Home Forums Hunting & Shooting Ask The Gunwriters Chrono question re: cloudy day

I just chronoed a load from my Vanguard Back Country .30-06, 24" barrel. 180 Partition, 59.0 gr Hunter, WLRM, Rem brass, 3.339" OAL. I've never chronoed this load in this rifle before. Overcast, 5:30 pm, but direct view of the sky, unit 15' from the muzzle. No skyscreen. Alpha Master model Shooting Chrony.

3 shots, average 2918, ES 40. Wait, that's not right. I changed batteries and tried again.

3 shots, average 2908, ES 12.

Add the two strings together keeps the same ES, average 2913.

I need to try again in brighter light maybe? I'm nowhere near the lands at 3.339". Or could this be accurate? I'm 80 fps over Nosler #7 velocity at the same charge.





P

Pharm -

My O 33 was not designed to use diffusers. I have a new set of SK III and it will use the diffusers or not.

I always graphed in SHADE or cloudy WX when possible.

I wouldn't doubt your reading because of WX or time of day.

Jerry

PS

Cloudy days are better then bright days.

Remington brass is usually on the thick side, and you are using a hotter primer than the book,

Two strings, essentially the same results.

I see no reason to doubt them.

30-odd years ago Bob Hagel was getting 2900+ from the 30/06 -180 and MRP, from the 24" barrel of a Weatherby Vanguard.

Possible? Sure.

Too hot? I dunno.

Thanks for the reply.

The same load chronoed 2900 in another Back Country. I might be right on.




P

Damn, that's what I got Saturday afternoon with a new to me 300 win...around 2900 fps with 180 grain bullets with max loads. Second 300 win I've had with a sloooow barrel.

Jealous

In my experience light-screen chronographs (and in particular Shooting Chronys) are more accurate under cloudy skies.

Ramshot's data lists a maximum velocity of 2869 fps with one 180-grain bullet, the Hornady SST, using 60.5 grains of Hunter, at slightly over 59,000 PSI. That's from their 24" piezo test barrel.

Unfortunately, while they tested Hunter with a bunch of different 180's, they didn't test the Partition. But Partitions do tend to result in a little more pressure than average, and 2900+ doesn't surprise me, since I've seen it more than once from 24" barrels and 180's with Hunter. The pressure probably is a little more than 59,000, but so what? The only reason the .30-06's maximum SAAMI average pressure is 60,000 is really old rifles. In a modern rifle 65,000 PSI (the MAP of the .270 Winchester, among many others) isn't a problem.

Hey, a +p load...

Yep Bugger, I remember telling you that I had seen 'here', on the fire, loads for 180s @ 2900 fps.

IIRC this the second thread discussing it. Glad you found it.


Jerry

Duplicates what I got out of several of my 06s, with another powder and 180s... H4831SC.

Have any of y'all used this? Do you think it might help solve the light issue?

http://www.btibrands.com/product/ballistic-precision-chronograph-g2/

Hey Rev.

I'm not being critical. I didn't know anything about diffusers for many years and I didn't have any problems.

I graphed in the shade OR when cloudy whenever possible. I don't why there would/should be a problem now. I know we can't always graph in cloudy WX or shade so some would have to deal with that.


I got new Sky Screen IIIs and they are designed to use diffusers (or not) and so far I've used it with & without the diffusers and still no problems.


Jerry

Thanks. I gotta seriously look into getting one.