Gunsmithing MOA confusion

[ericf]

I read on this forum a lot. Don't post much, but attempt to "absorb" what I read. Sometimes it becomes confusing. For example.
I've read many posts that state that a certain rifle is capable of holding "X" MOA out to "Y" distance.
Now the confusing part is, If that rifle can hold "X' MOA at "Y" distance, shouldn't it hold that same MOA to any distance??? Of course I'm excluding factors of wind ,weather, shooter ability, or the bullet "petering" out. I'm examining the rifle only. And being realistic
If it will hold a .5 MOA at 100, it Should shoot .5 MOA at 600. Again, exclude bullet ballistics and weather. I'm only looking at the mechanics of the rifle.
Am I wrong in my asumption?

 

[doc76251]

Re: MOA confusion

No you are correct, however the exclusions you listed are rather significant. It would be more appropriate for a shooter to say "I" can hold 1/2 MOA out to 500 with this rifle. THAT is not nearly as common as the internets make it seem.

Cheers,

Doc

 

[ericf]

Re: MOA confusion

I thought that my logic was correct. I can not understand why the statement is made about rifle accuracy, ""It will hold "X" out to 300 yards"".
It makes the reader think that once past 350 yards, bad things begin to happen to the ballistics with the described rifle.
Thanks for clearing that up for me

 

[858]

Re: MOA confusion

Keep in mind that on the internet if you get a single 1/4" group out of 50 groups that means you have a 1/4" gun and you're a 1/4" shooter.

 

[ericf]

Re: MOA confusion

HUH??
Since weather conditions effect ballistics in a dramatic way, what is the effects on ballistics of shooting in/through rain or snow (flakes, not banks, and drops not lakes).

 

[dmgreene]

Re: MOA confusion

ericf alot of the time the rifle may be capable but the load may not be as good out at longer distances. I have seen some loads that would shoot very good groups at 100 yards but by the time they made it to 500 yards they were terrible. Problems with extreme velocity spreads take some distance to show up.

 

[x ring accuracy]

Re: MOA confusion

All I know is that with my new keyboard, ALL of my rifles are now sub MOA at 10,000 yds. Sorry, couldn't resist.

 

[doc76251]

Re: MOA confusion

ericf,

I believe 858 and keydiver are engaging in what is known as sarcastic humor, or maybe just regular humor depending on your crowd

dmg makes a valid point that some cartridges fall apart after a certain distance. You excluded all variables in your question which is why I didn't mention it, your original question has nothing to do with shooting but physics and math.

IMHE, The only thing I factor into shooting in the rain or snow is temp, and keeping the wet crap out of the action.

I am a proud alumni of the one and only Winter ASC Idiot Match. Yes, I froze a bolt, blew a primer, hydro dented a case and thought I would break the bolt handle off my rifle. All for leaving the action open for 5 seconds.

Cheers,

Doc

 

[LoneWolfUSMC]

Re: MOA confusion

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ericf</div><div class="ubbcode-body">HUH??
Since weather conditions effect ballistics in a dramatic way, what is the effects on ballistics of shooting in/through rain or snow (flakes, not banks, and drops not lakes).</div></div>

Shooting in the rain and snow affects the shooter far more than the bullet. The rifle can be effected, but that will depend on what environment it was designed to function in.

 

[Fritzcat]

Re: MOA confusion

Another question, How & why a load does not shoot good at 100yds, but tightens up after that to be consistant?

 

[BLAWTON]

Re: MOA confusion

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Fritzcat</div><div class="ubbcode-body"> Another question, How & why a load does not shoot good at 100yds, but tightens up after that to be consistant? </div></div>

From what I have seen and heard the thoery or term used is the bullet goes to sleep. They may be variances in the flight and stability of the bullet for the first few hundred yards depending on bullet and caliber.

 

[NBLongRanger]

Re: MOA confusion

on the original question your of course correct.

MOA is by sniper-definition 1" @ 100yrds.
Therefore .5MOA@100yards = 1/2" group on paper(FBI standard)

Now comes the context.
.5MOA @ 1000yards sounds like a tight group(and is) but it's 5" on paper...And also very very hard to get without some decent equipment.

The most common accuracy, I see, attained by decently trained recreational long-range shooters is sub-1.5moa@1000yards... Roughly, consistent center-mass hits..


And i agree with NotaGuru on the second. Shoot some .22sub-sonic and you'll see some interesting paper.

 

[LoneWolfUSMC]

Re: MOA confusion

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: NBLongRanger</div><div class="ubbcode-body">MOA is by sniper-definition 1" @ 100yrds.
Therefore .5MOA@100yards = 1/2" group on paper(FBI standard)</div></div>

Not sure what a "sniper-definition" is and how it differs from a regular definition, but what you are talking about is IPHY (inch per hundred yards) not MOA. Moa is 1.047" @ 100 yards.

I am also not sure what the FBI Standard you are quoting is.

It's true that most shooters just round MOA to IPHY, but that doesn't make it correct.

 

[Lindy]

Re: MOA confusion

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">The most common accuracy, I see, attained by decently trained recreational long-range shooters is sub-1.5moa@1000yards... Roughly, consistent center-mass hits..</div></div>

At a match this past weekend which drew 53 shooters from all over the country, the shooters made a cold-bore shot at a known-distance 1000 yard target sized 11.75 inches wide by 22 inches tall.

The hit percentage on the first shot was 13 percent.

 

[Downzero]

Re: MOA confusion

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Fritzcat</div><div class="ubbcode-body"> Another question, How & why a load does not shoot good at 100yds, but tightens up after that to be consistant? </div></div>

I think it mostly has to do with the shooter. Wind and gravity make a much bigger difference at distance than at close range. Having consistent ammo eliminates as much of that as possible, making it much easier for the shooter to put the rounds on target.

At distance, we all focus more than we do at 100 yards. Combine that with good ammo and that means better hits at distance than up close.

 

[wwood]

Re: MOA confusion

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Downzero</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Fritzcat</div><div class="ubbcode-body"> Another question, How & why a load does not shoot good at 100yds, but tightens up after that to be consistant? </div></div>

I think it mostly has to do with the shooter. Wind and gravity make a much bigger difference at distance than at close range. Having consistent ammo eliminates as much of that as possible, making it much easier for the shooter to put the rounds on target.

At distance, we all focus more than we do at 100 yards. Combine that with good ammo and that means better hits at distance than up close. </div></div>


So far that is the best explanation I've heard. I've never understood the physics behind a group of bullets being on divergent trajectories for the first 100 yards, then the outliers "remember" where the line of sight was and make a course correction to group tighter farther out.