Oops. The new barrel is a bit too long for my old suppressor.
For the last two years my custom G36C/K has had an Evike 6.035mm 363mm tight-bore. Recently Evike started offering a new line of 6.03mm tightbores under their Matrix brand so I thought I'd give one a try. http://www.airsoftpost.com/inner-barrels-matrix-barrels-c-24_72_376.html
Tokyo Marui AEG and practically all other clones of TM designs (JG, CYMA, CA, SRC, etc.) have 6.08mm inner barrels. This is the 'stock' diameter which allowed a fair tolerances for variations in BB diameter and shape. Philippine and Taiwanese tuners soon sought higher FPS limits and greater accuracy by experimenting with smaller diameter inner barrels.
Known as Tight-Bores, these barrels have an inner diameter of 6.04mm or smaller (6.03, 6.02 are the smallest mass produced diameters, though DB customs makes a 6.01mm and tighter.) The downside was greater jams due to misshapen or overly large BB's that made it through the factory process. But in the last 5 years, the quality of budget BB's has improved greatly, allowing the reliable use of tight-bore barrels.
The barrel came in a plastic holder with the MATRIX label on it. Capped on both ends with a stopper. Pretty standard for inner barrels.
The end of the barrel was nicely milled and tapered. The finish was clean and well done. A nice touch was the laser etched specs featuring the length and inner diameter of the barrel.
One difference between the older 6.035 Matrix design was the hop-up hole on the 6.035mm was angle cut at the front. The new Matrix barrel had a square cut like most barrels (CA, Madbull, JBU).
I measured the inner diameter just to make sure the makers were being honest about their specs. The CA was 6.08mm
My digital calipers do not show micrometers but when I measured the old Matrix barrels, 3 out of the 4 times, my calipers displayed 6.03mm and once showed 6.04mm. So it's likely based on this variation, the stated 6.035 is accurate. In fact, if Evike had not said these were 6.035mm, a less reputable retailer could have easily claimed they were 6.03mm.
The new 6.03mm barrel showed true to the name and 4/4 times my calipers confirmed the specs.
TESTING FOR PERFORMANCE
My testing procedure was to take a benchmark chrono of my AEG in its current setup. Noting the FPS at each stage with my chrono (taking an average of 6 shots), I would swap out each of the 3 barrels using the same hop-up bucking. Hop-up would be tuned down to minimum.
6.03x407mm Matrix tight bore (New)
6.035x363mm Teflon Coated Matrix tight bore (Current Setup)
6.08x247mm stock CA barrel that came with my G36.
6.035mm Matrix = 417fps
6.03mm New Matrix = 424fps
6.08mm CA = 370fps
6.035mm Matrix = 412fps
6.03mm New Matrix = 288fps/420fps (initial number air leak disappeared after reinstall)
6.08mm CA = 366fps
When testing for FPS, it's important to do more than one round of testing to confirm results. Air leaks and misalignments can occur which can throw off numbers. For example, in one round of testing, my AEG showed a drop to 280fps, which obviously showed I had a big air leak somewhere. After reassembling the hop-up and barrel and reinstalling it came back to the average 420fps. But this goes to show you, that if I had just tested that barrel once, I would have come up with very incorrect results.
I tested each setup by firing 5 shots into a paper target 30ft away. The results may be surprising to some but all 3 barrels showed groupings of less than 2" using .28g Matrix BB's. Longer and tighter barrels give you greater FPS which gives you longer range, but the accuracy of the BB's at range is entirely dependent on the weight of the BB's.
Adding a longer and tighter barrel really makes a difference with shorter barreled AEG's. I really hadn't realized how much until this test. The difference between the stock CA at 247mm and the new 407mm Matrix was over 50fps! It's a combination of both the .05mm in tightness and the 5" in greater length. An old rule of thumb was that you'd get 5-10fps per inch of length but I suspect the gain in FPS is logarithmic and not linear.
Starting at $26/ea these are the least expensive tight bores out there, and the best value in FPS upgrades. The only drawback for me was that the 1" longer barrel meant that I can no longer use my pistol silencer to cover it. Oh well, that's my excuse for buying a new suppressor.
To change your barrel, you need to disassemble your hop-up unit. For a guide on how to do that, read here: http://www.moondogindustries.com/forum/viewtopic.php?f=47&t=127
Barrels Available exclusively from Evike.com