Here’s an interview I did with Matt of Kel-Tec on their new RFB product. My questions are in bold italic, and his answers are standard text. There seems to be a lot of interest in their RFB product, which is a bullpup .308 with a novel forward ejection system. Here’s Matt:
The .308 market is certainly less crowded than the .223 market, but Kel-Tec is still competing with some old standbys like the M1A, FAL, HK91, and the AR-10. How do you think the Kel-Tec RFB stacks up to these rifles?
The RFB is shorter, lighter, easier to produce, has a better trigger, and is more adaptable to modern accessories like optics and Picatinny devices. Those other designs could be considered Generation II Semi-Auto designs, the RFB is Generation III.
What made you decide to go with a Bullpup design?
All of these designs are reliable, but they are also over 40 inches long, and that includes some of the carbines. The only version of the RFB that will be that long will be the 32″ model which has only been produced as a prototype thus far. The 18″ model that is being produced now is only 26″ long, 27″ with the A2 style flash hider. That’s shorter than an M4 Carbine with the stock collapsed and comparable to an MP5 A2. That’s why we went with a Bullpup.
Most designers steer away from Bullpup designs because they blow gas back into the shooters face from the ejection port, but this is negated by our forward ejection system. There is also a superstition that if there is a catastrophic failure that the shooter is more likely to be seriously injured or killed if their face is closer to the action, but with the RFB, there are two layers of steel between the receiver and the shooter, so if there was a over pressure cartridge that had a case head separation, the pressure would travel downward through the magazine well, which is the path of least resistance. The shooter would likely be able to drive themselves to the hospital if they were injured at all.
Are you planning to release the RFB in other calibers, like .223 Remington?
Seeing as the intermediate caliber market is almost completely saturated and has more than a couple Bullpup designs, we feel it would be better to focus on the full powered cartridge market first. The first RFBs are of course in 7.62 NATO, but future variants will be chambered in the offshoots of the .308 cartridge case, such as the .260 Remington, 7mm-08, .243 Winchester, .22-250, and so forth. If it has the same sized rim and feeds from a metric FAL magazine, it may be chambered in the RFB. Obviously, we will choose which cartridges we offer based on demand, but since the barrel on the RFB can be easily changed with our Armorer’s kit, we may offer these calibers in accessory barrels even if we never build them in rifles.
What kind of accuracy can you expect from an RFB?
The RFB is an exceptionally accurate design due to its excellent trigger and wonderfully short lock time. I’ve shot Sub MOA with every RFB variant, including the 18″ model. The biggest detriment to accuracy is ammunition quality. American made bulk ammo will usually give you between 1.5-4″ groups depending on the brand, with copper jackets giving better results than steel jackets. I’ve fired some Portuguese, Indian, and Mexican Surplus 7.62 Ammo that gave horrible accuracy. Generally, if you get over 2″ with an RFB using match ammo, it probably isn’t the rifle.
Lock time is the time in between when the sear releases the hammer or striker in a firearm and the firing pin contacts the primer. Lock time is one of the most important aspects to accuracy in a rifle. It’s difficult to test, so most manufacturers don’t bother too, since few people know what it is.
Most semi autos use a hammer that has enough mass to ignite the most stubborn of military primers reliably, this is their only mission. The heavy, slow, and often long travel of the hammer after sear release allows the rifle to move a nearly imperceptible amount in the shooters hands, causing an ever more dramatically increasing error the further out the target is. Bolt Actions have inherently less mass and a shorter travel between the end of the striker and the primer, resulting in a naturally short lock time, usually around 3 Milliseconds for modern actions. This is why bolt actions are preferred for use in Competition rifles. This is also why open bolt GPMGs are not used as Sniper Rifles.
The RFB has a lock time of about 4.5 Milliseconds, which is better than many WWII bolt actions and nearly every factory semi-auto ever built. The AR-15 is considered very accurate for a semi-auto, and it has an average lock time of about 9.5 Milliseconds.
The trigger is usually the Achilles heel on Bullpup designs. I understand you’ve made the trigger on the RFB considerably better than other Bullpup rifles. Can you speak to that?
Most Bullpups are simply conventional rifles with their trigger groups put in the wrong place. Witness various Kalashnikov Bullpup conversions. The RFB was designed from the ground up to be a Bullpup, and it has never been anything else. The difference between the RFB and most Bullpups is the lack of linkages between the trigger and the sear trip. The trigger is squeezed, and it moves the sear trip directly, as on a conventional rifle. The sear trip actuates the sear which releases a spring loaded linkage which is attached to the hammer, similar to a Browning High Power. The springs which are attached to the linkage pull the hammer which moves up to strike the firing pin.
The RFB also has a very wide trigger, which increases the surface area on the shooter’s finger and gives the sensation of having a lighter pull than it does. The 18″ models have a trigger that is calibrated to be between 4.5-7.5 pounds for legal reasons. Very early production rifles had triggers that were slightly above that specification, but nobody has complained yet. The standard RFB comes with optimized components that are non-adjustable, but these can be replaced with adjustable components if the customer desires. The RFB was designed to include mechanisms to adjust the take up, over travel, and trigger spring pressure. The sear spring can also be adjusted, but most shooters will not be able to detect a difference in this adjustment. Everyone who’s handled the RFB has commented on how good the trigger is, and we feel that most people won’t feel the need to install the adjustable components, so those will be offered on later models as an option. This will help ease production so that as many rifles can get built as possible.
One concern I’ve heard from folks is the reliability of the ejection system, with fears that could get jammed up, and malfunction. How reliable have you found it to be in testing?
The RFB is essentially the first semi-auto rifle to have a controlled round extraction system. It uses two extractors to pull the fired case out of the chamber by way of the carrier and gas system. It has proven to be very reliable in testing. Once the fired cases are in the ejection chute, they have no where to go except forward. They have no surface to stick on which could cause enough friction to jam the action, no matter how much dirt got into the ejection chute area. Everything is moved forward by the reward inertia of the weapon firing, which gives a kind of natural ejection force to the cases in the chute. Tubular magazines don’t jam unless they get dented, and the ejection chute on the RFB is inside of the rifle, making it nearly impossible to damage while carrying or shooting the rifle. The RFB is quite possibly the only rifle ever built that will never stove pipe.
