Possible for two accuracy nodes for a barrel?

[Fiveohmike]

Hey Guys,

Just wondering about something. So when I went testing some handloads (H4895 Powder, CCI primers, 180g SMK) I found two velocities that produces 1/3ish MOA out of my AR10 build. I was testing 40g to 42.5g in .5g increments.

What I found is that the rifle LOVED 40.5 and 42g loads, but the shots spread out at the other ones. Is this hitting two barrel nodes?

Mike

[rsrocket1]

Very possible. Take a look at this:

http://www.desertsharpshooters.com/manuals/incredload.pdf

Take a look at the combined graphs on and following P.10.

[Ahhnother8]

YEP!

[Fiveohmike]

Sweet! Great info...I love this place haha

On a side note, some guy at the range was talking to me about how AR style rifles cannot be very accurate, blah blah. He saw my groups and promptly shut up lol

[10fcp]

http://optimalchargeweight.embarqspace.com/#/ocw-instructions/4529817134

Yep, there's a high node and a low node. Lots of good info on Practical riflery forum too.

[BigBronco]

Rsrocket1, Thanks for that link. Just too tired at 11:00 pm to digest it all. I got to page 7.Great info.

[wooger]

What were your velocities at those two weights?

[Fiveohmike]

What were your velocities at those two weights?

Sadly I do not know yet. I am awaiting my Chrono that will be here next week.

[GeoffLinder]

You can always find more than one barrel node (when testing a specific powder), might even find more than two or three if you look hard enough and run the velocity ladder far enough.

Always use a chrono as the velocity of a node is what you need to know, not the charge weight.

[choprzrul]

Then you have to consider different profiles from different powders. A faster burning powder like H4198 will accelerate the projectile in the barrel faster than a slower burning powder like Winchester 760 that will probably still be accelerating the bullet at the end of the barrel. This will all effect barrel resonance.

Think of this as a journey rather than an end point. Granted, the end point is to find the most accurate load that does the intended job the best. If 100yd accuracy is your endpoint, then I would think that 1/3" groups would be satisfactory and use the load that requires the least amount of powder. If, however, you are intending upon taking 500-600 yd shots across canyons, then you are going to want to find a load that yields the best down range performance at a given range.

Or maybe you are planning on doing 1000yd competitions. Then you might consider finding the particular bullet that is recommended by people who have already travelled this path. Each bullet/powder type is going to have different charge weights/velocities that it likes and dislikes. The journey you take to find those 'sweet spots' if the fun part.

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