jackpinesavages said:
First, you will have to be more open to some new things.
I am open to new things. After all, I am here listening to you and 1stmarine tell me that it is possible to shoot XM193 sub-MOA at 100yds, even though I've been shooting AR15s and M16s for over 20 years now and have never accomplished or even seen that feat performed with anything more than a 3-round group.
That RIA study you are referring to is going on 40 years old. I'm not sure WHY you are referring to data and research that is almost 40 years old, particularly a government study, but just barrel metallurgy and ammo.
Yes, it is 40 years old because the accuracy standard for M193 was established as part of MIL-C-9963F in 1976 and hasn't changed since then. In fact, MIL-C-9963 hasn't been amended since 1999 when the accuracy standard was the same as 1976 - an average mean radius of 2.0" at 200yds, which would give an extreme spread much higher than what 1stmarine reports. And that is from a test firing fixture - which pretty much eliminates all human error.
Federal XM193 is an M193 clone manufactured from the same components as M193 and in the same plant in many cases. So it should be very similar to M193.
However, since the results of that test are pretty much inline with every accuracy test of M193 (or M193 clone) ammo I have ever seen, there are plenty of more recent examples if you would like to see them.
Here is an excellent test of M193 clones by Molon at AR15.com (as a bonus it has a picture of a test firing fixture so you can see what that looks like). He used a 16" Colt HBAR. The best performing M193 clone load had an average extreme spread for 10 rounds at 100yds of 2.79" - which according to 1stmarine is almost twice what he should expect from that barrel.
Second, match your variables to 1stmarine's stated variables.
I've got a little over 20 years experience owning, building, and shooting AR15s and M16s. During that time, I've never personally fired or even seen any M193 or M193 clone shoot a sub-MOA extreme spread for any group of more than 3-shots.
Fourth, I mean these things in the nicest possible manner. In firearms training the biggest hurdles and limitations I see with students is themselves, and not the firearms or the ammo.. YMMV.
Based on the quality of your commentary thus far, I think having you as an instructor is probably your student's biggest limitation; but I mean that in the nicest possible manner.
1stmarine said:
A) AR Match barrels are extremely accurate many times going mano a mano with the best bolt systems.
B) A match barrel is not guarantee of extreme accuracy with a particular load, commercial or not. What we commonly hear as "my barrel doesn't like this load".
I think everybody here understands that. We have a fairly good group of shooter who do actually get out and shoot. The problem I am having is that I've never seen that kind of performance from any barrel - EVER - in 20 years of shooting and watching others shoot. And you are telling me you've got four different barrels that are nothing particularly special that all perform that well. So I am having a difficult time reconciling my own personal experience with what you are saying.
C) Heavy barrels in 16" are also extremely accurate, even "low-tier" systems (Whatever that means). All other things being equal, a short barrel is more accurate than a long one. You loose a tad speed but that is a different subject. This doesn't mean a long barrel can be more accurate than a short one with a specific load. Many times they are but what I mean is a simple matter of physics.
As I mentioned earlier, I'm using a 16" Lilja stainless steel match barrel with a hybrid chamber. It is a medium profile at 32oz. It will shoot Hornady 55gr boattails sub-MOA. it will shoot pretty much any match ammo sub-MOA. The best it has ever shot any XM193 load is a 5-round (not 10) group of around 2.5" at 100yds. It meets every single one of the criteria you have named as necessary (unlined, short barrel, heavier profile, hybrid chamber, match barrel).
Yet I'm not seeing sub-MOA. I'm not even seeing the groups you state I should get from a chrome-lined 1:7 standard run of the mill AR barrel.
Apparently, I can shoot sub-MOA with other ammo, so I am mystified why I am not seeing that performance with XM193 if it is capable of it.