One of the easiest ways to improve the accuracy of your paintball gun is to buy a new paintball barrel.
Not all paintball barrels are the same though, so you’ll have to do your research to ensure you choose the best paintball barrel possible for your needs and budget.
To help you with this research process, I’ve gone ahead and reviewed the top paintball barrels and chose the seven that I believe to be the best of the best.
Not sure what type, size, or length of paintball barrel to buy?
All the information you need to know regarding length, size, material, and everything else you could want to know about paintball barrels is answered towards the bottom of the page.
So without further ado, let’s get onto the reviews.
Best Paintball Barrels
Listed below are seven of the best paintball barrels currently available on the market today.
If none of these seven paintball barrels match what you’re looking for, then you can also check out my list of top runner-ups further down the page (right after the reviews).
I’m sure you can find at least one paintball barrel that fits your needs.
DeadlyWind Fibur X8 (Quietest)
If you want a paintball barrel that’s lightweight, accurate, and extremely quiet then you can’t go wrong with the DeadlyWind Fibur X8
The DeadlyWind Fibur X8 (XL 8-inch) is the only carbon fiber barrel on the market that uses the GoG 8-inch Freak XL inserts. Then there’s also the original DeadlyWind Fibur-X carbon fiber barrel that uses the 5-inch Freak Inserts. Since the X8 barrel uses the longer control bore 8-inch Freak XL insert, it’s supposedly shoots more accurately than the shorter control bore 5-inch inserts.
One of the big features that I love about the Fibur X8 is that it comes in three separate pieces — a threaded adaptor, a Freak XL 8” insert, and the main carbon fiber barrel. The advantage of this design is that it allows you to use the Fibur X8 on almost any paintball gun you wish by simply changing the threaded adaptor.
Another great feature of the Fibur X8 is its premium 3-layer carbon fiber material that’s truly in a league of its own. As stated on DeadlyWind.com, the Fibur X8 is made with “2×2 satin Twill external, uni-direction fibers laid up in a strong multi-vector pattern (whew that’s a mouthful) and a super slick Silkfiber inside that can be safely swabbed”.
The Fibur X8 also comes with a variety of different porting options such as:
- Normal Porting
- Double Porting
- Spiral Porting
- Double Spiral Porting
- No Porting (Rain Tip)
A quick warning though, many players have noted that they had a difficult time removing the reverse thread adapter when they first purchased the Fibur X8. Fortunately, there is a small hole on both sides of the threaded adapter that you can fit a small allen wrench through to give you leverage to twist off the threaded adapter.
- Size: 8.5, 10, 12, 14, 15, 16, 18, 20, 22, and 24 Inches
- Thread: Autococker, Ion, A5, 98C, Phantom, Kingman, Shocker, and More
- Bore Size Inserts: .679, .684, .689
- Porting: None, Normal, Double, Spiral, Double Spiral
Smart Parts Freak XL Barrel Kit (Most Popular Barrel Kit)
Originally made by Smart Parts (now GoG), the Freak XL is possibly the most famous paintball barrel kit of all time.
This popular paintball barrel kit was made as an improvement over its predecessor — the original Freak barrel system. What makes the Freak XL better than the original Freak barrel system is an extra 3 inches of length, a faster threading system (for both the front and back barrel), and better design in the looks department (at least in my opinion).
While the faster threading system makes it easier to remove the barrel for cleaning or maintenance when needed, the extra 3 inches of length is what improves the performance of the Freak XL by lengthening the control bore.
The control bore is the part of the barrel that “controls” the paintball. And since testing has shown that the best control bore length is somewhere between 7-9 inches (depending on your marker), GoG decided to make the Freak XL 8 inches in length. This longer control bore (compared to the original Freak) results in greater efficiency, a reduced sound signature, and lower operating pressure.
Now, this doesn’t mean that the original Freak barrel system isn’t a good paintball barrel by any means, just that the Freak XL is a little bit better. And I mean just a little bit.
Another feature I’m a huge fan of on both the Freak and the Freak XL is that it comes with a total of eight color-coded (or stainless steel) barrel inserts (.679, .682, .684, .687, .689, .691, .693, and .695) and two different porting options (Freak XL Linear Porting & All American Spiral Porting).
To top it all off both the Freak and the Freak XL come with a cool carbon fiber case that many players (including myself) seem to love.
- Size: 14 & 16 Inches
- Thread: Autococker, Ion, Tippmann A5, Tippmann 98C,
- Bore Size Inserts: .679, .682, .684, .687, .689, .691, .693, .695
- Porting: All American Spiral Porting and Freak XL Linear Porting
- Colors: White, Pewter, Pink, Red, Purple, Blue, Teal, Lime
- Insert Material: Aluminum & Stainless Steel
HK Army Threaded Lazr Barrel Kit
HK Army is one of the fastest-growing paintball companies at the moment and for good reason too, they know how to build quality products that players seem to love.
And while HK Army released a paintball barrel before, it just didn’t seem to take off for some reason or another. Their new Lazr barrel kit, however, has proven to be highly popular (especially in the speedball crowd from what I’ve noticed) amongst paintball players as of lately.
I think players are just happy to have a barrel kit option with eight control bores (other than the Freak, Freak Jr, and Freak XL) to be able to choose from. The Lazr barrel kit also comes with a lot of impressive features from other high-end paintball barrel kits such as the Planet Eclipse Shaft FL style back and rubber grips, the Freak XL style inserts, and the Infamous Silencio style porting.
HK Army has stated that their Lazr barrel kit is “the quietest barrel on the market”. While I’m not sure if their statement is true or not, I will say that the Lazr is at least one of the quieter paintball barrels currently available. Plus, the combination of the two styles of porting (dots and lines) looks pretty awesome, so it has that going for it as well.
My favorite feature about the HK Army Lazr barrel kit, however, is that it comes with an aluminum ball sizer. This ball sizer allows you to determine the average bore size of your paintballs so you can get the best accuracy possible out of your Lazr barrel kit.
Now I will admit that the Lazr paintball barrel is a little bit on the heavy side, but if you’re using the Lazr barrel kit on a lightweight speedball marker then the extra weight can be useful for reducing the recoil of your marker and thereby increasing your overall accuracy when shooting in rapid succession.
The HK Army Lazr barrel kit only comes in one length (15 inches), but it does come with four removable color barrel back grips (red, blue, black, and grey) and you can also choose between many different color options such as dust red, dust blue, dust purple, dust silver, dust pewter, dust gold, dust neon green, dust black, gloss black, and dust black with Boom Treatment.
All of the paintball barrel color options listed above can also be purchased with either black inserts or color-coded inserts, depending on what you prefer.
- Size: 15 Inches
- Thread: Autococker
- Bore Size: .678, .680, .682, .684, .686, .688, .690, .692
- Barrel Color: Dust Red, Dust Blue, Dust Purple, Dust Silver, Dust Pewter, Dust Gold, Dust Neon Green, Dust Black, Gloss Black, Dust Black w/ Boom Treatment
- Insert Color: Black & Color Coded
Carmatech Engineering Nemesis Rifled (Best for First Strike)
The best paintball barrel for magfed players like myself who love to shoot First Strike rounds is the Carmatech Engineering Nemesis Rifled Barrel.
With this rifled paintball barrel, you’ll have the best accuracy on the paintball field (unless another player also has a Nemesis) as long as you’re shooting First Strike rounds. And trust me, this rifled barrel is by far the most accurate paintball barrel that I’ve ever shot in all of my years of playing paintball.
So what exactly makes the Carmatech Nemesis such an accurate paintball barrel?
For starters, the Nemesis rifled barrel comes with a unique patent-pending “Spline Drive” Rifling System and a True Flight Muzzle Design. These patented features are responsible for making this paintball barrel highly efficient (supposedly 30% higher than some of the other rifled paintball barrels) and increasing its projectile muzzle RPM to 12,000 RPM.
This higher RPM further stabilizes the First Strike round while it’s in the air to help improve the accuracy of the Carmatech Nemesis just a little bit more. And to further improve the accuracy of the Nemesis paintball barrel, Carmatech Engineering came out with the NIPS (yes that’s the actual name) barrel tip and even a NIPS four-piece kit to help provide a better bore match for First Strike rounds.
By providing a better bore match, the NIPS (Nemesis Interlocking Projectile System) barrel tip helps to stabilize the First Strike round post-rifling by eliminating down range nutation, otherwise known as “corkscrewing”. Corkscrewing is essentially when the front end of the First Strike round moves in a small circular motion as it travels through the air, kind of similar to the shape of a corkscrew (the screw part not the handle).
Here are the bore sizes of the NIPS barrel tips: .685, .689, .693.
Now would I recommend you purchase the NIPS four-piece kit?
No, probably not…
Fortunately, the Nemesis barrel now comes stock with a NIPS barrel tip and that seems to work well enough for me. However, if you have more money than you know what to do with then sure, go ahead and get yourself a NIPS kit if you truly want to achieve the best accuracy possible when shooting First Strike rounds.
- Size: 9, 11, 13, 15 and 17 Inches
- Thread: Autococker & Tippmann A5
- Bore Size: .681, .686, .691
Custom Products Classic (Best For the Money)
If you’re looking for an affordable one-piece paintball barrel then you’re unlikely to find a better option than the Custom Products Classic (more commonly known as the CP barrel). This trusty aluminum paintball barrel has been around forever now and for good reason too, they simply work!
And no matter what type of paintball gun you’re using or particular color you’re after, you should have no problem finding a CP barrel that matches exactly what you want. With a total of 8 color options, 2 finish options (gloss & dust), 4 length options (10, 12, 14, and 16 inches), and 5 barrel thread options (A5, 98, Spyder, AC, Luxe), it’s hard to imagine that wouldn’t be the case.
The CP Classic isn’t just some cheap paintball barrel made for beginners either. Even though it only costs thirty dollars, the CP Classic paintball barrel is diamond honed, hand-polished, and true to size (unlike some other cheap paintball barrels on the market).
In fact, you could easily use the CP Classic barrel in a tournament setting and nobody would have a clue that you weren’t using some high-end barrel kit (as long as the paint matches the bore of your barrel) such as the GoG Freak XL or HK Army Lazr.
And in all honesty, I sometimes feel as if the longer control bore of a one-piece barrel helps it perform better than most two-piece barrels. Of course, this is only true if your paintballs properly match the bore of your barrel.
Now, I will admit that I’m not a huge fan of the red CP logo on every barrel. As a woodsball player, the red logo doesn’t match that well with the rest of my camouflage-painted paintball marker. However, if you do have a paintball marker with red somewhere on it (or if you’re not an OCD freak like me) then the red logo should be no problem.
The only other feature that I would like to mention about the CP classic Paintball Barrel is that it doesn’t have a lot of porting so its sound signature is a little bit on the louder side. not that it’s overly loud or anything, but it may be just a tiny bit louder than most of the other paintball barrels on the market that have lots of porting.
- Size: 14 & 16 Inches
- Thread: Autococker, Tippmann A5, Tippmann 98C
- Bore Size: .685, .689, .693
Lapco Bigshot Assault (Best for Milsim & Magfed)
Now it’s time to review the coolest looking paintball barrel on the list — the Lapco Bigshot Assault.
The Lapco Bigshot Assault is actually a modified version of the regular Lapco Bigshot, except the Assault has additional porting and a threaded muzzle tip. The additional porting helps to reduce the sound signature of your paintball gun and the threaded muzzle tip gives you the ability to mount Lapco barrel tips, Hammerhead barrel tips, Lapco Apex Adapters (to attach the Apex or Apex II), and more!
Another great feature of the Bigshot Assault is that it’s made from a high-grade aluminum that’s custom formulated by Lapco to meet military standards. To further entice Milsim players to purchase the Bigshot Assault, the outside of the barrel is bead blasted to provide a micro-rough, non-reflective surface, and then anodized with a deep penetration finish.
That’s not all either.
Both the bore size and barrel wall thickness are concentrated and consistent to eliminate the visible wavy lines that you’ll often find on lower-quality paintball barrels. The Bigshot Assault also goes through a 3 step micro-honing process to create a mirror-inside finish.
This micro-honed finish is stiff arbor honed (whatever that means) by a master craftsman and supposedly performs better at self-cleaning and is more gas efficient than the majority of the paintball barrels on the market.
All of these impressive features listed above are why (in my opinion) the Lapco Bigshot Assault is by far the best paintball barrel for magfed (how do magfed paintball markers work) players and Milsim enthusiasts who want a realistic-looking barrel that not only looks bada**, but performs great as well. The Bigshot Assault (and regular Bigshot) are both made 100% in-house in the U.S.A. and come with “The Legendary LAPCO Lifetime Warranty”.
- Size: 10, 14, & 16 Inches
- Thread: Autococker, Tippmann A5, Tippmann 98C, Spyder
- Bore Size: .684, .687, .690
How to Choose a Paintball Barrel
Choosing which paintball barrel to purchase is never an easy task.
With so many different brands, models, lengths, bore sizes, types of materials, and other features you have to worry about (such as one-piece vs two-piece and rifling vs no rifling), it’s easy to make a mistake and choose the wrong one.
Fortunately, by following the advice I’ve listed below you should have no problem choosing the best paintball barrel to fit your needs and budget.
So without further ado, let’s begin!
When buying a paintball barrel the first thing you need to do is figure out what kind of threading your paintball gun uses.
Here are the most popular types of barrel threading available:
- 98 Custom
Here are some of the least popular types of barrel threading available:
- Automag twist lock
- Tiberius Arms twist lock
- Angel A1
- Angel G7
If you somehow manage to buy a barrel with the wrong kind of threading, then you’ll either have to buy an adapter to convert the barrel you bought to the threading you need or you’ll have to buy a new barrel entirely.
The adapter is by far the cheaper option, but then you have an extra piece on your paintball gun that doesn’t necessarily need to be there. Even though it probably doesn’t weigh much at all, this is something to think about.
Here’s a helpful chart from Hammerhead Paintball showing you the different types of barrel threads available and what kinds of paintball guns use them.
Another major factor to take into consideration when buying a paintball barrel is what type of material do you want your barrel to be made out of?
The most common material that paintball barrels are made from is aluminum, with the next being stainless steel, carbon fiber, and then brass. However, even though aluminum may be the most commonly used material for paintball barrels, this doesn’t mean it’s the best material by any means.
Okay, so I know you’re probably thinking, “what’s the best material for a paintball barrel?”.
While I would like to say the answer is stainless steel, or carbon fiber, or even brass, I honestly can’t say for certain which is the best material for constructing a paintball barrel. Every single material has some kind of advantage over the other materials so it’s really up to your personal preference which one you want to choose.
Let’s start with the advantages and disadvantages of stainless steel.
To begin with, stainless steel is much heavier than aluminum (which is heavier than carbon fiber), but not quite as heavy as brass. However, because stainless steel is a much harder metal than aluminum, it’s also much more durable and less likely to get dinged up in your gear bag. Plus, the extra weight helps to reduce the amount of recoil felt in the barrel when shooting in rapid succession. This can help lead to a slight increase in overall accuracy.
Supposedly there’s also some science that states the honing inside of a stainless steel barrel should have a slightly lower coefficient of friction than other materials and therefore should be more accurate, but even if this is true it’s such a minuscule difference that I wouldn’t worry about it
There’s a reason aluminum is the most common material used for paintball barrels, it’s lightweight, it can be anodized (a nice type of paint), and it works exceptionally well. Plus it’s cheap to manufacture.
Of course, if you drop an aluminum barrel on the ground or bang it up against something hard it may get scratched up a little bit, but is a slight scuff mark really that big of a deal? At least it’s not as soft of a metal as brass that requires constant maintenance to keep looking presentable.
If you want the lightest paintball barrel possible then you’re going to want to get a barrel that’s made from carbon fiber.
Besides being extremely lightweight, most modern carbon fiber paintball barrels are known to be quiet, highly durable, and built to last. This is good news as you won’t have to worry about anything coming unraveled because you bumped into a rock or something.
Now, there were some quality issues with some carbon fiber barrels in the past, but fortunately, none of those barrels are still in production.
Having such a lightweight barrel does have its own set of pros and cons though, the main pro being that it greatly reduces the overall weight of your paintball marker. This makes it easier for you to maneuver the front-end of your paintball gun which can prove to be useful sometimes (such as when you’re snap shooting).
However, the lighter the barrel is the more your accuracy will be affected by recoil. Now, a little bit of recoil isn’t going to ruin your accuracy by any means, but every little bit of variation in the position of the barrel is going to negatively impact your overall accuracy. Moving the end of your barrel just an inch can result in a difference in yards downrange.
The least popular type of material used to make paintball barrels would have to be brass.
Now, this doesn’t mean that brass is a bad material for making paintball barrels, as it’s actually been proven that brass performs better than most other materials.
In fact, in a test done by Mann on Pbnation.com, the PPS brass barrel with double porting was proven to be the quietest paintball barrel out of some 25+ barrels that were tested. And while the PPS brass barrel might not have been the most accurate paintball barrel in Mann’s testing, it still performed exceptionally well and might have done even better if there were more bore options from PPS to better match the paint.
So what are the downsides of using brass?
Well, for starters, brass is prone to scratches (similar to aluminum) and is by far the heaviest material used to make paintball barrels. Brass is also known to corrode over time (if not properly taken care) of so you’ll have to put more effort into cleaning your barrel than you would with any of the other materials.
Palmers Pursuit Shop recommends that you simply wash off their barrels with hot water and dry it off afterward to avoid corrosion.
When I first started to play paintball I always assumed that a longer barrel could shoot a further distance than a short barrel. Of course, I now know this isn’t true, but at the time I was convinced that I needed a long paintball barrel so I could become a paintball sniper.
So what exactly do paintball barrels do and what’s the best paintball barrel length?
Paintball barrels are solely responsible for guiding the paintball in the right direction and studies have shown but it only requires around seven to nine inches in length to achieve optimal accuracy. Anything after seven to nine inches only helps to further reduce the sound signature of the paintball marker when fired.
The best paintball barrel length is anywhere between 12 and 16 inches long. A 12-inch barrel is better suited for front players and CQC (close quarter combat) players as it’s better for snap shooting and maneuvering through doors, hallways, etc. Whereas a paintball barrel that’s 14-16 inches in length is better suited for mid-back players as you can press the barrel into the side of inflatables to help you maintain hidden while still being able to fire upon your opponent.
Longer-length barrels (14-16 inches) are popular amongst woodsball and scenario players as well as they’re quieter and better in situations when you’re trying to clear vegetation out your way.
Choosing the proper bore size for your paintball barrel is the most important factor in determining your overall accuracy, efficiency, and how often you experience barrel breaks. The bore size of a paintball barrel is simply the inside diameter of the barrel.
So what’s the best paintball barrel bore size?
This depends on what size of paintball you’re using. Unfortunately, the size of a paintball can vary depending on which manufacturer made it, how it was made, the quality of the paintballs, and what type of weather or climate it’s been stored in.
Due to the wide variation of paintball bore sizes, many players opt to purchase a paintball barrel kit with a wide variety of bore size options (such as the Freak XL with eight bore size inserts) to choose from. The majority of players, however, would rather save some money and purchase a one-piece paintball barrel. The downside of doing so, of course, is that you will only have one bore size to choose from.
So, which bore size should you choose if you want to achieve the best accuracy possible?
The best paintball barrel bore size is somewhere around .685 as that’s the most common paintball size in this current day and age. You can tell if your paintballs match the bore size of your barrel by simply dropping a paintball down the barrel (or insert) and observing if it gets stuck or not.
If the paintball gets stuck in the barrel but you can blow it out with a small breath of air then the paintball matches the bore size of your barrel. However, if the paintball easily falls through, or if it’s too big that it gets stuck, then the paintball doesn’t match the bore size of your barrel.
One-Piece vs Two-Piece
Most paintball players are under the impression that two-piece barrels (or barrel kits) are always better than one-piece (regular) paintball barrels, but this isn’t always the case.
One-piece paintball barrels are slightly more efficient than a two-piece paintball barrel because the one-piece has the same control bore all the way through, whereas a two-piece gets wider (typically from .68 – .700) after the control bore (1st half) of the barrel.
This difference in efficiency is more than likely negligible, so in all honesty, it won’t make a difference if you choose a one-piece or a two-piece paintball barrel. Unless that two-piece paintball barrel has a control bore that’s less than seven to nine inches in length.
Since recent testing has shown that somewhere between seven to nine inches is the best control bore length, anything less is going to result in a loss of accuracy and efficiency. How big is this loss? More than likely it won’t make a huge difference, but there’s a reason why paintball companies have begun to manufacture their barrel kits with a longer control bore.
While many players love to argue that barrels have little effect on accuracy (as long as the paint properly matches the bore), there’s no denying that upgrading your barrel can affect the sound signature of your marker.
The best way to reduce the sound signature of your paintball marker is to upgrade your barrel to one with more porting. You can also reduce the sound signature of your marker by using a longer barrel, but length is only going to help so much.
Porting > length for reducing sound signature.
Closed-Bolt vs Open-Bolt
This may not be a major problem anymore, but in the early days of paintball players would often have to find out if their paintball gun was open bolt or closed bolt as this would determine if they needed a paintball barrel that was under bored or not.
So what’s the difference between an open bolt and a closed bolt paintball gun?
A closed bolt paintball gun is any marker where the bolt remains in the “closed” position (also known as the forward position) with the paintball resting in the barrel until the marker is fired. Once fired, the bolt will then open and HPA or Co2 will propel the paintball forward allowing another paintball to fall into the barrel with the bolt closing behind it.
An open bolt paintball gun is any marker where the bolt remains in the “open” position (also known as the back position) with the paintball resting in the breach until the marker is fired. Once fired, the bolt will then push forward (closing the bolt) and HPA or Co2 will propel the paintball forward. After the paintball is propelled out of the marker the bolt will then return to the open position, allowing another paintball to fall into the breach.
The reason you need to underbore when using a closed bolt paintball gun (typically a pump paintball gun or an Autococker) is because the bolt is closed behind the paintball that’s about to be fired, forcing the paintball to rest in the barrel (not in the breach) where it can easily roll out of your paintball gun. However, if you underbore (use paintballs that are bigger than the bore size of your barrel) then you won’t have to worry about barrel rollout.
This is not a problem with open bolt paintball guns.
Frequently Asked Questions
Here below are some of the most frequently asked questions related to the topic of paintball barrels. If you don’t find the question you want to be answered below then leave a comment at the bottom of the page and I’ll answer it as soon as I can.
What Is the Quietest Paintball Barrel?
The only testing done on the noise level of paintball barrels was the testing done by Mann on Pbnation.com that found the PPS double ported brass barrel to be the quietest paintball barrel out of the 25 + barrels that he tested.
Unfortunately, this test was done in 2004 so most of the paintball barrels that were tested aren’t even available to be purchased anymore. That’s why I’ve decided to simply make a list of the quietest paintball barrels on the market today to give you a few different options to choose from.
Here are those paintball barrels below:
- Planet Eclipse Shaft FL
- Infamous Silencio Shaft FL
- Stella – Inception Designs
- Lurker EigenBarrel V4
- Dye UL-S
- DeadlyWind Fibur X8
- HK Army Lazr
All of the paintball barrels listed above are extremely quiet and every single one of them would have easily made this list of best paintball barrels.
Do Paintball Barrels Make a Difference?
Upgrading your paintball barrel can make a huge difference in your overall accuracy and sound signature if you’re using an entry-level marker with a lousy stock barrel. However, if you’re equipped with a mid-range to high-end paintball gun then the stock barrel that comes with your marker is more than likely high (or at least good) quality, and upgrading it to an aftermarket paintball barrel may not make that big of a difference in performance.
Here’s a video from the legend himself, Tom Kaye, discussing the advantages of upgrading to an aftermarket barrel. What he has to say may surprise you. (go to 14:38)
Underboring vs Overboring?
While most players prefer to match their paintballs to the bore size of their barrel, some players would rather choose to underbore or overbore their paintball barrel as they believe it’s the best way to get the maximum performance from their paintball gun.
So what exactly is underboring and overboring?
Underboring is when the bore size of your paintball barrel is smaller than the bore size of your paintballs. Whereas overboring is when the bore size of your paintball barrel is larger than the bore size of your paintballs.
You’ll find some players that swear you can improve your accuracy and efficiency by underboring your paintball barrel, while other players will swear that overboring is best for accuracy, even though it may come at the cost of some efficiency.
You can tell if your paintball barrel is underbored or overbored by dropping a paintball down the barrel (or insert) and seeing what happens. As said before, if you drop a paintball down the barrel and it gets stuck, but yet it can be blown out with a small breath of air, then the paintball matches the bore size of the barrel. This is known as a paint-to-bore match.
However, if the paintball falls straight through the barrel without stopping then the paintball is overbored. Whereas if the paintball gets stuck in the barrel and you have to blow (or push) hard to get it out, then the paintball is underbored.
I recommend trying overboring, underboring, and matching your paint to your barrel to see what works best for you. Unless you have a closed bolt paintball gun such as a Tippmann SL-68 II, CCI Phantom, or WGP Autococker, then you’ll want to underbore to avoid barrel rollout.