Do tightbores bring down the FPS?
 

I am looking at buying a sweet AIMS-74 (Romanian AK), one problem its rated at 453fps!! Will at 6.03mm tight bore bring down the fps to 425 or lower (JOC regulation)

im pretty sure that will increase your velocity, you may as well just do a quick spring swap, they r like 15 bucks

No, they will bring it up around 10-15 FPS on average. Like specs said, get a new spring :)

i think if you go tighter it will eventually start bringing it down but then you risk frequent jams unless your aeg is super precise

453fps? cybergun romanian ak ? .12BB?

How so? I was under the impression the FPS increase was because less air escapes around the BB, but rather stays behind in since the diameter is close to the BB itself. You are right about the jamming though, since any dirt or impurity of a BB would change its size, being TOO tight will cause jams.

ya im not really too sure about it...bottom line is its not worth it :)

tightbore will increase fps not bring it down, wtf yall smoking

and yeah a spring swap is what you need not a barrel swap

If you're not sure about it, don't give advice.
Pus is right.

^This. Get it to an actual chronograph with some 0.2g BBs first. Chances are it's under 400.

The BB never touches the wall of the barrel, if it does, it causes extremely inconsistent accuracy and frequent jamming.
Going to a 6.03 increases fps by 10-15
Going to a 6.01 increases fps by 15-20

As was stated, the best solution is the simplest one; get a different spring.

And in case anyone was thinking it, using heavier BB's doesn't reduce your fps..... good to throw that one out there every now and then....

Oh I know, but I was just saying that too tight of a tightbore like 6.01 jams form much easier, since there is less "space" so to speak for error.

Actually the BB bounces its way out the barrel, probably more so in a tightbore but the magnitude is less. However a barrel like TK Twist creates an air cushion around the BB, thus increasing the shot consistency.

That's half correct, if the BB bounced all the way down, you'd get REALLY bad accuracy because the exit direction would be random more frequently. And the longer the barrel, the more it would bounce, and the lower your FPS and accuracy would be because on a 650mm barrel it would bounce so much that it would nullify your backspin.
It does, however, bounce after it's hits your hop rubber. But it re-centers itself as it goes down the barrel. Thus the idea that a longer barrel increases accuracy.
However as long as you have the proper pressure behind the BB, it can re-center itself VERY quickly, as in a pistol. Thus good compression = amazing accuracy

However the HUGE downside to TK barrels is that there's so much air that goes AROUND the BB due to the huge air channels around it, that it's more likely to bounce around.

I've never had any issues with accuracy, range, or trajectory on smoothbore barrels. Don't need to re-invent what already works great :)

Alright thanks, Ill downgrade the spring. Also if everyone is thinking of the retailer I am buying from (the pink one) how accurate are (un-named) retailer's FPS checks?