node help

[Dwh7271]

SS,
As an addition with the powder you are using you cannot get to Node 4 which is 1.101. You would probably need to get up around 67000 pressure to hit that node which as you know is dangerous ground.

 

[Silentstalker]

Thank you both! The overall length from end to tip is 3.333" does that change anything?

 

[Dwh7271]

Not a lot but a little.
Puts you here.

+00.0 102 57.01 2882 2767 57252 11580 97.6 1.200 ! Near Maximum !

 

[Silentstalker]

I am trying to wrap my head around this thread. I am wondering if someone could tell me more about my rifle/load?

.270 Win.
24" barrel
Win brass
Win primer
150 gr. BT
57 gr. of H4831
Average water capacity of 6 fired cases is 70.78 (pic attached to see if I did it correctly)
My average velocity over a chrony is 2875 fps.

What is your cases OAL?

If you havent already, take a read through Chris Long's site. http://www.the-long-family.com/optimal barrel time.htm

and take a look at the "nodes": http://www.the-long-family.com/OBT Table.pdf

I take a paper towel and try to remove as much of that convex meniscus of the water. I think its more accurate because you are not guessing if one case has more water (higher menuscus) than another case. If you weigh them with a leveled amount of water, your case capacity will go down, and your loads/ nodes below will be different.

For your rifle and load, I bolded the barrel times that land close to or on a node.
24" barrel nodes: 0.8160 0.8948 1.0221 1.1016 1.2282 1.3084 1.4343

Cartridge : .270 Win. (SAAMI)
Bullet : .277, 150, Nosler BalTip 27150
Useable Case Capaci: 62.569 grain H2O = 4.063 cm³
Cartridge O.A.L. L6: 3.340 inch = 84.84 mm
Barrel Length : 24.0 inch = 609.6 mm
Powder : Hodgdon H4831 ?

Predicted data by increasing and decreasing the given charge,
incremented in steps of 1.0% of nominal charge.
CAUTION: Figures exceed maximum and minimum recommended loads !

Step Fill. Charge Vel. Energy Pmax Pmuz Prop.Burnt B_Time
% % Grains fps ft.lbs psi psi % ms

-10.0 92 51.30 2581 2219 40979 10390 93.2 1.401
-09.0 93 51.87 2611 2270 42328 10524 93.7 1.380
-08.0 94 52.44 2640 2322 43722 10655 94.2 1.359
-07.0 95 53.01 2670 2374 45166 10783 94.7 1.338
-06.0 96 53.58 2699 2426 46658 10908 95.2 1.318
-05.0 97 54.15 2728 2479 48205 11030 95.6 1.298
-04.0 98 54.72 2758 2533 49805 11148 96.0 1.279
-03.0 99 55.29 2787 2588 51459 11263 96.4 1.260
-02.0 100 55.86 2817 2643 53180 11374 96.8 1.241
-01.0 101 56.43 2846 2698 54955 11482 97.2 1.222
+00.0 102 57.00 2876 2755 56786 11585 97.5 1.204 ! Near Maximum !
+01.0 103 57.57 2905 2811 58676 11685 97.8 1.186 ! Near Maximum !
+02.0 104 58.14 2935 2869 60631 11780 98.1 1.169 ! Near Maximum !
+03.0 105 58.71 2964 2927 62656 11871 98.4 1.152 ! Near Maximum !
+04.0 106 59.28 2994 2985 64754 11957 98.7 1.135 !DANGEROUS LOAD-DO NOT USE!
+05.0 107 59.85 3023 3044 66928 12039 98.9 1.118 !DANGEROUS LOAD-DO NOT USE!

Results caused by ± 5% powder lot-to-lot burning rate variation using nominal charge
Data for burning rate increased by 5% relative to nominal value:
+Ba 102 57.00 2950 2899 62185 11601 99.2 1.158 ! Near Maximum !
Data for burning rate decreased by 5% relative to nominal value:
-Ba 102 57.00 2791 2594 51429 11424 94.8 1.257

So, based on this info, would I be better to move down to 56.43 or am I close enough to the node to keep it where it is at? It shoots about 3/4 moa.

Also, my 150 PT load is 56.5 gr. with a slightly different coal. It shoots just moa also.

Thank you for your help!

 

[Dwh7271]

I'd stay put

 

[Wyo7200]

If you're happy with it, keep it as Dwh says.

My inner tinkerer (also known as the little devil on my shoulder) says no harm in loading a few at 56.4 and trying them to see if this modeled data truly resembles real world results.

 

[Silentstalker]

Sweet! Thanks again. Im sure I will continue to tinker but feel good as is, especially with this confirmation.

 

[Mikey338]

QL says this should be right on node 4 and its dramatically better. Going from around 1 inch groups working up the loads in .5 grain increases, then it just went through the same hole . Will chronograph it next time out as I didn't have time today. Tried some 105 Amax's but I didn't have enough powder to tighten the groups up, they started out at 4 inches and got down to 2 inches. Was being cautious and am probably 2-3 grains off where I need to be, aiming for node 5 will be interesting to see if it does the same thing again
Load safe in my rifle only work up

 

[Dwh7271]

Nice shooting and great target!

 

[DrMike]

Oh, yeah, targets such as that will put a smile on the face of the most jaded rifle crank. Fine riflery.

 

[Mikey338]

It's a pity I butchered the first shot of that loads 200 yard group pulled it way right, the next 2 landed .8 apart. Oh well next time.....

 

[Mikey338]

I'm absolutely amazed with these nodes it just incredible how predictable it's becoming my 105 Amax's at predicted node 5 dropped to a 0.3 inch group!!and just 1 inch lower than the 87 grain V-max which is fantastic, it wasn't looking good there for a while.
Now with confidence I can tackle my Ruger Hawkeye in 7 mm Rem mag which I'd given up reloading for it.
Thanks a lot guys

 

[Dwh7271]

Anytime Mikey.
If you get a chance, take a look at the sticky on QuickLoad Fotis put at the top of this forum. It gets into the more technical aspects of it and may help you go a little further.
Ridgerunner and Wyo have both been really doing good stuff in that thread.

 

[Mikey338]

What I'm doing with quick load is run 4 groups of different charge weights over the chronograph, adjust the Ba in the powder part of quick load (as per QL sticky)to match up with the averaged velocity of those groups. Then with the corrected Ba adjust the powder charge till it matches a safe node to my barrel length. Shoot to confirm accuracy and velocity "hey presto" tiny groups.

 

[Dwh7271]

That's pretty much what I'vd been doing lately also.
You can get into adjusting weighting for overbores and stuff also. That makes a significant difference sometimes.
The most important part, as you already know, is finding the baseline for the lot of powder you have and the only way to do that is chrono enough loads to reach a reasonable number to work from.(works great when you don't shoot the chrono which I did recently again :lol: )