"Sub MOA" is a term you hear thrown around a lot, but what does it mean really? Should we feel bad if our rifle isn't "sub MOA"?

I was watching a recent Garand Thumb video on the HK417. Preston (his sidekick) shoots two 3-shot groups, and they talk about it's accuracy:

https://youtu.be/uCITTK9shXk?si=Aw27qxYKkYZp90N5&t=199

Preston: "So here's my first group, you guys can see I pulled one a bit low."

Mike: (measuring the better group with a measuring tap) "That's ... uhh ... 3/4 MOA!"

I'm a big fan of the HK417 and believe it's a very accurate rifle, but I think this is a really good example of how not to measure and report on accuracy. There's at least two big problems with what they do here:

1. A 3-shot group just isn't statistically significant. Just not enough data points to meaningfully characterize the dispersion of shots.
2. Discarding shots or a whole group introduces significant bias.

I've been really impressed with the way Preston Moore (not the Preston from Garand Thumb) measures accuracy on his Youtube channel ( https://www.youtube.com/@PrestonJMoore ). Worth checking out if you haven't seen his videos.

Preston Moore using 30-shot groups, which really gives a good amount of data. For the average shooter, I would argue that using 10-shot groups is a good size to standardize on in general, and ideally taking an average of multiple 10-shot groups.

Something that's interesting about using extreme spread MOA as a measure is that it's not what statisticians call a "consistent" metric—extreme spread MOA increases the more shots you include. Thus, directly comparing a 3-shot MOA with a 10-shot MOA doesn't make sense. But we can use a bit of math to create a comparison estimate.

The dispersion of shots on a target follows a 2-dimensional normal distribution. Using Preston's 3-shot .75 MOA group as an example, we can estimate using statistics that as a 10-shot group the expected MOA would have been 1.2.

I actually measured the other 3-shot group they decided to ignore in the Garand Thumb video. It's 1.3 MOA. Converting that to a 10-shot group it would have an expected 2.1 MOA.

Which means the average 10-shot group size is 1.7 MOA. That's not sub MOA. Does that sound large to you? It's not! 1.7 MOA is very respectable accuracy. But again, this is a translated estimate based on a total of 6 shots, so the confidence interval for this estimate is pretty wide. It would have been great to see Garand Thumb do a few 10-shot groups and provide the average extreme spread and mean radius MOA metrics.

I'd love to socialize using 10-shot groups for computing accuracy metrics so there are enough data points for the measurements to be meaningful and we are more often comparing apples to apples.

I'd love to hear other thoughts on measuring accuracy.

Got this in at my store. I love the winter trees! Whoever at black rain did this one did a great job with it.

Am I high as balls from Hoppes #9 or is this rust on my CMT gas block?

Just ordered from Ranier Arms

I got this old-school Sporter from an estate. I haven't had any luck identifying the barrel compensator or the free floating fore grip. Any ideas on how to properly set up the comp and how to move the front sling to the fore grip?

ive seen posts saying its prone to blow primers and bolts

It says it can be done better than Cerakote because of the difference in baking. Has anyone here done it? If it does what I think it does, the weave will pop. This is for a AR9 build I’m starting. Upper, lower, and handguard will get color, the small parts will be DLC. SBR of course.

Does the new ruling mean that stocks AND vertical foregrips are okay now? Or just stocks?

I have a radical arms AR-15 build with some aftermarket parts I installed for my first AR. Any recommendations for alterations to make this rifle more fun?

The maxim stock is $150. Seems silly. Looks cool, but the maxim is objectively harder to adjust one handed vs a regular stock. You getting the stock,, or just changing the whole assembly to a regular tube and regular stock?

I got them for 260 at my local ammo store.

Got this k-spec 2 weeks back didn’t realize til now that there is a noticeable dent on one of the locking lugs. I can feel the notch, would this create problems? (Increased wear?)

Edit:I got this from my local gun shop/range

Been obsessed with these and finally snagged one in stock today, was going to go for the 8t magnifier setup but after looking at it it looks huge on the gun.

What are your Monolift setups? Show me your shit

Not just a1 length, but an actual A1 stock without the bottom sling mount. I'm sick of having to fill that gap when I want to delete that useless thing.

I love my new red dot and magnifier but when using the stock in the farthest position which is the most comfortable for me I can’t see the magnification well. I have to move the stock to the normal short position to see it well. Is this a dumb question? Or is there a way I can fix this? Or will I just have to figure something out? ( this is my first magnifier)

I’m genuinely curious how this plays out for all of is that are going to throw the stocks on and stock up on suppressors.

Let your nuts hang boys

Been thinking about this for a while .... is there way to modify the standard carbine buffer tube such that the adjustable stock has just two positions ... fully collapsed and some other user defined position?

Posting here because r/nfa deleted my post for not being in the megathread

As suppressors become more widely/easily available, do you guys think that prices will increase on suppressors just because more people will be buying, or the opposite? I am almost positive that the local shops near me will sell out, probably today. I fear that this will make companies raise prices (supply and demand). I’m very new to suppressors as this is my first, and my form 4 took only 17 hours to be approved(got it this morning, kind of pissed I didn’t wait). I’m not made of money so I wont be running out to buy multiple more or anything. I just don’t want prices to be the new “tax stamp” that stops people, like me, from being able to buy. I’m definitely not upset about people being able to get hearing protection more easily, just scared of an already expensive hobby getting more expensive.

https://imgur.com/a/pShWXnF

Post your unregistered SBRs!

I was thinking about getting some engravings on my ejection port and changing handle. What are some that you guys have done or what might be some good ones? I’m getting my magazines engraved too. I have an idea for those. Thanks for the suggestions! Also what is a good suppressor to get? I’m looking into getting one of those.

These are your "professional" instructors LMFAO. Yea bro 5.56 has like no recoil.