straight rifled barrels

How does the new rap4 straight rifled barrel compare to the A-5 flatline.

I have some people who swear by the rifled barrels. They say it does get a lot of distance with accuracy. I guess it is just one of those things you have to try it to believe it.

kickinwing2010 wrote: Actually if you look back to the black powder days they began to increase accuracy by rifleing there barrels so I would have to imagin if it worked with a metal ball it will for with a paintball, considering the paint to bore match is perfect.

This discussion could get involved. I own a Flatline (actually two), an Apex and a Hammerhead Pro. You are correct about the paint match to the bore. I used to be able to find paint that was large enough to touch the bore (.693"). With any paint and the correct sized back (Hammerhead calls them Fins) the barrel was very accurate (8" groups at 120 ft). But when I found paint that actually fit the bore...have to push it the entire length of the bore...accuracy was as good as 3" groups at 120ft.

Accuracy is almost unbelievable with that kind of paint to bore match. I used to get into big-time arguments on pbnation with the opposition claiming that liquid filled paintballs could not be spun. Finally I prevailed by pointing out that if spinning a ball was impossible then a Flatline could not work either...but we all know it does. And I'll say definitively that a paintball coming out of a barrel that actually imparts axial spin has improved accuracy just like the Kentucky rifle improved the accuracy of the mini-ball.

But, I have not found that there is any appreciable change in air time and distance of a paintball coming out of a rifled barrel. And, I cannot find any paint that actually continuously specs .693"-.694" so the full accuracy potential is moot. I have found a couple of "off brand" that measured that large, but the second time I bought them, both sized smaller.

At the chance of being redundant, the Flatline and Apex barrels have both proved themselves on the field and on the test range. Both impart backspin which generates lift and dramatically extends the flight and effective range of the ball. Accuracy "appears" to suffer at extended range, but my tests show that that is directly related to the fact that air currents have a longer time to act on the ball at such long flight time.

The Apex is not as finicky as the Flatline is as to the kind and size of paint you run through it. I find the Apex slightly more accurate than the Flatline, but when the Flatline is carefully adjusted with a good paint selection it is hard to really find any difference.

I loved the Flatline. I prefer the Apex and I use the Hammerhead, even when using small paint, more than the Apex on the speedball field.

Now, what would "straight" rifling do for a paintball?

Edited by Bruce A. Frank - 23 January 2007 at 1:44pm

I've used several spiral ported barrels as well as an Armson that had internal "rifling".  I can tell you from personal experience, the rifling does NOTHING for accuracy ABSOLUTELY NOTHING for distance.  Best to find a good paint to barrel match, that will do more than anything...

I have seen several videos of tests on spiral ported barrels and they do not/can not impart spin.

Now all those fluid dynamicists may theorize on the ineffectiveness of spiral rifling on paintballs, but their theory falls apart when when you apply the same question about backspin.

Fact is few to none of the rifled barrels can actually impart axial spin to the paintball because the fit is not tight enough.

You can do your own test. Create a tight fit by cutting a small circular piece of tissue paper or paper napkin...or even a piece of "T" shirt material and use it to create a snug fit. Place the paper over the muzzle and push it into the bore of the rifled barrel with your finger tip to shape it. Pull it back out, place a paintball in the center and gently push it back down the bore with your finger tip. You now have essentially a "patched" ball (a black powder term) started down the bore. It should be a tight enough fit for you to feel resistance as the patched ball is pushed down the bore. Too tight and the ball may break when the marker is fired.

Use a bore fitting dowel to push the ball down the barrel until it rests against the end of the bolt. The ball will be spun by the rifling when it is fired. If you kept the patch small enough so that it doesn't wrap any further up the sides of the ball than is necessary to make a tight fit, when the ball is fired, the patch falls away just beyond the muzzle...so flight of the ball is not effected.

You may have to play with paper thickness and different ball sizes to get the needed fit. Good quality fresh paint is essential. You want uniform paint so there is no out-of-balance factor to skew the test.

Shoot twenty shots this way off of a bench rest with some kind of sight to assure repeatability of point of aim.

Then try the test with your good quality smooth bore with normal fitting paint.

My initial tests with the Hammerhead Pro was done this way and showed me that by getting a fit that assured axial spin, the barrel showed significantly better accuracy over a standard smooth bore.

Since "patching"each shot is certainly impossible during play, one would have to find a paint diameter that actually fit and touched the lans of the rifling on the full circumference of the ball.

RavenGuard wrote: *cough* paintballs are filled with liquid, which doesn't necessarily spin with the outer shell.  the effect may still be there, just likely too small to notice. also, a metal slug weighs more than a paintball, and the heavier a projectile the more accurate it will be at longer ranges.

So you are saying that my 243 caliber rifle cannot be as accurate as my 45-70? There is some accuracy retention due to weight of the projectile and its interaction with cross winds, but that is of little significance here. At extreme distance accuracy is reduced due to interaction with wind currents...just as with long distance travel of a paintball. Behavior of a bullet shot at a target 1000 yards away will have similar behavior over that distance as a paintball  does over a 200 foot distance.

If the THICK liquid core did not accelerate up to spin speed fairly well then neither the Flatline nor the Apex would work. Realize that the paintball in the Apex barrel goes from "0" rotation to fully functional backspin in less than 2 inches. So clearly the liquid core comes up to speed well enough to maintain the required backspin of the ball as it travels down field. That performance clearly indicates that the ball can be accelerated by rifling to its functional axial rotation in the length of a marker barrel. And the FACT is that I have done the tests as I described above and the axial spinning paintball is more accurate.

Edited by Bruce A. Frank - 23 January 2007 at 4:44pm

A lot has changed in 20 years!

if the same barrel type with same boar just smooth and rifled barrels have been tested side by side, and not shot freehand(clamped to a table), then this conversation is going no were.  
And it seems that paint is th only issue in this post, the only inconsistancy that makes peoples opinion differ. from shell diameter to shell thickness and the paints thickness inside. comparing to a bullet is not even logical.

I did shoot Hway's Apex barrel this past summer and I must admit I enjoyed it.

I really liked the flatline on my old 98 too. The A-5 flatline left me not so impressed.

If I were to buy a barrel that imparts spin...it would be the Apex. Cocker-threaded for my ETac (of course).

edit: LOL at above post.

Edited by Ken Majors - 26 January 2007 at 4:44pm

Fluting is carving the outside of the barrel down to reduce weight and help dissipate heat. Straight rifling means that instead of a spiraled groove(s) in the barrel, it is grooved in a straight line from front to back. I think the thing to remember about rifling a paintball barrel is that you will never achieve the accuracy that a Kentucky Long Rifle or any other black-powder rifle (or modern rifle) achieved due to mass, velocity, and the fact that the rifling in firearms actually CUTS into the projectile. While rifled barrels do achieve spin with paintballs, and can increase accuracy under controlled test conditions, the spin generated has a 'slip' effect as the ball cannot be forced to rotate in a tight spiral within the barrel without cutting the gelatin shell and causing the round to foul the barrel. This slipped spin (the ball rotates at a lesser degree than the rifling is supposed to achieve) doesn't produce enough spin on the round to keep the fill rotating at a fast enough speed to make the liquid act as if it were a solid in motion. The fact that paintballs are never filled to capacity also means that the fill (especially if thick) doesn't achieve full centrifugal force. Simply put, not all of the fill is forced to the outside of the round and held there by the rotation's energy due to the sluggish spin on the round. This can actually cause inaccuracy of the round by creating a sphere that is spinning in an off-balance manner.

That said, the reason barrels such as the flatline and the apex work as well as they do at garnering better distance is due to the fact that the spin induced on the round is back-spin. The fluid inside the shell doesn't even need to move with the round for them to achieve farther distance. The properties at work with a back-spun round and a rifle-spun round are completely different. The way both the flatline and apex work is by changing the air pressure above and below the round just like the leading edge of an airfoil. The back-spin on the round's shell causes the air to literally 'pile-up' underneath the round due to the friction of the rotating shell against air molecules. The resulting airfoil effect causes lift due to the fact that the air-pressure below the round is now higher than the air pressure above it.
A rifled round simply equalizes the air-pressure around the round and causes it to "slice" through the intervening air molecules more readily, giving it greater accuracy IF it has the mass AND spin to cause that kind of disturbance in the air and maintain it. Even the flatline's spin on a round can be negated by breezy days if the round has a tail wind.

The ONLY way to get a rifled paintball barrel to be more accurate would be to induce tighter spin on a higher mass with more stability to it's construction.