Cheap M16 Velocity Reduction

[Switchback]

I have an M16 that shoots kind of hot for playing CQB (this isn't practical, M16 indoors and all that its just a thought) and even a little sinister for outdoor. I also happen to have a spare stock barrel lying around and thought:

Well, a tightbore increases velocity (I know it increases accuracy too) by putting more air BEHIND the BB.
If I take air pressure from behind the BB, then it will reduce the velocity, allowing me to play indoors/not be the guy who punches wholes in people.
I take my extremely small drill bit and drill holes in my spare stock barrel near the hop up unit and all the way down the barrel. I, not being a noob, I would use a small drill bit and take it slow, producing clean holes without too much excess metal hanging into the barrel. Still, basking in not-noobishness, I clean the barrel and install it in place of my hypothetical TBB. Air wooshes out of the holes when I pull the trigger, sending a less vicious piece of 6mm plastic on its merry little way.
This could be handy for those who bought an Echo1, JG, CA, etc., and upgraded their barrel to play outdoors, pushing their FPS up into the 380's. Its a cool way to get indoors with the same gun without changing uppers or spending time/money to downgrade. I'll post pictures after I finish mine.

[Sahronax]

Alternatively, you could just downgrade your spring...
Although this is an interesting concept, what size drill bit did you use?

[dom186]

Check thus out. I didn't read your entire post so I don't know if you mentioned it already.

http://shop.ehobbyasia.com/pro-arms-muzzle-velocity-reduction-adaptor-14mm-cw.html

[dom186]

Sorry for the "thus" I'm doing this on my iPhone. The theory is nice but I don't think it will work. There is no place for the air to go. It's like putting a barrel around a muzzle break. In an airsoft gun there is a barrel in a barrel, so drilling holes in the inner barrel will do nothing as the outer barrel is preventing airflow out. Most airsoft guns have pretty low tolerances between the two barrels. It would only work if you drill the holes through both barrels, but then you ruign the outer barrel also. Hope that makes sence.

Look up the YouTube videos for the velocity reduction units. They supposedly work great.

[Regular Guy]

Bleeding the barrel to let air pressure out and lessen FPS is the idea behind Madbull crawler barrels. Unfortunately they only made them in 300mm length.

[youtube]http://www.youtube.com/watch?v=FPK9MIJRrhA&feature=player_embedded[/youtube]

If you do this on your own, make sure to clean the inner barrel thoroughly of excess metal shavings.

[Jewish Ninja]

Those velocity reducers never work in FA either, they are really meant for semi auto.

What your doing "COULD" work, but its also very possible that it'll make it as accurate as a blind man.

[dom186]

I agree with Jew. I have taken machining classes at my school for three years and the chances on messing up your barrel are very high, and your "cheap" mod will soon become very expensive when you have to buy a new barrel, iif you screw up. Even if you did it right, there's a high chance it'll just screw up your accuracy or not do anything at all.

Just swap springs and you will be guaranteed to not mess anything up, unless you screw up your gearbox, but if you're brave enough to drill holes into your tightbore barrel, I'm sure you are brave enough to open up your gearbox and figure out how things work in it.

You could drill holes into your cylinder, or you could buy a cylinder with either longer or more air ports. Cylinders are pretty cheap too. This mod will make your gun inefficient, but you were planning to do that anyways.

You could take a tooth off the front end of your piston. This will increase rate of fire but will "short stroke" the piston. But it would be more effecient than wasting air. Replacement pistons arent too terribly expensive. It will also drastically increase rate of fire. So you would ve able to kill two birds with one ston! You could also remove a tooth off your gear that comes in contact with the piston which will basically do the same thing. You might also be able to cut off a few coils off the spring, but it could just screw things up. Finally, you could just buy one of those newish madbull lithium batteries and fire only in full auto. The airsoftgi review dude said it shit solo fast the piston didn't have time to complete a full stroke before the gear grabbed it for another cycle. Those batteries are pretty expensive. I never realized how many options we have for reducing fps (or in other words making our guns more ineffecient)

Note: this was all typed on my phone so it is probably messed up a bit

[Switchback]

@Dom186: I know there is not much difference between the inner/outer barrels but it could still work.
@Jewish Ninja: Accuracy isn't a problem; this is a personal proof of concept, if you will.
@Virus: I made a 14mm CCW velocity reducer too; It is an M4 birdcage (orange, plastic) with the heads of trimmed toothbrushes forced through the flashider's slots. It works, but cuts the head off of my accuracy.
@Dom186(last post) I'm doing this to one of my 3 M16 STOCK barrels. My TBB is in the mail, getting it from a friend in Missouri. Most (meaning all of my 4-5 TBB's, barring my buddy's M11) TBB's are made of a fibery kind of material that makes them easier to make with less tolerances.

Keep in mind this is just something that I wanted to put out there. I am going to end up just getting a 9.6 and downgrading the spring. If this works well without seriously warping the STOCK barrel, not only will I be surprised, but kind of elated that it worked.

[dom186]

If you were going to do it regardless what we had to say then says in your post! I'm interested to see if it works. I thought about it more and I do think it's possible for it to work. The lower pressure air inside the little holes you drilled would be replaced with the higher pressure air that is behind the bb, and if you drill enough of them it could have a drastic affect on the among of pressure behind the bb. I don't know if that's your theory, but if it does work, that is how I see it working.

I say go for it and tell us how it goes!

[Switchback]

UPDATE:Dom, I was drilling, and its tough. I got through about 5 little holes, and checked the barrel for shavings. After cleaning those, I noticed the barrel lost its integrity. So I picked up Stock barrel #2. I cut little slits in it every inch on the top, and in between those on the bottom (for the first 1/2 of the barrel, excluding the space for hop up units). Then I lengthened the gaps and did that until I was about 3 1/2 inches away from the end. I made 21 cuts, and the barrel is relatively smooth on the inside. I hope to install/test tomorrow because I still have to charge my battery. I am going to run small bits of steel wool through the barrel because a bb wont roll through it without shaking it yet. I hope to see an increase in smoothness after a bit of steel wool and water rinse. If I stick it over the barrel of my sniper, I can feel the air coming out of the holes. I hope it works; wish me luck. I hope to have this complete before Friday night.

[Beran]

since a barrel change is so simple, you could do some pretty easy comparison tests once you are done. i can see this going either way, the principle is sound but there are other factors that are going to affect it as well.

once you are done, run both barrels in a gun through a chrono, and then do some accuracy tests at around 25 feet or so. do it all on the same gun and with the same ammo so the only variable is the barrel itself.

[Sahronax]

I am sure this sounds stupid but I just want to be sure, you are going to chrono it and post the results?

[Switchback]

I don't own a chrono, so I'm showing up as early as I can at Snowmageddon. If it isn't inconvenient, then I'll chrono both barrels. Its on a JG, so it should be interesting. Chronographed at 390 to 408 brand new. It should cool off eventually.

[Switchback]

I cleaned it out; no hanging metal. The only problem is a little bit of fuzz from my cleaning patches. Shooting starts at 2000hrs tonight!

[Switchback]

Sorry about getting back to you guys so late. I did it, and used it at Snowmageddon. The accuracy is still there, and takes about 50 FPS off. Got a couple kills, and now my M16 is CQB ready (pshh.)