anyone notice difference in poi in relation to cleaning

[Zen Archery]

Your supposed to clean your rifle?!

Yep. My .308 low 1" Right 3/4" starting @ 100 yards.

But I only clean after about every 200 rounds.

 

[Reynolds02]

I feel like I may have not been specific enough for some guys to know what I meant, what I have in question was the point of impact changing by .75 moa at 900 yards. I was interested to see when guys are seeing a change, whether it be 25, 50, 60, 80, 100, 200, 400 rounds down the tube. And how often guys are cleaning in regard to that. I understand barrels are different but I don't shoot competition(but not saying I'm not interested) and don't have a large group of friends who have custom rigs to hear what everybody is getting. I am really happy to get some of the information from this thread, but just wanted to make sure I got the right message across that I'm not questioning clean vs. Fouled. Just how many rounds are shooting to see a different poi or if they are not seeing it at all until accuracy falls off and how often you guys are cleaning. Thank you everyone for the information and extra tips

 

[Mikecr]

how many rounds are shooting to see a different poi or if they are not seeing it at all until accuracy falls off

Intended POI -vs- Actual POI , and accuracy, are the same thing.
Do you mean how many rounds until GROUPING falls apart?

 

[Reynolds02]

Intended POI -vs- Actual POI , and accuracy, are the same thing.
Do you mean how many rounds until GROUPING falls apart?

Lol I guess you haven't read all of the posts...I validated trajectory out to 900 with a new load getting less than an 1.5 inches of vertical shooting to the west with 7 mph wind and 60 rnds down the tube, cleaned the rifle, went to same location within the week and with around 15 rnds down the tube shot a Woodchuck at 925 with an extra.75 moa of elevation above what was called for, same wind direction but down to 3 mph...I have noticed a poi change in rifles before at a different round count in relation to cleaning depending on the rifle. My question is if and/or when are guys seeing a poi change in relation to last cleaning and what are rnds between cleaning...I disagree with your statement if I understood it correctly accuracy is how well your rifle shoots, poa vs. Poi is how much human error is involved gun)gun)

 

[Reynolds02]

Hey guys, I guess I am really confused, there has been several posts and now there are none, did I say something to upset or is there something completely stupid I have done or am I on the right path from what others have been doing??? I am to see what others have experienced and bring that together with what I have seen. Thanks, Tyler

 

[Mikecr]

'How well' a rifle shoots can be a deep and difficult consideration.

You validated trajectory at 900 one day, sounds like this was with multiple shots.
Another day you shoot at a GH at 925yds, sounds like you took multiple shots.
Now how are we to conclude every potential change here leads to barrel cleaning/fouling?
Could be ranging, slope, scope, bipod seating surface, mirage, air density, a blade of grass, etc..

Maybe if in follow-up under those conditions you had repeated the 900yd testing and validated .75moa change in trajectory, and determined that cleaning was the only physical change, we could then wonder if your fouling caused the .75moa of change.
Otherwise, it sounds like you just missed a GH at 925yds. Maybe you should move in closer until figuring it out.

You don't have to shoot very far to see a barrel fouling out. 200yds with repeatable conditions will tell you the answer better -than around 900yds. Right?

 

[Reynolds02]

Thanks for the info, I see what you are saying and agree more validation is needed to find the answer but I think it's going to be one of two things either mirage or poi change, you really got me thinking about the mirage, there was a good amount of mirage both days and with the wind being half the second day. I feel very good about the other aspects like accurate conditions, bipod, rifle, angle, scope...what has your experiences with mirage showed you?

 

[Reynolds02]

http://www.longrangehunting.com/forums/f17/shooting-mirage-54714/index3.html


I'm starting to really believe that this is the issue and Broz is probably going to have the post I feel really fits the situation I was having he said he will dial up 1/2 moa for effects when mirage is a known for cold borelightbulblightbulb...time will tell, I really appreciate what everyone has said because I will have more to take away from this thread than just the mirage...a detailed notebook will be so important going forward

 

[ForgivenAll]

Any possibility you were experiencing the effects of crosswind jump? The following is taken from David Tubb:

Crosswind Jump (CJ) — Gyroscopic and aerodynamic effects together cause a right-hand spinning bullet to strike higher in a right crosswind and lower in a left crosswind; the higher the wind velocity the larger the CJ. A ten mph crosswind at 200 yards will give an impact shift of 3/8 moa, which is 0.75
inches change of the point of impact. Increase wind velocity to 20 mph and the CJ increases to 3/4 moa, which is an impact point change of 1.5 inches. Thus, the wind drift hold points are high on the left and low on the right resulting in a tilted or angulated array.
(References: Harold Vaughn "Accuracy Facts," and McCoy "Applied Ballistics," plus our own tests.)

 

[Kansaswoodguy]

I have a 223 that takes around 30-40 rounds after cleaning to get fouled enough to close the groups back up to .75moa as a rule I no longer clean barrels of copper unless accuracy takes a dive