30-06, unexpected chrono reading

[Anonymous]

I loaded up some 30-06 ammo for a friend of mine with Federal brass, Superformance powder and the 178 ELD-X bullet. The charge was 59.3gr, which is 0.4 below the book max of 59.7 (Hodgdon data) and right at the book max from Hornady data.

The Hodgdon data says 2840 fps is the expected speed from a max load and Hornady gives this load 2750 fps which is well in line with what you'd think from an '06.

My friend reported speeds of 2904 to 2962fps....which seems sort of improbable. The bolt lift and extraction were normal and the primers didn't appear cratered. I know SuperP can deliver higher speeds at normal pressure, but this seems very high.

He also chronographed some Federal Premium loads with 180gr ABs and got speeds of 2640 to 2682 fps... which seems rather dismal for even factory ammo.


Any thoughts?

 

[Guy Miner]

Barrel length?

I'm not at all surprised by the 2640 - 2682 fps from factory 180 gr ammo.

But that 2900+ fps stuff with the 178? Wow! Right up there with the 180 gr 300 Win Mag factory ammo!

Might want to try that load again - maybe it really is delivering 2900+ fps... How was the accuracy?

Guy

 

[PJGunner]

The factory ammo is in line with tests I have done on Winchester silver box 180 gr. Power points. If tose loads he got the high velocity from were 100 FPS less I could accept that so two questions. What was the lighting conditions at the time of the testing. Sometimes that can screw up a reading. At what distance was the chronograph from the muzzle of the rifle. It could be the escaping gases from the test load were more forceful versus the gases from the slower factory loads. I've run chronographs early in the AM and run a second test around noon time and sometimes the difference is quite noticeable. That can happen when you're working with up to five rifles in one day.
Lighting can be funny. Sunny one minute and sun obscured by a cloud the next can produce some very wild readings. Even the time of day cam make a difference.
Paul B.

 

[fightthenoise]

I get those speeds and more from Reloder 26 over a magnetospeed. Both in 178 ELD-X and 180 Partitions. I was surprised too. It’s a FULL case but no pressure signs so far. The magnetospeed has replicated quoted speeds on box ammo so it seems accurate.


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[mjcmichigan]

RL26 with 220gn SPH over magneto speed at 2690, no pressure signs. 22” barrel. (Neck-sized cases, shoulder bumped back 0.002” Near QL max.

So 178 moving faster does not shock me.

PJ’s comments could ring true as well.

Also, that bullet has a long taper. Less drag on the rifling...


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[Nimrod84]

I'm not sure what to make of the Hornady data, but it is definitely an anomaly with the posted results. Discounting the Hornady data, if the load is going into the 65,000 psi territory (270 WIN rated pressures) than an extra 60-70 fps from the Hodgdon data is very believable. Hodgdon lists a 180 Sierra at 57,600 psi with that powder - so there is room for additional speed.

Without details on the rifle or chronograph, I would ask the friend about lighting conditions / chronograph setup along the lines PJ noted. The factory ammo speeds are within what I would expect from a 22" barrel. The 58 fps spread on the reloads though are on the fence in my mind - could be indicative of varied lighting over an optical chrony / a loose strap on a magnetospeed or it could be from an untuned load that needs some playing with...

 

[30-338]

Hornady data for Superformane max is 59.3gr @ 2750fps for all Hornady 180gr/178gr bullets and start is 48.9gr @ 2300fps for 30-06.

Did you do any workup loads or chronograph?