I'll try to help out with the weight questions.  The uppers that Zak and his buddy got weigh 4 lb, 4 oz. without optics. You can add 2 lb., 3 oz. for a complete lower with LMT/Crane stock and 14 oz. for a TA11. That comes to 7 lb., 5 oz. for a complete rifle, sans magazine. Other stocks, optics, etc. will change this but I have one set up exactly as above and it weighs 7#-5 exactly.

Nice group Zak! Once that Krieger settles in you will have a hard time putting it through the IRTC.

Reliability over time is a fair question.  We did the original design of our 17" comp upper for Taran Butler just about a year ago. He shot our uppers the entire season, February to September. He won all the 3-Gun matches he shot, including every national level match, and beat the Open Division shooters in most of them while shooting Tactical Division himself.  Pretty good testimony as to the reliability of the system, I'd say...

The reason we built the 17" was simple. On some stages a shorter gun makes a difference. Manuevering in narrow passageways, in and out of ports, etc., is easier with a shorter gun.  The goal was to get the shortest barrel that would still operate reliably.

The lightening of the carrier is not an idea that came from the competition world. This carrier design is one that Dan Young did for the SEALS quite a few years ago. They were looking to reduce the reciprocating mass to speed up cycling and to get quicker second sight pictures. By using a lighter carrier and a lighter recoil buffer they were able to make their M4's run very well in semi-auto, their preferred firing method.  According to Dan, the realities of their resupply logistics made it impractical to have separate NSN-designated spares in the supply chain and the program was abandoned after a time.  He had a small quantity of these carriers left in inventory, which he sold at various gun shows around the Southwest over a few years time.

A few eventually found their way into the hands of 3-gunners who liked to tinker and they found that the way a gun handled could be radically affected by using different combinations of spring tension, gas volume, and reciprocating mass.  While it is easy to make a gun run poorly by randomly applying these types of changes, it is also possible to speed things up significantly with no loss of reliability. While it is true that the shooter is the biggest factor, the difference between winning and losing a close match is often a cumulation of many small things that are a tiny bit better.  After getting many inquiries about the lightened carriers, we went back to the source and asked Dan to do a custom run of them for us.  They run fine as a straight drop-in replacement. If you want to get more out of the weapon, the carrier makes other adjustments possible.

Not to imply that the reason for Taran's success was our rifles, only that he came to us dissatisfied with what he was shooting and asked us to build a platform that worked for him.  After a year, so far so good. We continue to tweak here and there to try to improve the package. I just shipped two of his guns back to him after making minor mods, and have another of his here to do the same.  Bottom line is, he had more confidence in equipment he liked better, it showed up in his scores, and he ran the table in 2004.

When Zak talked to me about his uppers, and specifically for using in the IRTC, consideration had to be made for the extreme nature of that competition. That kind of heat does strange things to a rifle. We use Douglas and Lilja barrels for most of our custom contours with good results.  Both use SS alloys with nominal tensile strengths of around 150k psi. Krieger SS blanks run around 180k, so provide a higher tolerance for the effects of extreme heat.  While the effects of a stint at the IRTC can permanently damage any barrel, we felt that this one would have the best chance of survival while still providing a lightweight package to carry across the courses of fire.

Barrel life will always be a huge variable. I know guys who have gotten a borescope and ruined every barrel they had trying to clean them to perfection.  JB will remove the lands if you use it often enough!  That said, a good 3-Gun barrel should last 8-10k rounds, maybe a lot more if you are satisfied with 1.5-2 moa accuracy. A highpower shooter might get 5k out of a Krieger before accuracy drops off. But that drop off is small, maybe a couple tenths.  A 3-Gunner will never notice if group size goes from .5" to .6". Ususally it happens when plates no longer move at 300 yards consistently. 99% of the time it's from a damaged crown or a dirty barrel, not because the throat is gone.

Now barrel life can be shortened dramatically by a trip to the IRTC.  Watching a SS barrel turn from grey to purple to tan is a life-changing experience. The finish will never recover. Sometimes the bore does, soemtimes it doesn't.  That is what new barrels are for, to help us get on with our shooting lives.  The old ones make great conversation pieces though! Kinda like the first time you crush the face of some titanium jumbo uber-boomer driver on a little bitty golf ball. At first you are mad that it broke, then see how cool it was that you did it.

Just a note on gas blocks.  Aluminum blocks work fine for 3-Gun. We use them when customers ask for them. But here's the rub. All gas blocks slip over the barrel. They need a minimal amount of clerance or they won't go on. This means there is a small gap, can't be helped.  Mechanical pressure keeps them in place. So can loctite (up to 500 deg for Red), or Rocksett (2100 deg, and it's "permanent", unless you want to destroy the barrel).  But there is vibration to loosen the mechanic lock and heat, sometimes a lot, that can break down anything that isn't permanent.  A little extra security can be had by matching the materials of the gasblock and the barrel. With matching expansion/contraction rates it is less likely that things will move. We also hone our gas blocks until they are just short of sliding on. Then we heat them up. They slide onto a cold barrel easily when hot, but don't wiggle at all when cooled back down. That is with 250-300 deg. applied.  Aluminum heats and expands much faster than any steel. That is why they come loose when barrels get really hot.

The lighter carrier does go faster, and with appropraite changes in springs, buffers and gas volume, can be tuned to go all the back in a hurry, but still not bounce the buffer against the bottom of the receiver extension (buffer tube for everyone from Rio Linda, har har har).  By eliminating, or at least minimizing, the secondary recoil pulse from the carrier's rearward movement, the gun position is disrupted by a lesser degree.  By the same token, reducing the total energy going forward to load the next round, again faster but lighter, keeps the reticle on target better.

I have tested a lot of different ammo through these at typical 3-Gun targets and ranges.  While 69-77 gr match bullets are more accurate and less prone to wind drift, the difference is not often translated into better actual performance. If targets were beyond 300 yards on a regular basis, out to 4-5-600 yards, bullet selection would become more important.  I have a practice facility that offers open terrain out to 400 yards, across valleys, up and down hill, and where winds are often gusty to 20-30 mph. Comparing with a timer, I can honestly say that the longer bullets are not a big advantage for me. If accuracy is the only criteria I can get a higher percentage of hits with 77 gr SMKs in the wind. But add speed into it and the results level out. The faster you shoot the more you miss. Shooting 55 gr is faster than 77 gr over the course of a typical stage, and walking a miss in with a bit of Kentucky windage keeps the 55 gr FMJs competitive for me. My absolute favoprite is a 52 gr flatbase ballistic tip, but the cost isn't worth the benefit.

Pressure is largely a non-issue in 3-gun as guns that shoot fast and soft are more competetive than ones that push the limits. No need for moly and more powder in this game, IMHO.

I have not personally seen JP blocks loosen up, but have heard confirmed reports of it happening. I have seen Smith aluminum blocks move though and more than once.  Other than the sever conditions of an IRTC-type outing, the common reason is poor block to barrel fit (too loose to start with).  Our take is that since these guns live or die on the gas system functioning, it's critical to get that right. We do install the JP blocks and have confidence in the for normal shooting. We do fit them very carefully however to minimize any tolerance between the barrel and the block bore.

C_C,

We use different gas port sizes for a lot of our custom barrels.  Especially the comp stuff where we are using adjustable gas blocks to tune the gas system.  Email me off line if you want to discuss further. I don't want anyone to start ripping case heads off by opening up a port too large. (Funny how simple concepts turn into disaster on the internet!).  

The short answer, ports for 17" and 18" barrels are the same, sometimes. There is little margin for error on the 17's though. One reason we shoot every one.  I had one the other day that functioned 100%, until I put it in the freezer for 2 hours and shot it cold. Function dropped to 90%. With cold ammo, dropped to 60%. This particular customer  needs his rifle to function 100% in some pretty severe conditions.  After some minor tweaking, it does.  He even got special lube and instructions on how to keep it 100%.  We aim to please.

The point on reliability is well taken.  Anyone who knows us is aware that we take reliability seriously. Many of our customer's lives depend on it. That is precisely why we decided not to go as light as the JP aluminum carriers.  They are extrememly light and a dream to shoot when they are running well, but JP folks will be the first to tell you that system is not satisfactory for a work gun.  Our lightened carrier is roughly 13% lighter than a full-auto M16 carrier. enough to make a noticeable difference in carrier movement and to make the gun run faster in semi fire.  That alone is a slight advantage over a std carrier.  The fact that it is a NM profile and locks up in slightly better alignment can have a small difference in accuracy. (Good barrel, good ammo, good trigger all have way more bearing).  They will run in a standard AR with no modifications, just slightly faster.

If I could consistenly get 1/4 moa out of a lightweight AR, I would be too busy accepting my Nobel prize for changing the laws of physics to post on this board!  I'm happy that Zak's upper is shooting as well as it does, but take no credit for anything special there.  Maybe it's a moon and stars alignment thing.  I do know that the bullet manufacturers will often admit that their product is not that good. IIRC, SMK's have nominally between 0.5 and 0.75 moa concentricity dispersion in a typical run of bullets.  This can be reduced by sorting and culling, which is what a lot of top shooters do, but they still aren't perfect.  So while the occasional group might be exceptional, shooting better than the bullets can fly is, over the long haul, territory where only skilled alchemists can walk.  Not mere mortals like me.

Side note, Ross is as good as I have seen with a 226 (his usually last around 200k before the frames crack). He is shooting a new MRP carbine these days though, with a QC Brake on it.  It's the hot setup for M.I.S.S. Rifle Mania!