How much of an improvement could I see from a 6.03mm tightbore barrel?
 

I've been trying to research how I could improve the accuracy of my stock CA M15A4 Sportline Rifle (SP003P-1) and so far I've found two things that could help me with that: running BB Bastard airsoft BBs and having a tightbore barrel. I've already ordered some BB Bastard 0.25g airsoft ammunition, but I have a question.

My airsoft gun currently has the stock CA 6.08mm 509mm barrel that came pre-installed in it, and I'm wondering, based on your experience, how much better does accuracy get with a tightbore 6.03mm barrel, compared to stock barrels that are 6.05mm-6.08mm in diameter?

I'd like to know before I make another good investment on my airsoft gun. I primarily use it to shoot targets, and therefore accuracy is one of my biggest concerns (that's why I got a long M16A4 instead of the typical M4A1).

These are the current results I get with accuracy, shooting a 10m air rifle target at the required distance of 10m (~33') indoors, with my stock airsoft gun and 0.28g Javelin BBs (I've circled two of the off-center shots in red):
http://img651.imageshack.us/img651/2...ineaccurac.png

If your going from a 6.08 to a 6.03, you will definitely notice a difference in accuracy. More specifically, your groupings will become tighter. You'll probably see a bit more as far as range goes as well.

When you do install it, check to make sure you aren't firing too hot as the added pressure of a tightbore barrel will increase the air pressure bringing your fps up a bit.

Good luck friend and welcome to airsoft!

Thanks for the quick reply Towe1ey. Now that I know that I should get a 6.03mm barrel, would this $40 Mad Bull here be a good choice? http://www.airsoftparts.ca/store2/in...roducts_id=299

I unfortunately can't spend big bucks on a barrel (like a Prometheus) due to my budget being tight.

Madbull barrels have been known to be good budget TBBs.

Would I see a good improvement in accuracy (along with FPS and range) with a budget Mad Bull TBB over my stock 6.08mm barrel?

I don't have a chronograph to confirm the current FPS of my M15A4 airsoft gun; all that I know is there's a sticker on the box in came in that indicates it fires at 393 FPS. Based on experience with upgrades on other similar guns, would I still be within the typical FPS limit of an outdoor field with a TBB?

Just make you install it properly/carefully, take the time to ensure you have good consistent FPS (air-seal with your hopup/nozzle and such)

You can buy the highest quality parts, install them improperly or have something else not functioning correctly, only to get shitty results.
It's not hard swapping out for a new barrel, but mistakes can be made and have with all things. Just make sure to read up on it, take your time and you will be golden!

Getting a chance to chrono is always a safe bet. Just because the box says X FPS, doesn't mean it is so. Could be a lot hotter, a bit, pretty close or totally far from it.
Generally you can expect 5-15 fps increase, give or take from a TBB.

Best of luck!

I would advise that a lot more can be done for accuracy for less money, upgrading your hop up and tuning it will illicit much more profound results than a tight bore, perhaps consider both?

+1, although the sportline internals in general are crap, you'll always get better results from upgrading your hop rubber than upgrading your barrel

or clean the crap out of your barrel but be careful not to damage your hop up rubber

Would a hop-up upgrade be the entire hop-up unit (CA Sportlines use a plastic unit; I've heard metal units are better) or just the rubber hop-up bucking that goes on the barrel?

I regularly clean my airsoft gun barrel after each use with the supplied cleaning rod, a couple cut-out strips of paper towel, and a little bit of airsoft silicone oil. I always make sure my hop-up is set completely off before I do my barrel cleaning.

You can buy just a hop up bucking (the rubber) instead of the whole assembly which will render decent results.

Would this be a good piece of hop up rubber? http://www.airsoftstore.ca/index.php...roducts_id=164

They say it's their "go-to" rubber for standard AEG buckings, but I'm a bit concerned of the 50D (50 degree) rubber, which seems a bit soft for a higher FPS airsoft gun like the one I have (if it's anywhere around the 393 FPS rating on the box).

Would it be necessary for me to replace the hop-up rubber though? My CA M15A4 airsoft gun already has decent accuracy in its stock configuration, IMO, so maybe the hop-up is still good (the gun's not even a month old):
http://img651.imageshack.us/img651/2...ineaccurac.png

I wouldn't say that it's necessary to replace it, unless it is crap or worn out. Still, for the price of them, if the one you buy ends up being worse, which it probably won't, at least you haven't spent big bucks in the process.

Would the PDI W-Hold bucking I have linked above be a direct drop-in replacement (no modifications or anything) for a standard hop-up bucking?

That's something that I'm unsure of. Have you tried searching on Google as to a similar situation with the same gun? I would try that first. Chances are if you've got a problem, someone has already been through it. Sorry I can't be of more help, I run a gas gun so I can only speculate.