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Range Report on the 8mm Steyr Long Throat
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Old 10-16-2008, 03:02 AM
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Default Range Report on the 8mm Steyr Long Throat

I wasn't pressing too hard for this rifle to be ready to make the Colorado trip, but since I was going to the range anyway, I thought I'd see if the barrel was at least "OK". I bought this barrel off of EBay a couple of years ago. It is a Carl Gustav custom barrel that was initially chambered in 8x68. I had to turn off the existing threads, re-thread and re-chamber it. It is a "bull" barrel of sorts, and in addition has a "choke" - an enlarged area for the last 3" of barrel. After finishing, the barrel ended up 23.25" long. I kinda had high hopes for it.

While I fully intended to put a 'scope on this rifle, I had yet to get the mount, rings, or 'scope. So... this range session was really just to get a 'feel' for the thing and make sure the barrel wasn't a piece of garbage.

The whole point of making the rifle with a "long throat" was to be able to shoot heavy-for-caliber bullets - Hornady 195s or Sierra 220s - from the necked-down .376 Steyr case. So, based on Optimal Barrel Timing theory and using Quickload, I came up with a range of charges for the Sierra 220 BTSP. The charges chosen ranged from 65.88 grains, -1% down from the node charge, to 64.55 grains, -3% down from the node charge. The powder I chose was Reloader-22. I also loaded up three 195-grain Hornadys, just to use to 'get on paper'.

As I did with the .375x.284 Win, I shot the bullets "round robin". Meaning that I shot one bullet from each charge in each of 5 'rounds'. That minimized the effect of "order of firing".

A quick check at 25 yds, and I moved the target to 50 yds and started shooting the 220s. Here's the target:



As I saw on the .375x.284 Win loads, the first shot out of a cold barrel on a cold day was predictably an 'outlier'. The only group where this doesn't look to be the case is the 65.55-grain group, however, the upper right shot of that group was a 'called' flier. Keep in mind, that these shots were shot with open sights. So... the crappy groups shot at 100 yards with the 'scoped .375x.284 Win can't be blamed on "the nut behind the butt". At least not this time. Actually, "it" gets better. All I wanted to do was "check the barrel out". Yeehaa! It lookes like there are only three shots in the 64.89-grain group. Let me assure you that there are actually 4! Two bullets in one hole is not too uncommon, but these two are almost exactly on top of each other.

From lowet to highest, the average muzzle velocity for each group is: 2556, 2569, 2587, 2601, and 2613 f/s. All of the 3-shot groups (excluding the cold barrel first shots of each), except the 65.88-grain group are GREAT as far as I'm concerned - even if they are at 50 yards.

From lowest charge to highest, the 3-shot group sizes are:

64.55-grains = 1.137" x 0.594",
64.89-grains = 0.535" x 0.202",
65.22-grains = 0.462" x 0.521",
65.55-grains = 1.146" x 0.790", and
65.88-grains = 1.125" x 1.695".

Now I gotta tell ya folks, I'da been happy as a clam with the size of the last group. But four of the five groups are darned respectable even at only 50 yds considering the sights. Again, I haven't "cherry-picked" the shots. All of the 3-shot groups exclude ONLY the first shot from a cold barrel.

So, I think I'll focus my attention on the 65.22-grain charge, and see how that shoots with a 'scope.

I'm stoked about this rifle and this bullet. AND IT'S A BOAT-TAIL TO BOOT!

Oh yeah, I forgot to tell ya - the sights were just taped on with electical tape.





This thing might be scary accurate once fitted with a 'scope.

Paul

PS - I just noticed that the annotation on the target indicates it was shot at 100 yds. That's wrong. It was 50 yds. I was "cutting an pasting" from the 375 target and didn't make the change.

Paul
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Last edited by gitano; 10-20-2008 at 09:36 AM.. Reason: Correct 100 yds
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8mm, 8mm slt, obt, quickload, range report


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