Does Positive Compensation exist @ 600yrds?

[308win]

Positive compensation is questionable at best.
If you believe it exists it has to exist at every range.

I have to agree. Maybe my question should be....is it identifiable at 600? I've already shot the 100 yard ladder and picked a charge from it. Also did a seating test and have it down around .5moa. Hopefully get out later this week to see if it shows any promise? I cannot find either the picture or the target itself to show where I came up with the charge I'm using? I might have thrown it out with the trash, but that doesn't explain why I don't have a picture?

 

[308win]

Those projected velocities make a lot more sense now.

You know...you can rechamber that .260 Rem into a .260AI and pick up some added speed.
In my 20" .260AI, I am running a 140 Hyb @ 2914fps. I hit 3000fps where I finally hit some slight pressure. I bet that 16.5" should make 2750-2800+.

No doubt, it will be AI when I rebarrel it. I bought the rifle off one of my hunters that was sick and needed the money. It's supposed to have a 8.5 twist Shilen barrel, but I don't know? **** thing has always been supper picky about what it eats. I've run the gauntlet of bullets through it to end up with the 123 ELD-M. Shoots great with that bullet, just not enough juice for most of the pigs I encounter. So I thought I'd go 130 OTM? I've never had a barrel/bullet combo I couldn't get to shoot at least under MOA, but it flat refused to eat in those! Had a bunch of 135s sitting around so why not? Seems to be ok with them so far, but will let the target tell in a couple days? In all honesty, I put way too much effort into this setup, especially since it's my pickup gun. I figure if it's gonna be there, it might as well be capable out to at least the bullets lethal range?

 

[308win]

Just read this. Seems tuning a barrel is possible.

Using barrel vibrations to tune a barrel

A quick glance and that looks like I'll need a soft spot to sit and an adult beverage for the read? Thank you sir for the information

 

[Taylorbok]

is it identifiable at 600

if I was testing for positive compensation I would be loading ammo that has a 150-200 fps difference that should give you roughly .5 mil vertical at 600 if it's not compensating, should be plenty visible IMO

 

[Beluebow]

I believe in positive compensation and have seen it at 600 and 1000yrds many times. IMO PC only works at the distance its shot at.

This is a ladder shot in a round robin fashion at 600yrd with a 300wsm and 215 Hybrids....61.7-62.3 velocities cover 2887-2922.

 

[RockyMtnMT]

No doubt, it will be AI when I rebarrel it. I bought the rifle off one of my hunters that was sick and needed the money. It's supposed to have a 8.5 twist Shilen barrel, but I don't know? **** thing has always been supper picky about what it eats. I've run the gauntlet of bullets through it to end up with the 123 ELD-M. Shoots great with that bullet, just not enough juice for most of the pigs I encounter. So I thought I'd go 130 OTM? I've never had a barrel/bullet combo I couldn't get to shoot at least under MOA, but it flat refused to eat in those! Had a bunch of 135s sitting around so why not? Seems to be ok with them so far, but will let the target tell in a couple days? In all honesty, I put way too much effort into this setup, especially since it's my pickup gun. I figure if it's gonna be there, it might as well be capable out to at least the bullets lethal range?

Maybe a dumb question but have you cleaned all the copper out of the barrel from previous bullets before trying a different bullet? Different coppers sometimes don't play well together.

 

[RockyMtnMT]

I believe in positive compensation and have seen it at 600 and 1000yrds many times. IMO PC only works at the distance its shot at.

This is a ladder shot in a round robin fashion at 600yrd with a 300wsm and 215 Hybrids....61.7-62.3 velocities cover 2887-2922.

View attachment 564450

Are you finding positive compensation through finding a velocity node? That article that I found seems to indicate that it could be done with a barrel weight and some very sophisticated equipment to locate the point where ES and barrel harmonics line up so that the bullet exits the barrel at the same position/ location of vibration through the range of variation in velocity.

 

[308win]

Maybe a dumb question but have you cleaned all the copper out of the barrel from previous bullets before trying a different bullet? Different coppers sometimes don't play well together.

When I first got the rifle, no I was not. Since I cut it down and running a suppressor I have to clean about every 30 shots. I sure like being able to throw it out the window for a quick shot, but sometimes I think the cans can be a headache?

 

[Beluebow]

Are you finding positive compensation through finding a velocity node? That article that I found seems to indicate that it could be done with a barrel weight and some very sophisticated equipment to locate the point where ES and barrel harmonics line up so that the bullet exits the barrel at the same position/ location of vibration through the range of variation in velocity.

I haven't noticed a specific velocity correlation, not saying that there isn't one. It seems to be more harmonics based than velocity. Typically these overlapping areas shoot very very well.

 

[RockyMtnMT]

I haven't noticed a specific velocity correlation, not saying that there isn't one. It seems to be more harmonics based than velocity. Typically these overlapping areas shoot very very well.

Sorry to ask so many questions but how do you find the "sweet" spot? This thread is the first time I had ever heard the term positive compensation. I'm just trying to figure out how it is achieved.

 

[Beluebow]

Sorry to ask so many questions but how do you find the "sweet" spot? This thread is the first time I had ever heard the term positive compensation. I'm just trying to figure out how it is achieved.

Once you find the "node" you can break it down in tenths or just load in the middle and confirm....if I'm in a hurry I'll just load at the bottom of the node. Being at the bottom helps keep the velocity migration in check.

 

[Taylorbok]

Sorry to ask so many questions but how do you find the "sweet" spot? This thread is the first time I had ever heard the term positive compensation. I'm just trying to figure out how it is achieved.

The way I've heard people do it is shoot a ladder test at 100 yards and see where slower projectiles begin to climb on target. You want to be some where in the middle velocity of a few shots that climb on target.

 

[308win]

I haven't noticed a specific velocity correlation, not saying that there isn't one. It seems to be more harmonics based than velocity. Typically these overlapping areas shoot very very well.

With my very rudimentary knowledge of the subject and after reading the article RockyMtnMT posted, I've come to the conclusion that is what I'm searching for.....the overlap. When I first started the process, I was unaware it would only work at a given distance? In hindsight, that makes sense and won't be practical for what I'm doing. Just for curiosity sake, I'm still going to run a Ladder on either side of the charge I picked for positive compensation and see what that gives me? To be honest, I think I'm in over my head, but that's the only way to learn for me? My reading comprehension is terrible (never was a good student), I'm more of a "beat it to death" until I learn it guy Hoping to get out tomorrow to shoot, but life keeps getting in the way. I hope some of that much needed Texas rain does too? Building a 338EDGE right now (waiting for Shawn to call any day now) to stretch out to 2 miles. Might try the positive compensation method on that?

 

[RockyMtnMT]

Once you find the "node" you can break it down in tenths or just load in the middle and confirm....if I'm in a hurry I'll just load at the bottom of the node. Being at the bottom helps keep the velocity migration in check.

Is that the same as the optimum charge weight method?