ES and positive compensation

[rhovee]

I have always been in the camp the ES and low SD are a huge deal when shooting long range. If your not below an SD of 10 you will be in trouble. What i have noticed is when i shot a ladder, some of the faster bullet impacts lower on the target. So if your barrel timing changed and your POI was lower with a faster speed, how much does ES really matter?

 

[dcali]

This is a giant can of worms, but I think it suffices to say that it matters to the extent that it impacts where your bullets hit. A very large ES isn't going to work ever. A small one is much more nuanced.

 

[Alex Wheeler]

I have always been in the camp the ES and low SD are a huge deal when shooting long range. If your not below an SD of 10 you will be in trouble. What i have noticed is when i shot a ladder, some of the faster bullet impacts lower on the target. So if your barrel timing changed and your POI was lower with a faster speed, how much does ES really matter?

Depends on how you tune. If you have to or prefer to tune at 100 you have no choice but to watch ES. Personally I prefer to tune with PC, so I do it at 1k and dont look at the es. I have seen 1.5" with 21 ft es at 1k. Most of the better groups are over 10 ft es almost as a rule. I have tried to find the pc point at shorter range and have got lucky a few times, but I cant do it consistently at all, so I am forced to use the 1k ladder. Since you are doing 600 yard ladders, I would ignore es if it is reasonable. Like under 25.

 

[rhovee]

I was figuring it pc has to come into play. Most things I have heard/read is you will get vertical with higher es. Even at 20-25 FPS. Or just running it through a drop chart. But I didn’t find this to be true at 600 because of pc. Just shows an experience is better than an opinion. I just need a rifle that doesn’t eat 86 grains of H1000 to figure this stuff out! Do the best loads usually show some pc?

 

[Bart B.]

It's been known for over a century that if the muzzle axis is on the upswing when bullets leave, slower ones can leave at higher angles than faster ones. The British SMLE 303's had good positive compensation for their big muzzle velocity spread. See link below:

https://archive.org/stream/philtrans05900167/05900167#page/n0/mode/2up

People have put moveable weights on barrels near the muzzle that tune the muzzle axis vertical vibration frequency to positively compensate for velocity spread. Browning's BOSS did that. Long range groups are smaller in MOA when tuned for but mid range ones are bigger. Tune for smallest midrange groups and those at long range will be bigger.

Good info:

http://www.geoffrey-kolbe.com/articles/rimfire_accuracy/tuning_a_barrel.htm

Tuner links in web site below are interesting:

http://www.varmintal.com

A related thread:

http://forum.accurateshooter.com/threads/positive-compensation.3890281/

 

[rhovee]

Man thats a long read. A lot of it was over my head. I heard you broke a record today. Thanks for taking the time to respond.

 

[Bart B.]

I heard you broke a record today.

I don't think So. Got rid of my old 78, 45 and 33 rpm vinyl ones last month.

 

[Dusty Stevens]

Man thats a long read. A lot of it was over my head. I heard you broke a record today. Thanks for taking the time to respond.

wrong bart