Questions RE: N560, Hunting Texas in the Summer, 30-06

[skipglo]

Take a small 6 pack cooler and plenty of ice. Maybe a cold pack over your barrel

And the 6 pack for your belly!

 

[esorensen]

Two three shot groups with three in a cooler with ice to the range, then three on the dash or open the hood and set them on the warm engine. 35*F-ish to around 135*F or so with the IR thermometer. Record zero's and speed. That should give you some idea. You can always shoot more…

 

[memtb]

For safety's sake….I do my load development on hot days (usually over 90 F) to be certain that they are safe on hot days. I then test them under conditions similar to what they will generally be used in, for velocities and groups! memtb

 

[coueskiller43]

I've been running N560 in the 6.5 PRC with 124HH. Was doing load development at 70 degree weather and was right at 3300fps. It heated up last week to over 100 so I went back out to verify the load and see if it would be a suitable for our deer season (it was 117 opening weekend last year). Velocity jumped up to 3370 and had a slight bolt swipe. No heavy lift. I believe part of the velocity increase is coming from barrel break in. The original 3300fps was rounds 40-50 on a new barrel. The 3370fps was at 120-130 rounds.

 

[Okie John]

We had what passes for a heat wave in western Washington last week, so I took a pile of ammo and my chronograph and to the range. All of these are full-power loads.

308 Winchester
One load using Hodgdon CFE-223, a 150-TSX, Winchester Large Rifle Magnum primers, and Lapua brass gained 35 fps going from 50F to 95F.

One load using Ramshot TAC, a 168-grain Hornady Match Boat Tail, and Winchester Large Rifle Magnum primers, and Lapua brass gained 25 fps going from 20F to 95F.

One load using Ramshot TAC, a 150-grain Hornady FMJ Boat Tail, and Winchester Large Rifle Magnum primers, and Lapua brass LOST 4 fps going from 57F to 95F.


35 Whelen
I left my Remington 700 in 35 Whelen and a handful of cartridges in the sun until they were uncomfortable to handle. A load using Ramshot TAC, Winchester Large Rifle Magnum primers, and Hornady brass picked up 134 fps with a 225-grain Sierra Game King under those conditions, so apparently there are limits to what TAC will tolerate.


30-06
180-grain loads using Ramshot Hunter, CCI 250 primers, and RP brass picked up 48 fps from 75F to 95F.

180-grain loads using Vihtavuori N560, Winchester Large Rifle Magnum primers, and Lapua brass picked up only 71 fps from 20F to 95F.

180-grain loads using Nobel Vectan Tubal 7000, Winchester brass, and Winchester Large Rifle primers in the 30-06 picked up 20 fps from 20F to 95F.

Now you know what I know.


Okie John

 

[QuietTexan]

180-grain loads using Vihtavuori N560, Winchester Large Rifle Magnum primers, and Lapua brass picked up only 71 fps from 20F to 95F.

I don't think "only" is the right word there That's a big jump!

 

[Veteran]

I don't think "only" is the right word there That's a big jump!

Yes, N560 is not temp stable especially at 95 and above.....I think he was being facetious with ONLY.

 

[Andrew Massi]

Why don't you build up some loads at a lower node if you're worried about them? Chances are you won't be shooting past 100yrds anyway, so you will have plenty of firepower. Take your current load along with you and if it works, use it.....if not, you have a backup. For what it is worth, I built a load for my 6.5wsm with N565 @ 75° and shot it yesterday at 97° and had no change in velocity....I know, not the same powder

All of the 500 series vv powders are double base and fairly temp stable- 560 is very much like h4831sc in speed and temp stability.

 

[Okie John]

The N560 load went from 2,695 at 20F to 2,766 at 95F. That's such a big jump in temperature that I'm not too worried about the velocity change, but I'm not going to load it any hotter.


Okie John

 

[Veteran]

From the OP's original data above, a 71 fps increase in velocity from 20F to 95 degrees is 0.94 FPS per degree change. N560 IS NOT TEMP STABLE.

Here is another poster who found the same thing with way over 1 FPS per degree change. Go to the bottom of his post.

https://www.longrangehunting.com/threads/powder-temp-stability-test-–-8028xbr-varget-h4350-rl19-rl26-n560.213938/

The documented tests that have been run on H 4831 SC show 0.36 FPS per degree change. Quite A big difference! H4831 is not close to N560 in temp. stability.

Here is some temp stability data attached on numerous powders. It does not include the VV N560, N565, N568, N570 powders, but my understanding is that of these, only N565 and N568 are more temp. stable. I don't care what the jug says on it. I'm talking about what you can see running your own tests.

I have had really scary results shooting Alliant's RL 26 and N560 in 100 degree weather with loads developed at 70 degrees in Michigan.
I'm talking about shooting 250 gr. .338 LM rounds at over 3400 FPS!!
(They weren't hammers either! Scenars.)

Probably had pressures over 70,000 psi to have that happen......too scary.
Quit right there.

 

[Okie John]

Thanks to everyone who replied. Based on this thread, I won't be taking N560 loads to Texas in the summer.

Thanks again,


Okie John

 

[QuietTexan]

So what are you thinking about using? If you can find any H4895 has worked well in mine.

 

[Okie John]

I've got some H4350, but I already had a bunch of ammo loaded up with N560 and wanted to give it a try.


Okie John

 

[Runnin N Gunnin]

Almost locked up a 6.5 prc on n560. Hotter issue of spectrum under 50 degree. Hunted in January and it was upper 90's. Shot once. Dead dear but almost locked the bolt. FYI. Shooting in Texas you better have the right load and right powder.

Hey Longtine, do you have any experience with powders that hold up well in the heat?