RL-16 temp stable?

[7mm-08 Freak]

I’m not sure why but I was under the impression that reloader 16 was temp stable. I’m shooting it in a 6.5 Creedmoor and I lost 75 FPS from 100°F to 55°F today. I know that even the temp stable powders lose a little bit, but in my opinion, that’s pretty drastic what say ye sniper hide?

 

[spife7980]

It’s incredibly temp insensitive in my testing. Got any data to present?

 

[7mm-08 Freak]

I’m shooting it in a short barrel 6.5 Creedmoor and I was getting 2525 back during the summer and I shot it this afternoon and it shot 2450. The SD is right where it always was. It just slowed way down.

 

[.505gibbs]

What was different about the ammo you shot today vs your previous ammo and data collection? Was it virgin brass from the first data point, different powder lot, different lot of bullets, similar bore conditions? A slip up on your reloading process?

 

[7mm-08 Freak]

Nothing changed same brass I had 200 ready to go. They were all once fired all of them full length sized then neck sized with Redding bushing dies. all of ultrasonic cleaned then corn cob, same primer, same bullet same seating depth to my knowledge they were identical, but they were dang sure slower by 75 FPS. The only thing that changed was this summer when I discovered that load they were shooting 2525 with one of the Garmin units and today they were 2450 the SD and the ES were almost identical. Just a whole lot slower. Roughly a 50° temperature swing Fahrenheit.

 

[.505gibbs]

Something is off then. In my experience the newer Alliant powders are solid in the temp sensitivity department.
Did you use a different chronograph to measure? Not that it should make a difference if both are functioning correctly. Definitely not a 75fps difference.

 

[LRDD]

I've been using RL-16 for a long while and never experienced this. Something else is up.

 

[stello1001]

I mean, don't environmentals change??? The air is more dense now so wouldn't the bullet travel slower through it? I'm no expert but just spitballing ideas here...

 

[straightshooter1]

I mean, don't environmentals change??? The air is more dense now so wouldn't the bullet travel slower through it? I'm no expert but just spitballing ideas here...

Yes, but not much at the muzzle.

 

[7mm-08 Freak]

I've been using RL-16 for a long while and never experienced this. Something else is up.

I’ve been using it for a couple of years and I’ve never seen this. Either only thing I can think of is, I opened a new bottle, but the lot was the same. Maybe I did something that I didn’t know that I did but that’s pretty rough to deal with 75 feet a second when it’s already slow at 2525 of course it’s a 16 inch barrel but still I can’t handle 2450 that’s just way slow.

 

[.505gibbs]

When you think about it’s only 51 mph
But on a serious note it could just the relative humidity of the powder.
When I have multiple 1lb bottles of the same lot I usually combine them into one container to avoid unwanted issues. 75 fps is still quite a lot for just changing bottles.

I’d run the test again and see if you can duplicate it. If so bump the charge up until you are back at your 2525.

 

[7mm-08 Freak]

When you think about it’s only 51 mph
But on a serious note it could just the relative humidity of the powder.
When I have multiple 1lb bottles of the same lot I usually combine them into one container to avoid unwanted issues. 75 fps is still quite a lot for just changing bottles.

I’d run the test again and see if you can duplicate it. If so bump the charge up until you are back at your 2525.

I shot it again yesterday and it was almost identical but while I was there, I had some loaded with H 4350 started at 37 grains because my chambers tight and ran all the way to 40 gr and in half gr increments. I was getting close on pressure at 40 grains, but it did throw a group of three at 2550 with an SD of 10 At 40gr of H4350. I think there’s still some more meat on the bone so I loaded up some more with 40.5 and 41.0. I’m gonna try today. I still have a few of the others that showed the original issue. I’m gonna shoot them again today as well. I to mix all my bottles together. When I buy em mainly because there’s so much room in those reloader bottles, you can easily put 2 pounds in one of them. I’ve got a 8 pound jug of 16 that’s never been opened. I might get a few out of it and see if it’s doing the same thing.

 

[tho98027]

Watch Erik Cortina's podcast with Brian Litz. Brian talks about how humidity can significantly affect powder burn in your brass and affect velocity/sd's when loaded in one atmospheric environment and the ammo is then shot in a different atmospheric condition. Unless your ammo is sealed around the primer and bullet, your velocity will change with your ammo because the moisture can escape your brass and change the powder burn. I think he said he experienced this when he loaded ammo at his home for the king of 2 mile competition and traveled to another state to shoot the match. His ammo was not the same due to the powder drying out in his brass cases because it was not sealed. Something like that. It was a pretty interesting podcast. Erik has been doing a lot of cool interviews over the past year. Fun to listen to.