Ladder test and nodes

[alton9]

So if I load the same caliber, same powder lot, primer lot and bullet lot, can I expect the nodes to be at the same charge weights in two different barrels?
And does barrel length have any effect on where the nodes are?
TIA, alton9

 

[rsmithsr50]

all gun are different. all bbl are different.
if the length is diff, the velocity is diff.
maybe but no promises

 

[rammac]

If absolutely everything were exactly the same (which is impossible), then theory says yes.

But since no two barrels, components, or shooting conditions can possibly be the same - maybe.

The idea of a really good load is that it will tolerate some variations in conditions and components and still average about the same group size. From my personal experience I can say that this is hard to find in real life, especially if you want high velocities. Slower velocity accuracy nodes are more tolerant of variations.

If the barrels are different lengths then most likely, no, they wont shoot the same. But like most things in life there are exceptions. If your barrels only differ by an inch or two then they might shoot the same but when your barrels are different by several inches or more they definitely wont shoot the same. I work with the M1A semi-auto quite a lot and I can tell you that more often than not the 18" (Scout barrel length) to 22" (standard barrel length) barrels will shoot most ammo to about the same precision (group size) but when you shoot the same ammo in the short 16" (SOCOM) there will be a very large difference. The shorter barrel will shoot just as accurately, maybe even slightly better, than the longer barrels if you compensate by using faster powders and/or lighter bullets.

 

[std7mag]

All barrels/firearms are different.
Even from the same manufacturer on the same day.
Different length barrels will have different nodes. As will thicker, thinner barrels.
All will have different harmonics.

To get the same node would way more likely by the fluke than the rule.

 

[Straightshooter1]

So if I load the same caliber, same powder lot, primer lot and bullet lot, can I expect the nodes to be at the same charge weights in two different barrels?

No.

And does barrel length have any effect on where the nodes are?

Yes

As other's have pointed out, barrels are different. . . even 2 barrels, supposedly the same from the same manufacturer, can be different enough for a node to be different, as barrels are cut to specs the tools wear and as they wear minute changes are taking place with each one finished. Then, of course you have barrels of the same length having different contours and/or chambers cut differently from one manufacturer to another, AND . . . you have custom barrels configured differently. So, you see . . . a lot of variables involved. However, if you have two barrels of the same specs made at the same time by the same tools, the node may not be exactly the same, but it likely would be very close if not.

 

[DirtySteve]

If you have a 24" M24 contour 308. Try 44.3 grs of Varget... If it shoots under a half inch. Then yes.. The nodes are the same. I believe the node for similar length and contour barrel will be close. If you are after Bench Rest accuracy then, No. I don't think they will be the same.

 

[Jennb]

I have had 6 Krieger barrels done 2 at time over a 3 yr period by the same gunsmith with the same reamer. Each set of barrels shot identical loads with no difference in powder charge or seating depth and velocity. Only difference was when I changed powder lots I had to adjust charge accordingly. I do all the necessary testing on both barrels to ensure any changes get made for optimal accuracy.

 

[Ned Ludd]

I'm with Jennb on this. Two barrels of identical finish length and contour can often tune in with loads that are pretty close, if not identical to where a previous barrel of the same length, contour, twist rate and groove pattern did. At a minimum, it would not be unreasonable to expect it to tune in fairly close to same node(s), particularly if you compare the loads in the two barrels when they had comparable round counts. Unfortunately, "pretty close" may not always cut it for many of us in terms of precision, so a full load work up is in order no matter how close the barrels may seem to be. There can sometimes be differences in what may otherwise appear to be identical barrels that will only show up when you shoot them.

For example, some barrels can be faster or slower with the exact same load. That doesn't mean you're necessarily hitting a "different" node, it simply means that a specific node is coincident with a slightly faster or slower velocity in one barrel as compared the other. In other words, it's probably not a "different node" unless the velocity is dramatically different for a given length barrel. So you do a complete load workup, and the barrel tunes in where it tunes in, regardless of length, contour, or how similar it is supposed to be to the previous barrel.

 

[500yards]

When I've done ladder tests at 250 yards a good vertical node is less than half and inch.

I'd expect considerably less than an inch at 330 yards but have no direct experience at that distance.

 

[JFrank]

So if I load the same caliber, same powder lot, primer lot and bullet lot, can I expect the nodes to be at the same charge weights in two different barrels?
And does barrel length have any effect on where the nodes are?
TIA, alton9

i would not expect two different barrels have the same node nor would I be shocked if they did.
J

 

[grovey]

I own / have owned three factory rifles that all shoot a certain load a 1/4" or less @ 100yds. The BTO # differs by 0.006-0.010 between the three, but if I set the bullet the same distance from the lands. Although all are the same make and caliber, they're three different bbl lengths, 2 are hvy bbl'd, and one of them is a sub 6 lb rifle bare.

I'm certainly not claiming every gun will like a load worked up in another rifle, or that one load will be safe in another rifle for that matter, but in my case it does. The load is moderate, and all three guns like it. To be fair... the newest gun may change it's mind when the bbl speeds up. I tested the load for shits and giggles during break in, and it went .230 with rds 8,9 and 10 out of the rifle shooting off my truck.

 

[dmoran]

@alton9
My primary pet loads more often then not, shoot very well in all my barrels/rifles that wear the same chamber. And with small amounts of refined tuning, are likely to do great in each barrel. While velocities might not be spot on between barrels, typically there in the same "ballpark".

 

[Coyotefurharvester]

A buddy and I had matching contour (rem sendero/varmint- mine is fluted) Lilja barrels chambered with the same Manson reamer. I told the smith that I wanted matching chamber/headspace so I could load for both. The rifles are coyote hunting rifles, the rifles both shoot reloads and a couple factory ammo types the same. I extremely happy with how they turned out. When I ordered the blanks, I let Lilja know about my "experiment".

 

[Clcustom1911]

@alton9
My primary pet loads more often then not, shoot very well in all my barrels/rifles that wear the same chamber. And with small amounts of refined tuning, are likely to be great in each barrel. While velocities might not be spot on between barrels, typically there in the same "ballpark".

This.

I've made 6.5 Creedmoor ammo that has shot well in 4 different rifles with 24" medium to heavy contour barrels. "Shot well" means 3/4 MOA or better out to 300 in all the rifles. 2 were custom barreled actions, 2 were factory. Velocities were different in each rifle and SD was anywhere between 3-10 and ES was between 5-30. Obviously the custom rifles shot a bit better

When you make your loads it depends on how wide your powder charge node is and if you're in the correct seating depth node/window as well. I use the widest node possible node so I dont have to weigh each charge to the granule. Hint: based on my experience, it's usually not the top velocity node for most powders.

To the OP: no the ammo wont shoot the exact same, but should be "good enough" or require minor tuning.

 

[DirtySteve]

This.

Hint: based on my experience, it's usually not the top velocity node for most powders..

This make sense because the faster speed would be a higher frequency in the vibrations induced during the firing process. Higher frequency would mean narrower nodes... Just my thinking. No proof on this..

 

[alton9]

Thanks for everyone's input. I had my own thoughts on the subject, and everyone's experience seem to confirm I was on the right track......... It's a definitive possible maybe.... LOL.....
Thanks all, alton9