re: Sighting in Rifle Question(s)

Any chance Turkish could have gotten 150 gr pills instead of 130?

All good ideas. You think my velocities are that far off of what I should expect for a 17” bbl? Theyre in line with Barnes manual if I assume 150-175 fps loss for 7” bbl difference.

The chrono indication that alerted me to pressure was a sudden increase in velocity. I had loads with 0.4gr increments and velocity would go up about 10fps consistently. Then at about the 48gr mark, velocity jumped 40fps for the same increment. Prior to that point, velocities were close to what I’d have expected (although not a ton of experience with shorter bbls).

Started to do water fill test last night and didn’t get to it. Quick Google search indicates others seeing 6% ish less case volume in Alpha. That’s 3gr, so not far from my observations.

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velocity jumped 40fps for the same increment.

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This happened once or a hundred times? I don't even think that would catch my attention. You can get that much variation with the same powder charge pretty commonly (not ideal but not uncommon either).

I just went a pulled my notes. This is for a .308 shooting 130ttsx over TAC in Nosler brass. shooting one shot at each charge from 48-51 grains in 0.3gr increments (which I know is pretty worthless but I'm just wanting to show the velocity jumping around).

Charge Vel. Vel. Delta from previous
48 3100
48.3 3070 -30
48.6 3115 45
48.9 3135 20
49.2 3129 -6
49.5 3120 -9
49.8 3141 21
50.1 3176 35
50.4 3196 20
50.7 3208 12
51.0 3237 29



When you say the bolt was sticky - are we talking maybe a little sticky feeling because you were opening it slow and thinking about it after looking at your chrono or had to hit it with a mallet sticky?

The point of impact should not change merely because the barrel is heating up, unless there's a pressure point in the barrel channel/action. if there's pressure point, usually, the rounds will progressively move further away from the from the original POI. Your problem doesn't sound like. I may have missed it, but has anyone else that's a trusted marksman shot your gun?? If so, what were the results? I'd bet the problem is "shooter based" or something else like loose scope rings/base, bad scope, pressure point w/ action/action screws, a ding in the crown or a bad barrel.

Is the barrel floated? If not you can easily free float it if you think there's pressure point in the barrel channel.

It's not uncommon for the first shot from a gun to have a slightly different POI than follow up shots, but that doesn't sound like your problem, either.

I don't cool my barrel when I'm sighting in a gun. I usually go on 2-3 prairie dog hunt trips every year and usually will shoot 100-150 rounds/day. I don't cool the barrel down during a pd hunt so I don't cool it when sighting it in. OTOH, I do change guns periodically to avoid potentially getting the chamber excessively hot and damaging it.

Compressed can be fine, might not be. Certain powders with certain cartridges, you can't stuff enough in there to overpressure it if it's too slow for the bore ratio. You can't put enough US896 in a 35 whelen to blow it up, for example.

A compressed load of blue dot in a .35 whelen and you might kill everyone within 15 feet of it when it goes off.

But is the blue dot example dangerous because it’s compressed or because it’s too much powder?

Because it's fast burning, and a whole bunch of it in a case with a narrow nozzle to push a narrow bullet through means peak pressure will happen extremely fast. All of the energy will develop in a small volume. So, blue dot isn't dangerous because it's compressed. It's dangerous because the volume vs bore dia vs burn rate math works out to kaboom in a bottleneck overbore rifle case.

Conversely, you can compress the ever living shite out of us896 in a small volume case and the result will just be a ton of muzzle flash, unburned powder, and terrible velocity. It burns slowly and there's no time and space.for it to burn, so it all ends up flying out the barrel.

The extreme example is black powder. You can literally fill the barrel up halfway with it, and the result will be more smoke.

Right. And that was my point. It’s not the compression part. That’s what I’d been unduly concerned about.

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It’s not the compression part. That’s what I’d been unduly concerned about.

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If you feel the bullet crushing powder when you seat it, it's compressed.

Some more data. No stickiness noted today. Headstamps looked fine. Forgot to hit the last button on the Xero chrono, that’s why only 2 velocities for the first charge. All 3 were sub 1” groups, but the 48.2 was noticeably the best. All pretty little triangles. Not too trusting of 3-shot groups, though.

I guess I’ll keep creeping up. Would really like to be over 3k.

47.8 - 2908.4, 2914
48.2 - 2954.6, 2952.6, 2959.6
48.5 - 2947.7, 2948.5, 2963.5