Reloading though out the year.

[deadlyswift]

I have been shooting Fclass (FTR) for about 1 1/2yr now. We do shoot year round, and here is what I am experiencing. I'm using Varget in 308win. All from the same lot! Many claim Varget isn't Temp sensitive. I'm convinced that it is! Here is what I have experienced though a full season of shooting Long Range Comp.

Jan. 2011: I found a load of 44.4gr Varget with the 185 Berger LR/BT bullet jammed .015. Velocities were 2735fps. Temps were in the low 30s.

March 2011: The load was exactly the same when I tuned things in Jan. except it's late March and Temps are now low to mid 70s. I started getting pressure signs and even kicked a cpl of primers out during a cpl of relays toward the end of a 20rnd string. So After that match I went back and chronographed the load. (rounds left over from the match) The load is now running over 2800fps. So obviously I backed the powder charge back down. I landed at 43.6gr (varget) putting me back at 2735fps. I shot this load though out the summer with temps from the low 70s to 102F. Accuracy did not change much at all. Some but still holding ten ring elevation so I didn't bother retuning things.

Dec. 2011: Things have been unusually warm this fall. How ever I was able to test one early morning with temps in the mid 30s. Vel are now running 2670fps with 43.6gr and accuracy has fell off too. So now it's back to a higher charge to put me back into my node.

Has anyone else experienced this?

I also found during this fall with some mornings being in the mid 30s and evenings being in the upper 60s the vel. and accuracy changes even during the same day. I did a test to see what would happen. In the early morning Temps in the mid 30s. I would fire a round, eject and let the next round cook in the chamber a bit. By doing this I did get velocities to go back up some, and accuracy came back, not as good as when the load is fine tuned but better than what it was. In the evening when the Temps got up to the upper 60s If I let the round cook in the chamber Velocities go up as well my groups open back up. If I don't cook the round in the chamber then Velocities are running very close to my summer load and accuracy is pretty much the same.

What are some of you doing to maintain Accuracy and nodes while shooting though out all four seasons? For me right now it's just keeping a well kept log of everything and trying to figure out the best way to stay on my node during the changing conditions though out the year. I'm just intrested in what others have experienced and how you have maintained your accuracy or if you even have too? During the transition of Spring, Fall, and Winter.
Thanks

 

[Chuckhunter]

Deadlyswift, All powders will change with large temp. variations, some a lot more than others but do not fear, you are doing the right things by shooting across a chronograph and keeping detailed records. One of the reasons most experienced hand loaders work up their loads in warm weather is two fold. Its generally easier to increase your charge slightly if you're loading at the range and secondly it's safer to loose some velocity rather than achieving a pressure spike and or case head separation or worse. If you preload your ammunition and take it to the range, those records will come in very handy, by allowing you to adjust for the predicted temps and then just dialing in your load. I guess my recommendation for you is to keep shooting year round and keep those detailed records and you'll be good to go. There is no powder that is immune to temperature change but by finding the one that is least sensitive you'll increase your window of accuracy from season to season. As far as leaving the rounds cook in the chamber, the same holds true if you have shot a lot of rounds fast and your barrel is hot, then your conditions change and you have to wait pretty long for them to return, I personally take out the round that has been sitting in the chamber and insert a cool one. Others my do differently but if only to achieve mental piece, I change. Good luck and keep doing what you're doing.

 

[BlackEagle]

In addition to the variances caused by the powder's reaction to change in temperature I think there is a change in the actual rifle as well. The accuracy nodes that we find using ladder tests are the result of fairly minute forces and I think the barrel will have a different preference given significantly different weather. Fine tuning a load the day before a match would solve both problems. Right now I'm trying to figure out how much work to put into load development for some ammo that I won't shoot until summer. I don't think I can expect top accuracy out of it, but it seems like I should be able to do more than just arbitrarily pick a velocity.

 

[necchi]

In addition to the variances caused by the powder's reaction to change in temperature I think there is a change in the actual rifle as well.

Bingo!

 

[deadlyswift]

Thanks for the replies. Right now I seem to be stuck on a hump. As far as getting to the next level of classification, or consistently increasing my scores. Seems I can look over the hump and see the other side but just can't quite get to that next level. Obviously improving my wind and mirage reading skills is what will get me to the next level, and next, and the next, and so on.... How ever there are levels that I have to over come at the loading bench as well. Witch is why I posted this in the reloading forum and not the comp. Better understanding things, or just getting knew Idea's to test can't hurt.

Chuckhunter,
Yes I agree with you on keeping detailed records. It is definitely Important! My idea or thoughts on letting the round cook in the chamber to try and increase the pressure came from conversation at a resent match. So I tested the theory while shooting over a chronograph. I done this to make notes. If I have predicted certain weather conditions for a match. Witch I have to do. There is no way I could load fast enough to shoot from relay to relay. I don't think it is even possible to keep up time wise for Fclass. Anyway... If I load for one weather condition and the weather changes on me. Witch we all know can very well happen. Or even Spring and fall weather you get cold temps in the morning and warm temps in the evening. So by letting my round cook in the chamber to spike the pressure could possibly keep me just enough in my node to not drop as many points, elevation wise. To add I'm talking about 1000yds. Mid range is a different ball game and I don't really even worry about these things for 600yd and closer. As far as shooting in the summer. No! I never chamber my round until I think I see my conditions, and I'm ready to shoot. If I chamber a round and see a change in conditions, I eject that round and lay another on the ramp until I see my conditions come back. I'm with you there!

BlackEagle,
You did touch on something that is interesting. I do agree with what you are saying shooting in the summer, and winter has definitely got to change how the harmonics of a barrel reacts to a load. With the barrel, action and everything else being cold it has to be stiffer than what it would be in the summer. In most cases I do have unlimited sighters at 1000yd. I do take advantage of that to heat, and or to foul my barrel. More less I will shoot sighters until my barrel seems to have settled down. Then I go for record.

dmoran,
I think you are spot on. I get aggravated with Varget at times. Over all and at this point I do think it is the best powder for the 308win and the 185s. Right now I'm at a point where I'm just searching to improve! I have my highest goals set! I know what I want to achieve, but I also understand there are many small goals that I have to achieve before I can get to my ultimate goal!!

Again Thanks for the replies!!!

 

[BlackEagle]

I think the nodes actually change season to season. And I think one rifle's node may change to a higher velocity while another rifle's node may change to a lower velocity during the same time frame. I am speculating, but the magnitude of these forces is small and I think the actual effects are pretty complicated. It could be similar to the case of "stacking tolerances" where the change in the powder and the change in the rifle may partially cancel each other or they may combine to create a greater overal effect.