thursday, not Saturday), besides my unfamiliarity with the rifle, and trying to get the scope zeroed, etc., was that the gunshop that had Dura-Coted the barrel had also improperly mounted the YHM Phantom flash hider. They put the crush washer on the wrong way so that it wouldn't crush down all the way, and consequently the last 180º turn on the threads was not available to them. So the flash hider—which is also a compensator—had all of its vents pointing down and to the sides, instead of up and to the sides. Don't every let anybody tell you that one of these flash hiders is not really an effective compensator. Every time I pulled the trigger, the muzzle bucked upward in a fairly disconcerting manner and it began to affect my shooting. I remedied the problem last night by ordering a Smith Enterprises Vortex flash hider for it. These do not need a crush washer as the unit is self tightening each time you pull the trigger. These are also suppressor capable for the "Wind-Talker" series of suppressors.

I could have simply bought a crush washer and remounted the original flash hider, but then I would be torquing it against the barrel to get it seated properly, and I didn't want to risk twisting the barrel too much. So there it is.

Just a quick update......

I ran several other new handloads through Brutus about 3 weeks ago, using BL-C(2) powder and magnum rifle primers. At the middle charge loads, it was noticeably hot, and there was evidence of primer flattening. With a hotter load (not all the way hot), I was blowing primers clean out of the primer pockets, finding the spent primer on the shooting bench surface. I stopped shooting that load.

It was obvious that these loads were really hot, not just because of the primers, but also the the recoil. I have the Smith flash hider mounted now, and it worked as advertised, but it felt almost like a magnum rifle. So here are my thoughts, and I would be interested in anybody's feedback.....

I kept pushing the velocity envelope because that was what I had been told by the guy I got the rifle from: hotter = more accurate for this rifle. BUT.......... rifle accuracy in my experience is a funny thing. You can have a slower load (say something around 2,400-2,500 fps for a .308) and have it be real accurate but lacking extended range due to bullet trajectory, then as you pick up velocity, your groups begin to open up. I've seen this in my bolt rifles. But then, at some point as the velocities increase, the groups begin to tighten up again. I suppose that, in the theoretical "unexplodable barrel," the cycle would repeat again and again, causing group sizes to increase then contract as velocities continue to climb (barrel harmonics, and all that). My bolt rifle has a 26" heavy barrel, which gives plenty of bore length for a powder to fully burn and drive the bullet to maximum velocity before exiting the muzzle, not to mention plenty of 1:10 rifling length to stabilize the bullet. It really likes 175 grain Matchkings.

This AR10 also has 1:10 rifling, but the barrel length is only 18"—considerably shorter than my bolt gun's. Also, this AR10 has polygonal rifling rather than the conventional rifling of the Remington 700, and I can't seem to find any information about the effect of polygonal rifling in a rifle barrel (as opposed to a handgun barrel) when compared to standard rifling in other barrels. In any case, with an 8" shorter barrel, it appears to be next to impossible to generate the kinds of velocities I get out of my bolt gun without also creating an unsafe condition, and so I am going to have to work up a slower load than desired and accept that the maximum effective range on this rifle will be less than that of my bolt rifle's.

The two powders I have on hand are Varget and BL-C(2), and I'll be trying both 168 and 175 grain Matchkings, of which I also have both on hand. Does anybody have experiencing loading .308 for AR platform rifles configured for SASS, and what do you suggest as a starting point using either of these powders and bullets?

I could be wrong here because I'm just guessing, but I think the problem of expanding and tightening groups as velocity increases might have something to do with the sound barrier. Each time you approach the next one the groups spread out, due to the buffeting from the sound waves, and then as you push through it they tighten up again.

Have you tried any M118LR?

Poly vs Cut should make no difference, other than, in theory, polygonal rifling yields a tighter seal as the bullet travels down the barrel.

Seems like a lot of factors would contribute to the low FPS, and I think you've figured most of them out already. That flash hider thing bothers me a bit too.