[MadDogDan]

I just picked up my new 18" FDE RFD. Broke it down and cleaned and lubed it up. I am going to take it to the range tomorrow to run some rounds through it and to sight in both optics. I am a little confused about the gas setting. My manual says to bottom out the gas adjusting knob by turning it clockwise until it stops. Done. Now it says to open it up Bottom +40 clicks. The only problem is my adjuster only opens up Bottom +18 and it was set from the factory at Bottom + 14. I don't want to force anything so I thought I would ask here first. I read somewhere that people were setting it at Bottom +5 and going from there.

Guess I will see what I can find on Youtube.

 

[haugrdr]

Congrats on your new rifle!

You may have gotten an old manual...check it against this one posted on the KT website.

Gas adjust starts on page 25.

https://www.keltecweapons.com/media/catalog/category/rifles/rfb18/rbf18_series_manual.pdf

 

[MadDogDan]

Thanks, I looked at your link and my manual must be old because it does not say to start at 10 clicks. I noticed my gas knob is different as well. The new manual shows a slot so you can use a case head for adjustments. Mine has holes in the sides so you can use a bullet tip.

 

[ronmar]

If you go to the FAQ "sticky" subject at the top of the RFB forum(3rd one down from top) item number 21 has a link to a video I did on how to adjust the gas system. here is a link to it on Youtube

http://youtube.com/watch?v=5eD_C8J8Fkc

Your adjuster should go more than 18 clicks open, in fact you should be able to easilly unscrew it completely. Carefull not to loose the detent pin and spring. There have been some that have had issues with the detent pin being sticky. Look closely around the skirt of the adjuster cap and you should be able to see this pin. A drop of lube here might make it work easier...

 

[MadDogDan]

If you go to the FAQ "sticky" subject at the top of the RFB forum(3rd one down from top) item number 21 has a link to a video I did on how to adjust the gas system. here is a link to it on Youtube

http://youtube.com/watch?v=5eD_C8J8Fkc

Your adjuster should go more than 18 clicks open, in fact you should be able to easilly unscrew it completely. Carefull not to loose the detent pin and spring. There have been some that have had issues with the detent pin being sticky. Look closely around the skirt of the adjuster cap and you should be able to see this pin. A drop of lube here might make it work easier...

Some lube took care of the problem. I can now totally remove the adjuster. I will use Bottom +10 as a starting point.

 

[MadDogDan]

Congrats on your new rifle!

You may have gotten an old manual...check it against this one posted on the KT website.

Gas adjust starts on page 25.

https://www.keltecweapons.com/media/catalog/category/rifles/rfb18/rbf18_series_manual.pdf

Well the manual that came with my RFB seems to be correct as to the gas setting. It came from the factory set at B +14 so I tried my first round there. It locked back so I started opening up the gas knob 5 clicks at a time. I got to B +40 like the manual said to start and the bolt still locked back. I opened it up more but stopped at B +49 because the knob was wobbly and seemed like it was about to pop off and I did not want to loose the detent pin and spring. The bolt still locked back on an empty mag (shooting just one round at a time like the manual said). I decided to close the knob up a little to B +40 so it would stop wobbling.

I was shooting 145 grain FMJ boat tails (brand unknown, plain white imported boxes but brass cased, not steel cased). Whatever this ammo was it was pretty clean, not smelly and had less recoil them my AK's but just a little more (and I do mean just a "little") then any of my AR's. I only went through 80 rounds today (ran out of time) but I could shoot this thing all day and not feel it in my shoulder. It was veery comfortable.

 

[ronmar]

Yea, that has happened a lot here with the second gen rifles, cannot open the adjuster far enough to get it to fail to lock open/comply with the adjust procedure in the manual...

When you broke it down and cleaned it, did you put any lube in the gas piston? That is the one place on the gun that you DON"T put any lubricant. Lube there causes the piston to seal better and will give you the symptom of being overgassed like you described. it will also gum-up as the oil catches and holds the particulates in the gas...

SO if the gas piston and it's bore are clean and dry, unfortunately as you shoot it more, the action will most likley loosen up/wear-in requiring less gas to function making this problem worse.

What is the downside? Well this rifle has VERY LITTLE overtravel room in the action. My 1st gen has a little under 1/2" beyond the point where the Bolt Carrier Group is held open by the bolt stop. At the end of this distance is a thin little rubber pad that the carrier slams into. If it is overgassed to the point that the BCG is slamming into that pad, it can eventually hammer the gun to the point where it starts to come apart...

Some here have "adjusted" the gas piston so that the lock-open point is within the gas adjustment range. Others have sent their rifle back to KT to get it to operate as specified in the manual...

Good luck

 

[MadDogDan]

Ronmar,

I didn't put any lube in the piston. In fact that was the only thing I didn't take apart. I did put a little lube on the detent pin and external notches so that it would turn easier but none "inside" the piston. If I completely unscrew the adjuster knob can I take it off and get to the piston to make sure it is dry?

 

[ronmar]

You get to the piston by field stripping the rifle. Pull out the carrier assembly. The right hand spring guide rod extends out the front a little and has a small length of spring on it that pushes against the back side of the piston. Once the carrier is out of the way, simply pull the piston out toward the rear...

 

[MadDogDan]

You get to the piston by field stripping the rifle. Pull out the carrier assembly. The right hand spring guide rod extends out the front a little and has a small length of spring on it that pushes against the back side of the piston. Once the carrier is out of the way, simply pull the piston out toward the rear...

Just got done pulling the piston. It was bone dry. The RFB is one of the easiest weapons to strip down. I was amazed how fast it comes apart. Just had to take the time to read the manual. I made sure when putting the piston back that the gas ring gaps were staggered like you would do on an AR piston.

I think I will use the RFB in my next 3-gun match as I already use a KSG in local matches.

 

[BlakeHanson]

..Just had to take the time to read the manual. I made sure when putting the piston back that the gas ring gaps were staggered like you would do on an AR piston..

Ok, now I'm confused.
His RFB is gen 2, the piston has no rings like a gen 1, which has piston rings like an AR.

I should probably drink more and read less.

 

[ronmar]

Yea, I thought it was a gen2 also... Maddog, Did you have to rotate the gas piston to remove it(has keyed teeth that hold it in place)?

IF it is a first gen with AR rings in the piston, aligning the gaps might actually help with your overgassed symptoms by making the piston seal less effective...

 

[BlakeHanson]

Yea, I thought it was a gen2 also... Maddog, Did you have to rotate the gas piston to remove it(has keyed teeth that hold it in place)?

IF it is a first gen with AR rings in the piston, aligning the gaps might actually help with your overgassed symptoms by making the piston seal less effective...

It's a gen 2 per his pic he posted in the other thread:headstratch:.

I picked it up today.

FDE was not available yet on gen 1's.

 

[MadDogDan]

Yea, I thought it was a gen2 also... Maddog, Did you have to rotate the gas piston to remove it(has keyed teeth that hold it in place)?

IF it is a first gen with AR rings in the piston, aligning the gaps might actually help with your overgassed symptoms by making the piston seal less effective...

Not sure what Generation it is but the serial number is T2V71. I did not have to rotate the piston to get it out. Just pulled it straight out towards the butt of the gun. I took two pictures so maybe you guys can tell me what I have. before I put the piston back I aligned the gaps in the three gas rings to help in bleeding off some excess gas. If you look at the tip (front of piston) it has three flats and one radiused portion.

Hope this helps.

I looked through all the posts in the "show me your piston" thread. Every picture of pistons that look like mine have "no" gas rings. Are they not needed? Is KT putting rings on all of the newest rifles to come off the assembly line? I just noticed the serial number chart. If I read it correctly mine is 9,771. What generation does that make it?

 

[ronmar]

OK, havn't seen one like that before... Second gen piston with snaprings like in a first gen...

If lining up the rings dosn't help, you could try removing them one at a time to allow more gas to get past them. Or even sand the outer edge of the rings to make the seal less effective.

The lack of rings was one of the things I didn't like about the second generation system when it first came out. The rings allowed for easy and reversible user tuning. Take too much off, just replace the ring. It might even make the piston tuneable enough to work comfortably with a supressor fitted...

 

[BlakeHanson]

OK, havn't seen one like that before... Second gen piston with snaprings like in a first gen... The rings allowed for easy and reversible user tuning. Take too much off, just replace the ring. It might even make the piston tuneable enough to work comfortably with a supressor fitted...

So I guess now everyone will want a generation 2.0.1 piston now.
My gen 2 piston seems so "yesterday".

 

[MadDogDan]

Anyone know how many piston designs are out there now. Mine may not be the latest/greatest. My serial number is in the 9,000 range. Anyone know how many RFB's are out in use now?