Concentricity Question

[dmoon]

@ 600 yards is where I'd like to stretch this rifle to, but the inconsistencies I'm having at 200 yards is putting a halt to that....for now. Gonna look into Concentricity and, upon recommendation by Dr. Vette, cartridge headspace. My head is spinning....but I feel like I've got avenues to look into now instead of "groping around in the dark".

You'll get it, most likely you'll laugh when you figure it out. Don't forget to try another powder too. Good luck!

 

[Deputy819]

You'll get it, most likely you'll laugh when you figure it out. Don't forget to try another powder too. Good luck!

Gotcha! Bought RL 22 to try also. Have been through IMR 7828 ssc, IMR 4831, H4831SC, and RL 19. Best numbers AND best groups have been with the new Enduron 4451 and BR2 primers....just not consistently.

 

[Dr. Vette]

....just not consistently.

Again, one might suggest it's because your reloading is not consistent either.

I use the Willis digital headspace gauge, but other companies make them as well. Look at a few, read some reviews, and go from there.

Clean them, anneal them, body size and then use the collet die. I think that you'll see improvements.

 

[Deputy819]

Again, one might suggest it's because your reloading is not consistent either.

I use the Willis digital headspace gauge, but other companies make them as well. Look at a few, read some reviews, and go from there.

Clean them, anneal them, body size and then use the collet die. I think that you'll see improvements.

Very true. While I've done the best I can with the tools that I currently have it sounds like there are areas of handloading that I've over looked which could make a definite improvement. Looks like I'll need a couple more "tools" on my reloading bench to work with Speaking of which I just looked at/read about the Willis digital headspace gauge and I really like what I just saw. Thanks for your advice. NONE of the information I've received here has fallen on deaf ears!!

 

[MagnumManiac]

Interesting. Will barrel harmonics play as important of a role in a 1" diameter barrel as it does a sporter Barrel? Another thing I've noticed about this rifle (besides it's inconsistencies) is that when it does turn out good groups they tend to be at a certain velocity and about 100-120 FPS apart. Would that be indicative of a good "harmonic node" or "velocity node"? Furthermore, will low ES and SD numbers relate with that node or does that have more to do with proper powder/primer combination?

Yes, even a heavy barrel oscillates as a bullet travels down it. The heavier the barrel walls the less the muzzle moves, but they ALL move.
Accuracy only occurs when ALL the bullets exit the barrel at the same point in the oscillation. If this occurs 100-120fps apart, then that is where the barrel is still or in the middle of it's swing. At 100yrds, this may give 1/4MoA groups, but shoot this same load at 600yrd or beyond, the vertical stringing will blow out the group.

True, most nodes do group together at a certain velocity, and you can 'track' that grouping quite reliably, BUT there are nodes that are quite narrow which are unsuitable for long range due to atmospheric differences influencing velocity that cause vertical.
This is why ladder testing at 300-600yrd is important, you want nodes that are wide and forgiving with slight powder or atmospheric conditions. Some powders are better at this than others, such as H4350 in Creedmoor/6.5x47 size cases, H1000 in 308/AI size cases.
I look for nodes that run .5-1gr wide where it makes no group size difference.
This is normally from powders that are on the slow side for the expansion ratio, the lower presssure helps 'soften' the load some while maintaining high/higher velocity than traditional powders.
The heavier the bullet, the slower the powder tends to be that is optimum for accuracy.

Hope this helps you understand this a little more.

Cheers.

 

[Deputy819]

Yes, even a heavy barrel oscillates as a bullet travels down it. The heavier the barrel walls the less the muzzle moves, but they ALL move.
Accuracy only occurs when ALL the bullets exit the barrel at the same point in the oscillation. If this occurs 100-120fps apart, then that is where the barrel is still or in the middle of it's swing. At 100yrds, this may give 1/4MoA groups, but shoot this same load at 600yrd or beyond, the vertical stringing will blow out the group.

True, most nodes do group together at a certain velocity, and you can 'track' that grouping quite reliably, BUT there are nodes that are quite narrow which are unsuitable for long range due to atmospheric differences influencing velocity that cause vertical.
This is why ladder testing at 300-600yrd is important, you want nodes that are wide and forgiving with slight powder or atmospheric conditions. Some powders are better at this than others, such as H4350 in Creedmoor/6.5x47 size cases, H1000 in 308/AI size cases.
I look for nodes that run .5-1gr wide where it makes no group size difference.
This is normally from powders that are on the slow side for the expansion ratio, the lower presssure helps 'soften' the load some while maintaining high/higher velocity than traditional powders.
The heavier the bullet, the slower the powder tends to be that is optimum for accuracy.

Hope this helps you understand this a little more.

Cheers.

Man, that explanation was dang near poetic! Understand completely. Did you happen to take a look at the OCW test picture I posted in this thread? With that particular powder, bullet and primer combination at 200 yards (arbitrary, same seating depth for all rounds) there was hardly any change in vertical P.O.I from 44.6 to 45.5 grains. Would that be an example of a "wide node" that you look for?

 

[MagnumManiac]

Man, that explanation was dang near poetic! Understand completely. Did you happen to take a look at the OCW test picture I posted in this thread? With that particular powder, bullet and primer combination at 200 yards (arbitrary, same seating depth for all rounds) there was hardly any change in vertical P.O.I from 44.6 to 45.5 grains. Would that be an example of a "wide node" that you look for?

Yes, that is the type of node I look for, but only if it groups without any vertical.
I used to play with QL, it has a feature known as Optimum Barrel Time. This is helpful SOMETIMES in getting close to a node without using lots of components as once you get that velocity you just do a few groups above/below in .3gr increments and fine tune.
OCW is very similar to ladder testing in a sense, I trust my ladder test results, they tell me a lot about the powder. I also use a Pressure Trace II, I no longer bother with QL.
I also run neck tension with lubed necks. This has given me single digit SD numbers and improved my scores more than any other thing I do. I have tried everything by elimination, this has been the ONLY thing that I could see make an impact at 1000mtr, MoA was terrible with unlubed necks and many fliers. Even NOT turning my necks didn't cause fliers, it did open MoA slightly, but not a deal breaker.
I still skim turn my necks, not for clearance, I have moved away from tight neck clearances, just so that they are uniform. I also use Forster FL Dies, somenhave bushings but I still use an expander that is .0005" larger than the bushing lubed with graphite.
As I said earlier, a loose, but not overly, case self aligns if you have the bullet just kissing the rifling. Although not all of my barrels like this and yet they still shoot around 3/8MoA which is about all I can get at 1000mtrs, no matter what I do.
Bullet jump is a not a dealer breaker either.

Cheers.

 

[Deputy819]

Yes, that is the type of node I look for, but only if it groups without any vertical.
I used to play with QL, it has a feature known as Optimum Barrel Time. This is helpful SOMETIMES in getting close to a node without using lots of components as once you get that velocity you just do a few groups above/below in .3gr increments and fine tune.
OCW is very similar to ladder testing in a sense, I trust my ladder test results, they tell me a lot about the powder. I also use a Pressure Trace II, I no longer bother with QL.
I also run neck tension with lubed necks. This has given me single digit SD numbers and improved my scores more than any other thing I do. I have tried everything by elimination, this has been the ONLY thing that I could see make an impact at 1000mtr, MoA was terrible with unlubed necks and many fliers. Even NOT turning my necks didn't cause fliers, it did open MoA slightly, but not a deal breaker.
I still skim turn my necks, not for clearance, I have moved away from tight neck clearances, just so that they are uniform. I also use Forster FL Dies, somenhave bushings but I still use an expander that is .0005" larger than the bushing lubed with graphite.
As I said earlier, a loose, but not overly, case self aligns if you have the bullet just kissing the rifling. Although not all of my barrels like this and yet they still shoot around 3/8MoA which is about all I can get at 1000mtrs, no matter what I do.
Bullet jump is a not a dealer breaker either.

Cheers.

Interesting. I use mica powder inside my necks which are consistently turning out .003 neck tension. Ordered a custom mandrel for the Collet Die just because the Smith who built this rifle recommended .003 neck tension. Thanks again for all the great information!

 

[Deputy819]

Again, one might suggest it's because your reloading is not consistent either.

I use the Willis digital headspace gauge, but other companies make them as well. Look at a few, read some reviews, and go from there.

Clean them, anneal them, body size and then use the collet die. I think that you'll see improvements.

Willis Digital Headspace Gauge purchased this morning. Can't wait to use it. Thanks!

 

[Deputy819]

If any of you guys are still watching this thread my Forster Case Inspector arrived today. I set it up per instructions and went to work. I didn't have any fired/unsized brass to check chamber concentricity, but I did check sized brass and loaded ammo concentricity at all three critical areas recommended. The worst I saw was just close to, but not quite at .002 runout and 1 actually had zero runout. So, I don't think my INCONSISTENT accuracy issues are concentricity related...concerning the ammo I'm cranking out anyways....

 

[oldno7]

There are some barrels that cannot be made accurate on a consistent basis.
I had a Rem. 700 in 300Roy, somedays I could get down to 3/4 moa, next time with same loads, same temps,wind, etc--1 1/2-2" groups. New barrel and it shoots lights out.
One can spend a lot of time and money chasing the impossible.

 

[Deputy819]

There are some barrels that cannot be made accurate on a consistent basis.
I had a Rem. 700 in 300Roy, somedays I could get down to 3/4 moa, next time with same loads, same temps,wind, etc--1 1/2-2" groups. New barrel and it shoots lights out.
One can spend a lot of time and money chasing the impossible.

Well, that's what I'm seeing....so far. While it's always kind of fun to add new "toys" to the bench it seems pointless if it's determined that the rifle itself is to blame.....and a NEW Douglas barrel at that! On the other hand.....I am learning A LOT!

 

[dmoon]

Most inconsistencies are human induced. There isn't a gauge to measure cheek weld pressure, hand or shoulder tension on the stock, or follow through on the shot. Usually if I throw one while shooting with my uncle he calls the "miss" as I shoot.....If you don't have an uncle like mine, set up a camera at the bench and watch yourself. You'd be amazed at your own inconsistency, usually from day to day more than shot to shot. But it doesn't take much of a difference from you at the bench to turn a 1/2 MOA rifle to a 1 MOA rifle.

 

[Deputy819]

Most inconsistencies are human induced. There isn't a gauge to measure cheek weld pressure, hand or shoulder tension on the stock, or follow through on the shot. Usually if I throw one while shooting with my uncle he calls the "miss" as I shoot.....If you don't have an uncle like mine, set up a camera at the bench and watch yourself. You'd be amazed at your own inconsistency, usually from day to day more than shot to shot. But it doesn't take much of a difference from you at the bench to turn a 1/2 MOA rifle to a 1 MOA rifle.

I watched a video the other day that demonstrated that VERY thing. The guy was showing how to properly get consistent cheek weld by concentrating on consistent stock contact at a particular place on your jawbone and then "rolling" (if you will) your face downward for proper scope/eye orientation. He also demonstrated the art of attaining firm, but NOT forward shoulder contact against the butt-stock and a few other little goodies. Too bad there's NOT gauges for that stuff.