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Author Topic: Accuracy of the Kel-Tec RFB  (Read 1892 times)
pkruchowski
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« on: December 30, 2016, 12:59:51 AM »

Can someone tell me the accuracy of the RFB? It looks like an awesome rifle.
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HBeretta
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« Reply #1 on: December 30, 2016, 04:15:04 AM »

null
« Last Edit: December 31, 2016, 01:00:12 AM by HBeretta » Logged
Ronmar
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« Reply #2 on: December 31, 2016, 12:09:17 AM »

RFB...

Minute of bad guy:)

Joking aside, most groupings I have seen people post about are sub 2MOA(<2" @ 100YD). This has also been my experience with mine.  Sadly, the RFB's biggest failing I think was KT's decision to machine the chamber to a very generously throated 7.62 machine-gun spec, instead of a SAMI .308 spec.  It is this detail I believe that is behind the RFB's accuracy.  Basically the bullet has to jump a small gap when fired, to engage the rifling.  The case neck shifting a little during the explosion in the case makes for an inconsistent bullet launch and resulting wobble in flight.  The fact that I and many others seem to get our best groupings with steel cased ammunition supports this theory IMO(stiffer case neck).  $10 a box 147 grain Tula from wallmart delivers my best groupings at around 1.5"(maybe a little less:)) pretty consistently out of my RFB.  That being said, it is afterall a carbine and NOT a precision rifle, and IMO is plenty accurate for anything you might ask a carbine to perform.  It probably could have been sub MOA with a better chamber and optimized load though:( 

It is a good thing it likes the cheap stuff, because this thing really likes to be shot:)

With the gas adjusted properly, It is a 7.62 with recoil closer to a 5.56.  It has an outstanding trigger for a bullpup which is my way of saying it has a trigger much like any other rifle you have ever fired. What KT did was keep the sear at the trigger where it belongs, and remoted the hammer. So the trigger takup and break is like most other normal triggers.  Most other bullpups remote the trigger from the sear and hammer which makes them mushy and somewhat unpredictable. 

The balance is fantastic!  That and the low recoil lead me to label this rifle the "ultimate girlie gun"  It is so cool to watch everyone stop shooting and stare when My 5'7 wife steps up to the line and lets go with 20 rounds rapid fire:)

I like mine...     
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flylo
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« Reply #3 on: January 22, 2017, 01:22:35 PM »

If you hand load why can't you just neck size & set the bullet out farther? The great part & art of hand loading.
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TNC
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« Reply #4 on: January 22, 2017, 05:14:41 PM »

If you hand load why can't you just neck size & set the bullet out farther? The great part & art of hand loading.

I'm thinking the cartridge/magazine length may become a problem.  The RFB's throat is what's long.  The bolt face to chamber length is probably "normal".  The longer throat makes the bullet jump to the lands.  The bolt rifle practice of setting bullets higher in the case can often run into a problem with a magazine fed semiauto...and even some magazine fed bolt guns.  But...I'm not sure I've read of anyone over on the Kel-Tec forum mentioning serious reloading efforts with the RFB while employing the higher bullet placement in the case...maybe because it's just too far to the lands.

ronmar...I'm guessing your and/or others have used something like a Hornady OAL guage or such to find that long throat?
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flylo
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« Reply #5 on: January 22, 2017, 05:52:17 PM »

What's the large thread for where the barrel meets the body?
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Ronmar
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« Reply #6 on: January 22, 2017, 07:23:55 PM »

If you hand load why can't you just neck size & set the bullet out farther? The great part & art of hand loading.

Yep, TNC summed it up.  The bullets cannot be extended any farther and still fit into the magazine.  I did some experiments with lengtherned bullets that I had to load into the chamber by hand individually.  They did appear to perform better but it was under less than favorable range conditions so I never took any group measurements.

As for measuring the throat length, I have seen someone take a wax casting. Those pics were posted over on the KTOG site qute a while back. A couple different companies make gauges to measure this. Myself personally, I loaded a bullet really long in an empty case and very lightly crimped it. I measured it's overall length, lightly lubed the bullet with case lube and gently chambered and removed it. I then measured it's OAL to detect any movement after chambering.  I actually had to do this several times as initially I wasn't seating the bullet long enough to see any movement when chambered as I never envisioned it had as long a throat as it does...  Eventually I loaded one long enough to see that it was compressed when chambered.  I then recreated the test a few times to confirm the measurement. About 1/10 of an inch if i recall(freakin huge:)) 

The large thread at the barrel to body(receiver?) connection is how the barrel is attached to the receiver and I am assuming how headspace is set...
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flylo
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« Reply #7 on: January 22, 2017, 08:12:31 PM »

Can the barrel be set back or does anyone make a barrel for it to cut a tighter chamber & shorter throat? Sorry to beat a dead horse but I just paid $255 for a 308 T/C Compass with a 1 moa guarantee & it will shoot 1/2 that with good ammo. I just like rifles as accurate as they can be. Thanks for all the great info!
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TNC
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« Reply #8 on: January 22, 2017, 08:50:19 PM »

Can the barrel be set back or does anyone make a barrel for it to cut a tighter chamber & shorter throat? Sorry to beat a dead horse but I just paid $255 for a 308 T/C Compass with a 1 moa guarantee & it will shoot 1/2 that with good ammo. I just like rifles as accurate as they can be. Thanks for all the great info!

Due to the RFB being somewhat unique, I don't think you'll find a reasonable way to set the barrel back in the action or shorten the throat.  Now...I guess with enough money and a talented gunsmith...something could be possible...but probably not logical.  Chambers can sometimes be modified by reaming, but the problem here is that the "hole" is already too long, so that is not a likely solution.

It's not "generally" fair to compare bolt rifles to semiautos as far as accuracy is concerned, and IMO bullpups are even less accurate, mainly from an ergonomic standpoint.  However, I notice on the Kel-Tec forum that 24" Hunter model RFB's get used for hunting and such with apparently decent results...but I know nothing about the 24" model from personal use.  My 18" RFB is more than adequate for what I expected from it.  I put it in a similar performance category to my 16" Armalite AR10 .308 carbine. 
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Ronmar
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« Reply #9 on: January 22, 2017, 10:20:45 PM »

Can the barrel be set back or does anyone make a barrel for it to cut a tighter chamber & shorter throat? Sorry to beat a dead horse but I just paid $255 for a 308 T/C Compass with a 1 moa guarantee & it will shoot 1/2 that with good ammo. I just like rifles as accurate as they can be. Thanks for all the great info!

Yes it could be done, but that would require some specialized/custom tools just to disassemble it.  You would have to be able to set the barrel back at least 1/10 of an inch. Then trim that much from the chamber and re-ream the chamber.  All pretty advanced machine work.  The barrel to receiver connection uses a unique attachment method, that may not be possible to re-torque without the addition of a consumeable component only available from KT, or at the very least more custom work to fabricate.  Shortening the barrel also re-positions the gas port and since the barrel is the "frame" of this rifle, it would also re-position the gas block and forward sight attach point. This of course efects the gas-piston to carrier interface, ejection chute ECT...  IE: It pretty quickly goes from a chamber trim to a cascade of design issues and compromises.  The easiest way I can see is to convince KT to offer an upgrade SAMI .308 spec barrel as a replacement...  Second easiest would be to find a master gunsmith/machinist to take on engineering a new barrel from a 30 cal bull barrel blank.
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flylo
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« Reply #10 on: January 23, 2017, 12:27:58 PM »

Mine comes in this week, can't wait to try it out
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Steelviper
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« Reply #11 on: February 04, 2017, 12:49:36 PM »

Yes just shy of 2MOA seems the norm. And being the entire platform uses the barrel as the "spine" or chassis makes barrel harmonics a nightmare and free floating impossible. It's amazing the rifle shoots as good as it does given the listed short comings.
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