How accurate is my rifle

[michaelmew]

I am always reading about guys' guns that are MOA or Sub MOA or 1/2 MOA or whatever. I thought I had a clear understanding, but I read something on the internet (so it must be true) that has me confused again.

1 MOA @100 yards is 1.047". So, 1 MOA (@100yds) is a group (3 shot) that will fit in a circle less than or equal to 1.047" or 1 3/64" in diameter. Correct?
1/2 MOA (@100yds) is a group (3 shot) that will fit in a circle less than or equal to 0.5235" or 67/128" in diameter. Correct?

1 MOA @ 200 yards is 2.094". Same logic as above. Correct?
1 MOA @ 300 yards is 3.141". Same logic as above. Correct?

And so on... BTW, just to be picky, is that a measurement from the center of the bullet impact or the edge?

I'd like to know how to be able to CORRECTLY identify my rifle's capabilities (and I assume some others would too). Do you guys all know this because of military training, or did your Grandpa explain it when he taught you how to shoot? Surely I'm not the only one who missed that portion of marksmanship 101.


-mm

[Whelenon]

Grandpa always told be moa is measured from center to center and I like to shoot 5-shot groups just because I think it give a better sense of repeatability. For me it's an exercise to determine my rifle's capabilities, how accurate and how precise.

[stokesrj]

Center to center is the proper way to measure, which is the same as outside edge to inside edge of widest shots. However three shot groups, although not meaningless are a poor indication of the rifles capabilities. MOA gus will occasionally shoot three shot groups in the .2 MOA range but that does not mean they are .2 MOA guns, if you shoot five groups of five shots and take the average then you have a meaningful measure of your guns capabilities for hunting and informal target work. For serious work I require my match rifles to group 20 shots in .5 MOA because it is typical to shoot 20 shot strings in the matches I participate in.
Bob

[LR1955]

I am always reading about guys' guns that are MOA or Sub MOA or 1/2 MOA or whatever. I thought I had a clear understanding, but I read something on the internet (so it must be true) that has me confused again.

1 MOA @100 yards is 1.047". So, 1 MOA (@100yds) is a group (3 shot) that will fit in a circle less than or equal to 1.047" or 1 3/64" in diameter. Correct?
1/2 MOA (@100yds) is a group (3 shot) that will fit in a circle less than or equal to 0.5235" or 67/128" in diameter. Correct?

1 MOA @ 200 yards is 2.094". Same logic as above. Correct?
1 MOA @ 300 yards is 3.141". Same logic as above. Correct?

And so on... BTW, just to be picky, is that a measurement from the center of the bullet impact or the edge?

I'd like to know how to be able to CORRECTLY identify my rifle's capabilities (and I assume some others would too). Do you guys all know this because of military training, or did your Grandpa explain it when he taught you how to shoot? Surely I'm not the only one who missed that portion of marksmanship 101.


-mm

Mike:

To correctly state your rifle's capabilities you would need a rifle vice anchored to a very solid concrete bench so the rifle would not move when it fired. You would pull the trigger mechanically and fire a string at what ever distance you are using. Then you would figure out the mean radius of the group by careful measurement. You would then communicate the accuracy in terms of mean radius.

Of course, no one but me would understand what you were trying to communicate so guys shoot groups at a specific distance, then determine what shot or shots they want to eliminate from the measurement, and measure the remainder of the shots. For example, if I am shooting for group and call a shot that was outside my standard of performance, and it went outside that standard, I would not include it in the measure because I called it out and it went out. I do not accept the notion of a 'flyer' so if a shot doesn't go to call and is out of my standard, it gets counted. The reason why I count these 'flyers' is because something went wrong that I can't determine so it is a mechanical issue and thus part of the group size.

Whether you go center to center, edge to edge and subtract one bullet diameter, is up to you but you may want to state how you measured when you state your group size.

I go with four each, five shot strings no matter how I present the data. And, I will not shoot for group at anything closer than 200 yards. And, I will state the range where I took the group size. A rifle / ammunition combination that holds one minute at 600 yards means more than the same rifle holding one minute at 200 yards.

So, unless you want to measure a mean radius, it is up to you. Just state your process.

LR1955

[jessegibson1978]

Probably not what you are looking for but MOA is minute of angle it's actually 1/60 th of 1 degree everyone just uses 1 inch for a base line however your numbers are correct.

[Drifter]

I enjoy shooting small groups as much as anyone, but as a hunter, I'm mostly concerned with where the very first cold-bore shot lands.

Some bullets from some barrels shoot admirably from a warm barrel, but miserably from a cold bore left fouled by the same load. Hunting bullets, especially bonded versions, seem more likely to throw the first shot. Match bullets seem less likely to suffer from this issue. It pays to test if cold-bore shots are what's important to your application.

[LRRPF52]

I subscribe to the "cold bore shooter" concept more than the cold bore rifle. Dry-firing helps eliminate this issue, as does shooting through a fouled, versus clean barrel.

During a military sniper instructor course some friends of mine were running, on the 2nd day, they took half the shooters and had them practice dry-firing for about 5 minutes, while the other half of the class did not. Guess which group had a bunch of "cold bore" fliers, and which one didn't?

I think a great topic has potentially emerged from this, in that the OP asked, "How accurate is my rifle?", when maybe we should be asking, "How accurate am I with my rifle on the first shot?", especially as most of us place a high importance on whether or not we can place that first shot within a certain predictable cone of error, whether it be .5 MOA as stokes' requires to be competitive, 1 MOA for me to make a hit on a 12" steel plate at 600yds with leeway in my windage estimation, or 2 MOA for the hunter drawing down on a buck at 245yds with leeway for windage estimation.

[Drifter]

I subscribe to the "cold bore shooter" concept more than the cold bore rifle.

I don't disagree with you, but can assure you that some bullets and / or barrels are more prone to cold-bore fliers than others. Take more than one rifle or upper to the range, practice with one, then switch to the other to test the theory while eliminating the "cold-bore shooter". Use some bonded hunting bullets with the bore left fouled from a previous trip with the same load.

[LR1955]

I enjoy shooting small groups as much as anyone, but as a hunter, I'm mostly concerned with where the very first cold-bore shot lands.

Some bullets from some barrels shoot admirably from a warm barrel, but miserably from a cold bore left fouled by the same load. Hunting bullets, especially bonded versions, seem more likely to throw the first shot. Match bullets seem less likely to suffer from this issue. It pays to test if cold-bore shots are what's important to your application.

Drifter:

To be up front, I view all the stuff about 'cold bore' zeros to be more myth than fact. I believe the majority of variance from a zero is due to the shooter firing his first shot of that day, with all the baggage he takes to that shot.

If the barrel sucks, it will suck dirty or clean no matter the bullet. If the bullet sucks, it won't get better because the barrel is dirty, hot, or cold. This is because bullets that suck are generally not balanced well and a dirty or warm barrel won't change how the bullet was made.

Also, I haven't seen any indication that such a thing exists with barrels or ammunition ranging from service through match grade. I have seen hundreds of pages of 'cold bore' shot records and haven't seen a pattern that anyone can predict.

Finally, one shot won't change barrel temperature enough to have any meaning and one shot won't put enough fowling down the barrel to change anything, either.

What heat, cold, or humidity may do is cause problems between a receiver and a wooden stock which in turn may cause zero problems.

LR55

[Drifter]

Drifter:

To be up front, I view all the stuff about 'cold bore' zeros to be more myth than fact. I believe the majority of variance from a zero is due to the shooter firing his first shot of that day, with all the baggage he takes to that shot.

If the barrel sucks, it will suck dirty or clean no matter the bullet. If the bullet sucks, it won't get better because the barrel is dirty, hot, or cold. This is because bullets that suck are generally not balanced well and a dirty or warm barrel won't change how the bullet was made.

Also, I haven't seen any indication that such a thing exists with barrels or ammunition ranging from service through match grade. I have seen hundreds of pages of 'cold bore' shot records and haven't seen a pattern that anyone can predict.

Finally, one shot won't change barrel temperature enough to have any meaning and one shot won't put enough fowling down the barrel to change anything, either.

What heat, cold, or humidity may do is cause problems between a receiver and a wooden stock which in turn may cause zero problems.

LR55

I use "cold-bore" as a general term, as I don't really think barrel heat is the culprit in my particular case. I think the issue lies mostly with copper fouling, where as bonded bullets seem noticeably worse regarding first-shot fliers from a barrel left fouled with the same bullet (which pertains to hunting applications).

I shoot almost every day with few exceptions. I've shot my entire life, but for the last couple of years, I probably average at least 4 days per week shooting, almost exclusively 6.5 AR's (Grendel and Creedmoor), with some 5.56 and 7.62x39 mixed in once in a while. When it's not hunting season, I might make 3 range trips in a day (600-yard private range 3 miles from home). I've tested a lot a 6.5 bullets in various barrels (3 Saterns, 2 Sabre Defence, 1 Krieger, 1 BHW, and 1 Criterion), and stick to my belief that not all bullets behave the same with the very first "cold-bore" shot, regardless of which weapon a session begins with.

[LR1955]

I use "cold-bore" as a general term, as I don't really think barrel heat is the culprit in my particular case. I think the issue lies mostly with copper fouling, where as bonded bullets seem noticeably worse regarding first-shot fliers from a barrel left fouled with the same bullet (which pertains to hunting applications).

I shoot almost every day with few exceptions. I've shot my entire life, but for the last couple of years, I probably average at least 4 days per week shooting, almost exclusively 6.5 AR's (Grendel and Creedmoor), with some 5.56 and 7.62x39 mixed in once in a while. When it's not hunting season, I might make 3 range trips in a day (600-yard private range 3 miles from home). I've tested a lot a 6.5 bullets in various barrels (3 Saterns, 2 Sabre Defence, 1 Krieger, 1 BHW, and 1 Criterion), and stick to my belief that not all bullets behave the same with the very first "cold-bore" shot, regardless of which weapon a session begins with.

Drifter:

Roger.... Questions for you out of curiosity.

First, is the first shot within your call area?

Second, can you predict where the first shot will go well enough that you will adjust your sights before that first shot with confidence the shot will go to your good zero?

Thanks!

LR1955

[Drifter]

If it was a barrel heat issue, I think the cold-bore flier might be somewhat predictable. But with the issue being copper fouling with bonded bullets (my assumption), the POI of the cold-bore shot seems random and erratic. It can vary, but first shot often strays as much as 2 or 3 moa (or more).

Still testing theories and bullets in different barrels. But at this point, if there is a need for a "premium" hunting bullet, the Barnes TTSX and LRX bullets seem less likely to suffer from the issue compared to bonded lead-core bullets.

[Harvest123]

This is a new idea to me now. I have always been taught that the cold bore shot would differ from the fould bore. Since I have not taken the time to test this, I have "assumed" this to be true. Yes, we all know what "assume" means, and it apparently it applies to me. What I have always wondered is what is too much fouling to affect accuracy. LRRP, any ideas on too much fouling affecting accuracy?

[LRRPF52]

I actually don't clean my barrels much. If I notice something crazy happen with accuracy, then I'll clean them and take it from there. I also keep a round count log of how many bullets are down the bore, so I have a good idea of when to expect certain things.

I also don't shoot a lot of premium hunting bullets with soft copper that tends to foul bores.

[invisiman]

Hey Drifter,
In your opinion which barrel have you found to be consistently the best? Thanks.

[Drifter]

Hey Drifter,
In your opinion which barrel have you found to be consistently the best? Thanks.

Satern, but they've all shot quite well. Having shot 3 different and very accurate Grendel Saterns makes me believe that they consistently put out good barrels that are chambered in house. I eventually sold two, but currently shoot one with ~5000+ rounds and it's still going strong. Recently bought my 4th Satern to have a standby.

There are several other good brands, and Krieger is considered top-notch. But in most cases, the chambering is done by your chosen gunsmith rather than the barrel manufacturer. With SAAMI acceptance of the cartridge, maybe that will eventually change and the consumer can buy a Grendel barrel finished completely by the manufacturer without the additional wait times of a good custom 'smith.

I believe Shilen has started offering Grendel-chambered AR-15 barrels. I've experienced great accuracy with Shilen barrels chambered for a different cartridge, but not sure how well they can stand up to the high round count that cut-rifled barrels exhibit (such as Satern and Krieger). If I didn't shoot so much, I'd buy a Shilen without hesitation.

[stokesrj]

I am one of those superstitious folks that believes a cold clean bore impact location can be different from the following shots. I have observed this with one of my service rifles. It will always shoot an inside 8 at 5:00 the first shot of the day from a clean bore at 600 yards. The next shot will be an outside 10 at 5:00 and the following shots all X's if the shots are executed correctly. Last year I won four cold bore X challenge coins at Port Malabar with that barrel. That means I compensated for the first shot correctly on four different days in registered matches.
The barrel I have this year does not do this. It will shoot an X first shot clean and cold but does move up 1/2 moa as it warms up on about the 8th shot and stays there through the remaining shots of a 22 shot string.

Both of these are Krieger 1:7.7 twist 20" service rifle barrels chambered with a Wylde .223 chamber.

The AMU also believes that a cold bore / clean bore can have a repeatable point of impact different from subsequent group centers and teaches to verify this over multiple days. http://www.shootingusa.com/PRO_TIPS/USAM...mu6-3.html

Bob

[LR1955]

I am one of those superstitious folks that believes a cold clean bore impact location can be different from the following shots. I have observed this with one of my service rifles. It will always shoot an inside 8 at 5:00 the first shot of the day from a clean bore at 600 yards. The next shot will be an outside 10 at 5:00 and the following shots all X's if the shots are executed correctly. Last year I won four cold bore X challenge coins at Port Malabar with that barrel. That means I compensated for the first shot correctly on four different days in registered matches.
The barrel I have this year does not do this. It will shoot an X first shot clean and cold but does move up 1/2 moa as it warms up on about the 8th shot and stays there through the remaining shots of a 22 shot string.

Both of these are Krieger 1:7.7 twist 20" service rifle barrels chambered with a Wylde .223 chamber.

The AMU also believes that a cold bore / clean bore can have a repeatable point of impact different from subsequent group centers and teaches to verify this over multiple days. http://www.shootingusa.com/PRO_TIPS/USAM...mu6-3.html

Bob

Bob:

Given top end rifles and shooters, if this is true I would believe it. I am not doubting the first shot or shots from a clean bore may not go to a zero. Just that with guys who aren't current competitive High Masters using custom rifles firing custom tuned ammunition will probably not be able to predict where the first shots will go well enough to trust a zero change.

LR1955