Thoughts on nodes...

[XTR]

Something that has occurred to me since what I will call the end of the 2013 competition shooting season (yes I know people are still shooting in AZ, but for the rest of us it's f'n freezing and there are deer to be shot)

Is it really worthwhile to search out long barrel slow powder combinations for a bit more MV, or are you really wasting your time? At least with a 308 in F-TR, no matter what you do you probably can't reach the next node above the one that you can get to with a 30" tube, now maybe running a 32 you can get to the sweet spot with a little less powder and a little better brass life, but are you going to be able to get to something that pays a performance dividend in the wind? I am beginning to think not so much.

Case in point, for me. This yr I've experimented with a barrel up to 34" long at one point. Shooting 185s you really run out of powder before you get to the end of that. At one point I chronoed side by side same load, same bullet, chambers cut with the same reamer, and running 44.5gr of Varget the 34" was 40FPS slower than my 30" (both Krieger 1:10s). Even at 32" running slower powders I am able to achieve MVs in the mid 2800s with the 185s, but I'm finding that the accuracy is inconsistent. Looking back it seems that the load may be running right at the top of the node, and if the temperature got up the velocity seemed to get into a scatter node and my scores fell to pieces. (assuming the whole node theory is accurate)

Everything I've seen, read and heard says that with the 185 Bergers that the magic number is in the mid 2700s to maybe the low 2800s but you probably need to stop there. I'm not sure where the next node might be, but if it's up in the 2900FPS range then I don't see getting there with a load that is a) safe, b) allows use of brass more than once.

I've experimented with some other bullets, but not enough to put up any thoughts with data to back it up. Is there anything to this idea or am I missing something?

Has anyone got any experience with the 185s or other bullets one way or the other?

 

[Dos XX]

I did some limited testing this year with 185 Juggernauts. I was running them at 2815, based on drops at distance, and even a little faster for a while. When I got a chrono, I loaded up a series of increasing powder charges to verify velocities. I was right on with my drop based velocity of 2815, but I found the velocity was more consistent at 2750 than it was at 2815 and higher. The accuracy was better as well. When I got much over 2750, I could go up in powder charge and at some charge weights get less velocity than the .2 grain charge immediately below it. They ES was much higher over 2800 fps as well.

I used a ballistic calculator and determined that 2750 should get me to 1000 yds in any environmental condition I am likely to shoot in. This load has shot well for me at 600 yds. I have not been able to test it at 1000 yds yet. There is a local 1000 yd match in January. Hoping to test it then.

 

[CaptainMal]

Nothing to add except more "thoughts".

If you use a tuner my take is there is no node testing that can be done.

 

[Down South]

I used to run 2000 MR powder with 185s and 200s in a 28 inch 11 twist barrel. 2825 ftps give or take was easy to achieve with 185s without dangerous pressure, with a 32-34 inch who knows? With that being said, you give up the stability of Varget, not that 2000 MR is really bad but its not as good. My current rifle/barrel is a 10 twist 30 inch Brux and im running Varget at the 2750 node and my scores are actually better. The load holds really good vertical and is very accurate so to be honest the speed i lost isn't even a factor as it isn't gonna amount to that much wind drift anyway. I quit chasing the fastest/hottest loads and my brass last a much longer time now also.

 

[savagedasher]

Have you Used Norma 203B QL says 2734 at 57000 psi Larry

 

[XTR]

I used to run 2000 MR powder with 185s and 200s in a 28 inch 11 twist barrel. 2825 ftps give or take was easy to achieve with 185s without dangerous pressure, with a 32-34 inch who knows? With that being said, you give up the stability of Varget, not that 2000 MR is really bad but its not as good. My current rifle/barrel is a 10 twist 30 inch Brux and im running Varget at the 2750 node and my scores are actually better. The load holds really good vertical and is very accurate so to be honest the speed i lost isn't even a factor as it isn't gonna amount to that much wind drift anyway. I quit chasing the fastest/hottest loads and my brass last a much longer time now also.

Jade, I think if you are not running at the ragged edge the powder sensitivity is less of an issue, but if you are then you get into problems when the temp gets significantly hotter than your load was developed. If you were running say that same 2000MR at 2775 and the temp went up and it was running 2800 who cares, but if you were running at the very top of the node at 2835 and the temp went up and you found yourself at 2860 you may be all over the place or you may be blowing primers (or both ) The question really isn't about how fast can you push them, but can you push them fast enough to get to another node, and if not then the question isn't really what load but are there sweet spots that we F-TR shooters can get to with a 30-32 inch barrel and [insert any powder] that you just can't get beyond that. With the 185 the highest node we seem to be able to hit is the mid to upper 2700s. Has anyone seen that with any other bullets?

[edit] I don't know what voodoo causes the node, but everyone shooting seems agree that they exist and we try to find them, and whether it is certain pressure plateaus that the powder(s) gets uniform combustion or the barrel harmonic is at a certain point or that the bullet just finds karma they seem to happen. They also seem to happen about every couple of grains over the load size that we guys shooting cases roughly equivalent to the 308, and there is lies the real point of all this. If the nodes are at about every 1.5 or so grains, then if you are in a node at 2750, can you get to the next node that is at the equivalent of 1.5 grains more of the powder you are shooing, and I think the answer is no. As to Tuners, they may tune any load, but how wide is the band?

 

[savagedasher]

44.6 give you 2822 with a 34'' at 57900 psi

 

[Dos XX]

I didn't say in my post, but I am running PP2000MR. When I got my rifle, Varget was impossible to find. I worked up the 2000MR and it worked well for me, so I bought 8 lb jugs of the same lot.

I have some Varget now in 1 lb jugs though they are in several different lots. I may play with it if I get some time this year, but the 2000MR doesn't have me looking for another powder at this point.

Savage Dasher,
Does QL have PP2000MR in it?

 

[savagedasher]

Sorry it does not. Wow you guys lean on them the same pressure as you are using N230B is 50' faster then varget. Larry