Doin’ the twist

SO,  you want to drill holes in your barrel?  First off let me say that even buying the common home tools (not even machine shop stuff) to do it properly will likely cost you more than buying an aftermarket barrel. Second, you could very well ruin your barrel both cosmetically and physically, in which case you’d have to buy another barrel anyway. For those reasons I don’t recommend anyone try this. But that’s not going to stop me from telling you how I do it.

Why drill holes in a barrel? Realistically, in my opinion, the only positive effect you can prove is noise reduction. Ported barrels are generally less noisy than non-ported barrels on the same gun. The biggest disadvantage is they are a mess to clean when you break a ball in them, because the paint gets all in the holes. Accuracy? I’ve seen no definitive proof of porting making a real difference, although there is some fairly sound argument for it. Some manufacturers claim the holes relieve excess gas which could disturb the ball as it exits the barrel.  Back in the old days of paintball, people used to talk of matching your valve timing to the length of the barrel to combat such a problem. I suppose I can see the argument that relief holes would make that tedious task unnecessary.  I have had some very accurate guns which had no porting at all.  Nevertheless, porting can look and sound cool.

The first thing needed is a barrel. A good extra, just-lying-around-doing-nothing, throw-away barrel, intended for experimentation works well. I do this with mostly common home tools. If I had access to a machine shop it would be much easier, but I don’t.. yet. I find a drill press is a must to make this work. You simply can’t do this by hand and expect it to come out straight. I got lucky and found a drill press at a yard sale for $50, and have seen them on sale as low as $100. The next tool is a vise to hold the barrel. A regular vise cannot only mar the finish on the barrel, but is hard to get lined up with consistency. Special units are made to specifically hold curved surfaces and work well with paintball gun barrels. The one I have came from Sears and cost about $30. A barrel hone will have to be used to clean up the inside of the barrel once drilling is complete. Some paintball dealers still carry them. They used to cost about $30. Good sharp drill bits help. And finally masking tape, a pencil or pen, and a ruler are necessary.

The dotted line..
The first step is to decide on the twist. I have done barrels in a number of ways, and from a performance standpoint this appears makes no difference. What you are looking at here is a cosmetic affect.  If  I am trying to be very precise about where the holes start and end, I could mark exactly where I want to start and end the twist with tape.  Most of the time I just experiment by tearing off a piece of the tape and wrapping it around the barrel in different twist just to see what looks best. This experimentation is aided by having the barrel on the gun so that top dead center can be marked on the tape.  For the purpose of this article, I will make one complete twist in about 3.5 inches, starting about a half an inch from the top (muzzle end) of the barrel.

Once the tape is set for the twist, the next step is where being precise counts. Using a ruler, I mark along the edge of the tape at a specified intervals where the holes will be drilled.  The intervals are decided by two things – a) what I’m in the mood for as far as looks, and b) the necessary size of the holes.  The size of the holes will actually make some difference in the report of the gun. Drilling tiny holes will have no noticeable effect on some guns. For this reason, I usually like to leave some room to play. I may start off with small holes, but leave space in between in case I later want to enlarge them. Putting more holes in the barrel is also an option, but going too far down the barrel with holes could have an adverse effect on efficiency.  For this barrel, I will mark the holes 3/8 of an inch apart, and use a 1/8 inch drill bit.
To the Drill Press, Batman!
Here’s another area where being precise as possible is important. I line up the barrel in the vise, and the vise itself so that the drill bit is at the very top of the barrel, pointing directly at the mark on the tape. I check this from several sides and lock it down. For this type of pattern and to stay consistent, it is important the bit hits on the top-dead-center of the barrel. This will also help keep the bit from slipping off the mark when pressure is applied. On this project, the drill bit will pass completely through, making two holes. The stop on the drill press is adjusted to allow the bit to go to the proper depth, but not much further, to avoid having the drill itself hit the body.

It’s now time for the drilling to begin. Consistency and patience are the keys to success here.  Regardless of how the tape is marked, hitting each mark consistently is what will make this work.   Before each hole is made, the vice should be locked down, and the bit should be brought down to the barrel to check alignment before drilling starts.   When drilling begins, the process should be a slow one.  Getting in a hurry only serves increase the likelihood of mistakes .  In between drilling holes, it helps to blow away metal shavings.

Once the drilling is complete, the tape can be removed to view the results.  One cosmetic trick is to put a slight counter-sink on the holes. This cleans up the rough edges a bit. It’s done by hand, using a slightly larger drill bit than the one used to drill the holes.  The next step is to hone the barrel.  Before doing this, I clean the excess metal out of the bore. Having the hone grind metal debris around the inside of the barrel is not a good idea.  Using the proper oil (as per instructions of the hone), I spend only enough time to remove any burs from the inside of the barrel.  Using a hone excessively can adversely affect the bore.  The final step is  to thoroughly clean the barrel. I find hot water helps remove honing oil. After that the barrel is ready to test.