by Bush Killer » Sat Jan 15, 2011 6:41 pm
In general, the AK hopup unit design is more consistent than an Armalite of comparable price range. The average AK barrel is around 450mm, compared to an M4's 363mm, and an M16's 509mm. The extra 50mm to go to the M16 length will net only marginal improvements, so if you have a good deal on a nice AK, go with it.
The number one thing in a quest for a DMR is to make sure you have the right internals. Externals can be ignored somewhat, especially if you're one who doesn't really care about plastic vs. metal or trades vs. blank receiver. From the back of the gun to the front, here's what you ABSOLUTELY need to have:
A high voltage battery. This is not to increase rate of fire, but rather to increase trigger response. I personally LOVE LiPo batteries because of their small size and light weight.
High torque motor. Again, trigger response. A high torque motor jumps to a faster start than a high speed motor.
M120 spring. Anything heavier and you'll be shooting over FPS limits. Go much lighter and you won't be able to push heavy weight bbs out to DMR range.
Matching cylinder, cylinder head, piston head, air nozzle and o-ring. This is where the magic happens with air compression. If you lose compression here, you get inconsistencies from shot-to-shot and you're not optimizing your power.
Consistent hopup unit. Your stock gun may come with a nice metal hopup unit, or it may come with a crappy two-piece plastic one that can warp. This is where a lot of people skimp; they buy a nice barrel, hopup bucking and nub, and stuff it into a brittle plastic hopup unit. Get something nice, like a NEO Strike, Systema or Madbull Ultimate chamber.
Hopup bucking. One of the most important upgrades you can buy, and also, one of the easiest to install improperly. Systema, Firefly, and KWA 2G buckings are all good buckings, and are inexpensive. Make sure to wrap the end with a layer or two of teflon tape to finalize your air seal.
Tightbore barrel. There are many choices to make; material, diameter, length and manufacturer, and it starts to get confusing. Basically, you need to evaluate what is best for you. Generally speaking, you want a stainless steel barrel. Prometheus is THE choice for this. At 6.03 and an extremely consistent bore, you can't really go wrong. Another solid choice is the old-school KM TN barrels. They are 6.04, so they won't give you pinpoint accuracy like some barrels can, but their teflon-nickel coating makes for an extremely consistent shot that WILL NOT JAM. I've put hundreds of thousands of rounds through one with no problems. If you're looking for a hotrod piece to center your build around, you want to buy a 6.01 tightbore. These are the tightest barrels you can buy, and require frequent maintenance to ensure you won't encounter jams. These also tend to be the most expensive barrels. EdGI and PDI are both well respected makers of 6.01 barrels. I picked up a MadBull 6.01 recently and have had mixed results. It jams fairly easily despite maintenance, but when it's on, it's ON. Tack driver at 200 feet, and that's only with a 363mm barrel length.
If you can put together the right parts and get them working perfectly, you'll have a rifle that will out-shoot 90% of the electrics on the field. The problem is time and resources. A build like this will take more than your budgeted $200, and requires hours and hours of installation, tweaking and testing.
Not to be discouraging, but the number one thing you should focus on is buying the replica that you like the feel and function of, and then getting magazines and gear for it. Then, buy your upgrades as you can afford them, and slowly watch your replica transform into a rifle you can be proud of.
Proud member of the 973rd COB
"The Artist Formerly Known as
Cain"