[dan147]

Hey All, I've been having a lot of reliability problems with my Keltec RFB. When I first bought it, the first thing I did was get the gas system set up. I got it cycling reliably, then added a few extra clicks for good measure. No problems for awhile.

Then I got my suppressor. It could be due to other factors (I have not done extensive testing) but it seems that as soon as I threaded my new can on, I keep getting failure to eject issues.

I'll be firing, then suddenly the gun will jam up, with the bolt halfway forward. Applying pressure to the bolt does nothing, It won't budge. I take the magazine out, and a live round will fall out (but sometimes the extractor will hold it in place). It seems to me that empty brass that is still in the chamber is causing the bolt to fail to go all the way forward. The brass isn't properly getting into the chute.

I usually have to get a pair of pliers to manually move the brass (which is jammed up above the live round in the chamber) into the chute.

Here are my questions:

• Will overgassing an RFB (IE adding suppressor) cause these issues? Or is it due to other factors?
  
• What other steps can I take to reduce failures? Places on the gun I should clean and lube perhaps?
  
• Also, my brass always looked like this, even when the gun is functioning fine. Is this normal? Is the brass still reloadable? Is it relevant to my issues?

Thanks,

Dan

 

[TNC]

Have you seen this post down a few entries?

http://www.thektog.org/forum/f91/gas-ajust-suppressor-265905/

 

[dan147]

Have you seen this post down a few entries?

http://www.thektog.org/forum/f91/gas-ajust-suppressor-265905/

Interesting read. I did notice a fair bit of blowback, perhaps it was really overgassed. The question is, would that lead to reliability problems like I am having? Where can I get one of those suppressor pistons?

Also, can anyone chime in on the way my brass looks?

 

[ronmar]

Well initially you said you got it cycling reliably then "added a few clicks". What exactly does that mean? At any rate, what you described is not the proper procedure to setup the gas system. Depending on what "added a few clicks" means, you could have overgassed it to to point ocf causing those damaged case mouths, and to the brink of jamming. You shoot single rounds opening the gas adjuster each time untill it WON"T lock open on the empty mag, then you close the adjuster 1 or 2 clicks. If you look up in the FAQ section you will find links to videos I did on setting the gas and lubricating the RFB.

Did you re-adjust the gas after you added the can? You will have to do this, as well as when you change ammo type. You will probably find that you cannot get it to fail to lock open on an empty mag even if you remove the gas adjust knob/cap. If I recall correctly, removing the adjuster was KT's reccomendation for running supressed.

To answer your question YES, overgassing will cause the malfunctions you described. The Achillies Heel of the RFB is it's lack of overtravel and buffering. It just cannot handle too much gas. When overgassed the carrier is slamming into the thin rubber buffer pad up in the rear of the buttstock assembly. This is hammering the empty case held by the two extractors out of alignment, causing it to hang up on the ramp immediatly above the chamber mouth instead of traveling up it. This causes the brass case mouth damage you are seeing. When gassed properly you should not really see any case mouth damage...

 

[dan147]

Well initially you said you got it cycling reliably then "added a few clicks". What exactly does that mean?...

...Did you re-adjust the gas after you added the can?...

I took the gas cap off, put it back on, then tightened one at a time till the bolt locked back. Then tightened two more clicks. Is this wrong/backwards?

Thanks for all the excellent info. What if I can't get the bolt to NOT lock back when the gas cap is off? Where do I get suppressor piston?

 

[lateck]

Contact Kel-Tec and let them know what suppressor you are running.
They will sell you the proper piston.
Then you will need to reset the gas cap to a different point.
The RFB is a interesting rifle...
I love mine.

Lateck,

 

[Liberty4Ever]

Also, can anyone chime in on the way my brass looks?

You shouldn't have any trouble reloading the brass shown in your picture. The neck expander will fix that defect, but it'd be better if you annealed the case necks before resizing. If you had the bad luck to chamber a cartridge so the neck is dented in the same place a few times and don't anneal the case necks, you could get a case neck crack. That's not dangerous, but it would limit the number of reloadings you might get from your brass. In practice, I wouldn't worry about the case neck dents if the picture is representative of what you're getting. Mil-surp once fired brass is cheap enough. However, as ronmar commented, it'd be much better to get your RFB running properly and not have the damaged brass... and far worse consequences of overgassing.

 

[henshao]

Suppressors cause a huge amount of additional backpressure, and require a totally different gas setting (or setup as the case may be)

Like a car, if you add some sort of super-restrictive exhaust system, you'd have to change the cam to compensate

 

[flyer]

I experienced two interesting changes while shooting the RFB. Accuracy was very good from the start but the case mouths were getting that same dent. After 40 rounds, I was able to back the gas off 4 clicks (18 total FB) and still get perfect function - dents were a bit less. Around 100 rounds the case mouth dents ceased and I was able to back the gas off (4 more clicks) to 22 clicks FB and still get perfect reliability and no dents. I think the rifle breaks in all the parts and cycles easier. I have heard another guy that had to back his gas port off to 40FB with the suppressor. I've also heard of people having to get a new piston because they couldn't back it off enough. Call Kel-Tec, they seem to be very helpful with these issues. My .02...

 

[TNC]

I experienced two interesting changes while shooting the RFB. Accuracy was very good from the start but the case mouths were getting that same dent. After 40 rounds, I was able to back the gas off 4 clicks (18 total FB) and still get perfect function - dents were a bit less. Around 100 rounds the case mouth dents ceased and I was able to back the gas off (4 more clicks) to 22 clicks FB and still get perfect reliability and no dents. I think the rifle breaks in all the parts and cycles easier. I have heard another guy that had to back his gas port off to 40FB with the suppressor. I've also heard of people having to get a new piston because they couldn't back it off enough. Call Kel-Tec, they seem to be very helpful with these issues. My .02...

I agree. Nearly every AR15, AR10, and bullpup I've ever had seemed to have a small break-in period. You could feel the difference even in how they hand cycled after 50-100 rounds. I think most semiauto's experience the same thing.

 

[judcargile]

I have the longer piston and have the gas cap removed. I have zero problems. Nothing but 168 gr.

 

[dan147]

Hey all, quick update. First of all, thanks for all the excellent advice. You've all been great.

I went to the range today to readjust my gas system. As I expected, the bolt locked back with the gas adjustment knob removed.

After that, I went ahead and fired again with both the suppressor AND the gas adjustment knob removed. Nothing on the muzzle, just bare threads. The slide STILL locked back. I fired three rounds just to be sure. It locked back every time. And it wasn't a malfunction... hitting the bolt release after each of those three rounds resulted in the bolt slamming home just fine (and ejecting the brass each time, like normal)

Am I doing something wrong? I can't get the gun to fail to lock back. Insight on this would be much appreciated. Thanks

 

[TNC]

I'm guessing that you're over gassed in at least suppressor mode...and maybe even in normal firing. As ronmar often points out, the RFB doesn't fare well over time with harsh recoil as it has a minimal buffer.

 

[henshao]

You've done all you can, your gun is defective, send it to KT