Winter load vs summer loads

[AWLEAPHART]

.284 Win. RL 17. 25” barrel
60 degrees
53.4 2888
53.6 2899
53.8 2905
54.0 2914
54.2 2933
54.4 2962

75 degrees
53.88
2916,2919,2923,2914

41 degrees
53.80
2876,2881,2878,2874.

Gun is grouping good but was wondering how you guys adjust to the velocities change from winter to summer?

A Leaphart

 

[gunsandgunsmithing]

.284 Win. RL 17. 25” barrel
60 degrees
53.4 2888
53.6 2899
53.8 2905
54.0 2914
54.2 2933
54.4 2962

75 degrees
53.88
2916,2919,2923,2914

41 degrees
53.80
2876,2881,2878,2874.

Gun is grouping good but was wondering how you guys adjust to the velocities change from winter to summer?

A Leaphart

I use a tuner, Anthony...much for just what you describe. IME, a tuner does exactly what you asking for but with a much shorter learning curve

 

[Big Mc]

.284 Win. RL 17. 25” barrel
60 degrees
53.4 2888
53.6 2899
53.8 2905
54.0 2914
54.2 2933
54.4 2962

75 degrees
53.88
2916,2919,2923,2914

41 degrees
53.80
2876,2881,2878,2874.

Gun is grouping good but was wondering how you guys adjust to the velocities change from winter to summer?

A Leaphart

Get a Butch Lambert tuner and don't look back. Simple..Short learning curve.. Tommy Mc

 

[AWLEAPHART]

Thanks guys. I'm going to look into it.
A Leaphart

 

[Nature Boy]

I just git back from the range shooting my .308 at 500 yards. The load I woked up when it was 70 degrees was 0.2 mils low in the brisk 19 degrees this morning

 

[Rancher Mike]

Does anyone change the load at different temperatures to maintain the same velocities?

 

[Rancher Mike]

I would like to follow up with another question, applied ballistics has a program that allows you to chart your muzzle velocity variation and the program makes the necessary changes to the ballistics chart and the clicks that are needed to keep the same poi. My next question is at what point does accuracy suffer and a load change becomes needed? thanks Mike

 

[dkhunt14]

.284 Win. RL 17. 25” barrel
60 degrees
53.4 2888
53.6 2899
53.8 2905
54.0 2914
54.2 2933
54.4 2962

75 degrees
53.88
2916,2919,2923,2914

41 degrees
53.80
2876,2881,2878,2874.

Gun is grouping good but was wondering how you guys adjust to the velocities change from winter to summer?

A Leaphart

Depending on your chronograph these numbers might not be right. Some chronos if the light is different, they don't read the same. Just saying. Some guys tweak the powder load. I would of thought a 284 and Re17 would be a little more stable. Matt

 

[rap36case]

I am learning to shoot at 1000yards in high winds. I currently shoot a 308win, 26" with 1 to 10 twist, Shilen built, Manners stock. I am 6'2" and probably need adjustable LOP for prone. My load is Lapua palma brass, BR4 primer, 43.2 grains Varget, 185 OTM Berger with muzzle velocity about 2712fps at 80F.

Has anyone done a practical test for 308 with Varget on muzzle velocity as a function of ambient temperature from 0F to 100F? I am guessing 50fps drop from my system from 80F down to 35F based on observation.

 

[seymour fish]

.284 Win. RL 17. 25” barrel
60 degrees
53.4 2888
53.6 2899
53.8 2905
54.0 2914
54.2 2933
54.4 2962

75 degrees
53.88
2916,2919,2923,2914

41 degrees
53.80
2876,2881,2878,2874.

Gun is grouping good but was wondering how you guys adjust to the velocities change from winter to summer?

A Leaphart

A, You have answered your own question, if in fact your groups are acceptable across the temp range listed. You could model with Quickload and titrate powder chg against temperature spreads with a target of maintaining barrel time, to put a fine point on it. No experience with rl17, but wonder if it might ramp pressure dramatically at higher temps

 

[savagedasher]

Just a small move of the tuner is all it takes . Larry

 

[AWLEAPHART]

I have been using H4350 in the past. But I’m reload 3 different cartridges with H4350 and had 4 pounds of RL 17-I changed up.Also to try to get a little more push on the 168.
Matt I am using a lab radar/FX-120i scale. This has been my long range hunting rig. It was chambered with old .284 spec reamer. It does have a longer throat. This powder has been sitting on my reloading table for a while. It has Aug 3 2009 on it. That shows I never use the stuff.
A Leaphart

 

[JeffG818]

"Does anyone change the load at different temperatures to maintain the same velocities?"

No. I would much rather adjust my zero at the range to match shooting conditions.

 

[Depart123]

I am learning to shoot at 1000yards in high winds. I currently shoot a 308win, 26" with 1 to 10 twist, Shilen built, Manners stock. I am 6'2" and probably need adjustable LOP for prone. My load is Lapua palma brass, BR4 primer, 43.2 grains Varget, 185 OTM Berger with muzzle velocity about 2712fps at 80F.

Has anyone done a practical test for 308 with Varget on muzzle velocity as a function of ambient temperature from 0F to 100F? I am guessing 50fps drop from my system from 80F down to 35F based on observation.

It has been done by independent research. In short, the average velocity difference over the range you described was 0.45 fps per degree in a 308 using 175 grain Sierra's using 3 different lots of Varget powder. 0-40 degrees showed slightly less change while 40-100 degrees showed a little more.

Average velocity change for the same bullet with multiple powders over the same temp range was 0.51 fps per degree.

From my own observations and testing using infrared thermometers tracking barrel heat as well as velocity after every shot, I can say that nothing at all good happens below 40 degrees. SD's go to shit, even though average velocity is predictable. Every shot raised barrel temp by an average of 5 degrees.

 

[rap36case]

It has been done by independent research. In short, the average velocity difference over the range you described was 0.45 fps per degree in a 308 using 175 grain Sierra's using 3 different lots of Varget powder. 0-40 degrees showed slightly less change while 40-100 degrees showed a little more.

Average velocity change for the same bullet with multiple powders over the same temp range was 0.51 fps per degree.

From my own observations and testing using infrared thermometers tracking barrel heat as well as velocity after every shot, I can say that nothing at all good happens below 40 degrees. SD's go to shit, even though average velocity is predictable. Every shot raised barrel temp by an average of 5 degrees.

A very systematic and sound experimental approach. Thank you.

 

[BartsBullets]

Does anyone change the load at different temperatures to maintain the same velocities?

Mike,

Yes, short Range guys do it all the time.

In winter months I’ve found I need to drop to a slightly lower node to keep guns shooting.

Bart

 

[Rancher Mike]

Mike,

Yes, short Range guys do it all the time.

In winter months I’ve found I need to drop to a slightly lower node to keep guns shooting.

Bart

Thanks Bart! So it doesn't work to add more powder(muzzle velocity) to pick up the same summer-time node?

 

[BartsBullets]

Does anyone change the load at different temperatures to maintain the same velocities?

Does anyone change the load at different temperatures to maintain the same velocities?

Mike,

Having a labradar on the bench for 2 1/2 years has opened my eyes to a few things. Cold weather the velocities slow down and

Thanks Bart! So it doesn't work to add more powder(muzzle velocity) to pick up the same summer-time node?

Mike,

No, not what I’ve seen. I shot my BRI today in 19 degree weather. This summer I was running it at 2970 to 2980 with Varget. The same load produced 2930 today. Dropped the powder a couple of tenths to 2915 and it shot in a hole. While trying to go up to 2970 did not want to shoot.

I see the same phenomenon with my PPCs.
Bart

 

[yukonal]

"Does anyone change the load at different temperatures to maintain the same velocities?"

No. I would much rather adjust my zero at the range to match shooting conditions.

You'd be doing load development all over again.

My LR hunting 284 has a 4.5 moa come up at 400, with a 200 yard zero...at 70 degrees. 2875 FPS.

My last 2 trips to the range this past week (including today) were 10 degrees above zero. Needed 5.5 moa to get it right. 2830 FPS.

So the temp change, and the effect of a 60 degree temperature drop to the loaded ammo (in my range bag in the back of my truck), made a moa (4") difference in just those 200 yards!

 

[AWLEAPHART]

Yukonal,
I'm thinking load development in the warmer months 70 to 95 degrees and adjust MOA for the slower FPS in the winter months. I'm wondering going this route maybe keep a better group than doing the load development in reverse? To keep pressure down when it warms up.
A Leaphart