How fast is too fast for .308 Winchester?

[thump_rrr]

With the factory barrel on my Savage 10BA I was shooting 2625 fps loading 44.1gr of Varget over a 175SMK WITH BR-2 primers in Lapua brass.
This is well above the Sierra manual 41.7gr 2500fps.
It was good enough for 600M which is the longest distance we shoot.
I will add that I got 4,700 rounds out of that factory barrel. Accuracy did drop off considerably over the last 700 rounds while I was looking for a replacement barrel.

I now have a 24” SS IBI barrel with 1-10” twist and 5R rifling.
I installed the barrel myself and it closes on the Go Gauge perfectly and doesn’t close on the No Go Gauge. Yes, I removed the ejector when headspacing.

I didn’t have any 175SMK’s so I loaded some 178gr Hornady HPBT match to magazine length.
I dropped the charge to 43.5gr of Varget with everything else staying the same.
This is slightly over the Hornady manual maximum of 43.2gr at 2500 fps.
I was seeing between 2688 and 2711 fps so I stopped even though there are no pressure signs and I will do a new ladder test starting from the ground up.

All rounds were loaded to magazine length 2.860

 

[Charlie98]

How fast is too fast? I've got some Hornady 110grn TAP that comes out of my 16" M1a at 3130fps... so if that's what you are gauging it on, I think you'd be OK. A target barrel is just that... a very specialized, consumable part. I don't think 2700'ish FPS from a ~175grn bullet is out of the ordinary, particularly if you need it to go the distance.

I've got a 24" Savage 10 TAC... with probably 500 rounds down the tube, some of those fairly rapid fire (for a bolt gun.) I would expect issues with throat erosion before I'd worry about a worn bore.

 

[Varminterror]

When it comes to internal ballistics: Speed is a result, pressure is a problem.

I would recommend you to follow through with your plan to rework your ladder, but to find the nodes. I’d also recommend finding your land-kiss-length with that bullet and seat accordingly, not just taking mag length or book value.

If you’re below book max, not getting bolt click, not getting flattened and flowing primers, not seeing excessive head stretch, then velocity alone is not a worthy independent measure for overpressure condition.

Sounds like you just got a fast barrel. It happens. I had one barrel out of 3 I had made at the same time, same reamer, same smith, headspace and kiss length both within 1/2 a thou, nodes in the exact same windows… two were within a couple fps, which was in line with 6 other barrels I’d had prior - but the 3rd barrel ran ~160fps faster than the other two, way faster than it should have been. But counterintuitively, it ran stable for about 500 rounds longer than any of my other barrels for the cartridge had lasted… no complaints here and I didn’t look the gift horse in the mouth.

 

[25-20 WCF]

The supplier of Varget lists a maximum load of 45.0 grains of that powder over a 175 HPBT for 2690 fps at a pressure slightly below the maximum for the cartridge. It appears to me that the OP’s velocities are in the ballpark for a maximum load with his components in his rifle, although it never hurts to be extra careful.


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