Temperature Sensitivity Experience N560 and RL-26

[cb4128]

I live in North Texas and shoot RL26 in several rifles - 300wm, 7 SAUM, 6mm Creedmoor, 22 Creedmoor.

I have always intentionally developed my loads in 90-100* temps in the summer to make sure they are safe in the worst conditions. After I find a safe load, I set my 200 yard zero, then verify drops before hunting season starts - usually in much cooler weather, 50-75* where I typically hunt. I've never chrono'd my rounds during hunting season to check what the velocity changes are, but I think I will this year. Temps where I normally hunt in the panhandle can range from 13*-115* throughout the year, so it would be a good area to test.

I have also used N560 in a 25-06 and it definitely gets you some extra speed, even over RL26. I did not notice any pressure spikes, but again, I'm developing loads at 90-100* to find my max, and to finalize my loads - so the worst case scenario is my velocity drops off when the temps get in the 30's in December/January.

I'm also using N560 in my 7 SAUM this year, I have a pressure test loaded up to test in a few weeks.

*For what it's worth, I've seen pressure spikes with both Retumbo and H1000 at this same hunting location, after I developed loads in 100* temps and the hunting rounds were fired during the hunting season - 30-50* temps.

I will try to document my results throughout the season with both RL26 and N560 to come up with some real world experience to share.

 

[DMP25-06]

By the way I was down on the Pecos near Ft. Lancaster and Sheffield there in Texas.

As Ben Rumson (Lee Marvin) said in the movie - 'Paint Your Wagon' ,

" Welcome to H**L Reverend ".

 

[BrentM]

Well great..RL26 is my plan for 7SS (have H1000 too).

I am going to have to begin load development on my 7SS in late August because that is when I will be back in the states for a few days and then back to Europe for work until the late October hunting trip. I can expect the temps will be much different where I am loading (Georgia - hot) and where I will be hunting in October (Idaho - hopefully not). I guess I could do barrel break in and load development in August and take a day or two to finalize my hunting load before we depart in October.

Thoughts fellas?

Idaho in October, depending on where you are, will be much much cooler. The good news about cooler is that you will not have to worry about a pressure issue. I would not be concerned at all. Get a solid load in the upper node, hopefully a wide node with a low sd, and check zero when you get there. Lately we have been shooting in 90-95 temps at the ranch at 5000 feet. I run a PRC with RL26 and its been excellent, zero issues.

 

[new2mud]

*For what it's worth, I've seen pressure spikes with both Retumbo and H1000 at this same hunting location, after I developed loads in 100* temps and the hunting rounds were fired during the hunting season - 30-50* temps.

Are you saying loads developed in 90-100F weather gained velocity/pressure at 30-50? How much?!

 

[parshal]

The question wasn't directed to me but I saw a 20 FPS gain with 570 from 45 to 13 degrees.

 

[cabelasken]

All I can say is be careful!!! I try to keep well below the curve for hunting loads and strive for a reliable load in all conditions. I have found that to maintain good accuracy, those loads that increase velocity more than 50 fps on a 100 degree day can sometimes interrupt the barrel harmonics enough in an ultralight barrel that accuracy suffers and those loads are removed from the gene pool. That said, my two best shooting custom lightweight hunting rigs like loads that are book max

 

[meatyrem]

From what I know about RL-26 is that others on here (other threads about RL-26 and temp sensitivity) is it has little sensitivity in the cooler temps but once you get above 80* it gets a little radical where pressures get high real quick. I personally don't have any first hand knowledge as I haven't loaded RL-26 yet. I seen a chart and can't quite remember if it was from hodgdon or not but one of the most stable powders (that have been discussed here) H1000 was one of the top ones with H4350 being the best.
me personally I do not worry about this very much as I don't see myself shooting any hand loads or hunting rifles above 80*.

 

[BrentM]

From what I know about RL-26 is that others on here (other threads about RL-26 and temp sensitivity) is it has little sensitivity in the cooler temps but once you get above 80* it gets a little radical where pressures get high real quick. I personally don't have any first hand knowledge as I haven't loaded RL-26 yet. I seen a chart and can't quite remember if it was from hodgdon or not but one of the most stable powders (that have been discussed here) H1000 was one of the top ones with H4350 being the best.
me personally I do not worry about this very much as I don't see myself shooting any hand loads or hunting rifles above 80*.

I shoot in 80 plus all summer. Not an issue if you are not on the ragged edge. I just broke in a new barrel shooting 90-95 degrees in the past 2 weeks. Over 30 rounds in the break in run and a sd of 8. It's the same load I've run for 2 years. Wonder if people are just pushing it to hard

 

[Carlos88]

Well great..RL26 is my plan for 7SS (have H1000 too).

I am going to have to begin load development on my 7SS in late August because that is when I will be back in the states for a few days and then back to Europe for work until the late October hunting trip. I can expect the temps will be much different where I am loading (Georgia - hot) and where I will be hunting in October (Idaho - hopefully not). I guess I could do barrel break in and load development in August and take a day or two to finalize my hunting load before we depart in October.

Thoughts fellas?

That's what I would do. Really no other solution. Chronograph the August loads and match in October.

 

[308win]

Stop using Quickload

Why?

 

[SixDemonBag]

That's what I would do. Really no other solution. Chronograph the August loads and match in October.

After talking with my bro, the plan is to be at the range when opens and it shouldn't be over 80 degrees first thing. I am also going let the barrel cool as much as possible and look into a barrel cooler. Seems gimmicky but some recommend it.

1st day is for fireforming/barrel break-in if my 40-degree shoulder brass doesn't arrive from Rich by then. I won't be worried about velocities that day and will just get some trigger time on my .257WBY and 30-378WBY while my fireform/break-in shots cool in between. I haven't decided which of those two I am taking as my backup gun.

On the evening of day 1, we will load up 7SS test loads, make adjustments and do another morning session on day 2, wash rinse repeat until I get the load I want. I have to leave the evening of day 4 back to the European hell hole. I Will check shot a set of the loads in Georgia in October (whitetail for 3 days) to make sure they are still good - no reason to think they won't be in cooler temps.

Also plan to resight in and note velocities at the Idaho range and adjust DOPE from there.

 

[Veteran]

Stop using Quickload

Just out of curiousity, what do you have against QL or what is your bad experience with it? I find it a very useful guide especially when you tune it using your actual velocity data from shooting.

QL like any tool, is only as good as the inputs and the time you invest in getting and putting in good data a parameters.

It really made impression on me when it caused me to measure the volume of my Hornady .338 Lapua cases which averaged
107 vs. my Lapua cases at 116.1. There is a world of difference in pressure and velocity at those two inputs for a given charge weight and QL can help you see what that magnitude is.

So understanding case volumes has been one big benefit. It can and does help me quantify pressure and velocity changes from seating depths, use of different bullets, and certainly to a large extent different powders.

And I find it very accurate once I get my brass measured correctly, input all my specific bullets, barrel length, and then chronograph my actual velocities to "tune it" to the specific lot of powder I am using as to its actual burn rate.

Different lots of powder can vary 5-10% in their specific actual burn rates vs. what the manufacter says.

So unless you calibrate your QL inputs for actual velocities with an adjusted burn rate entry, you won't really realize its
full potential. Once you "tune" it up, it works great.