Hoping for no let down. (aka: what the...with pictures)

Discussion in 'RFB High Efficiency Rifle' started by hib, Oct 27, 2017.

  1. hib

    hib Member

    Oct 27, 2017
    First let me note I own 2 P3ATs and a KSG and have absolutely zero issues with them via 1000s of rounds. I wish I could say the same for my RFB.

    Up front questions:
    -Are newer bolts black? (nitride or the like vs the other coatings)
    -Should the bolt have a flat section where the 332 cam pin rides?
    -Should there be a stiff part of charging prior to hammer cock at approximately 1 inch pull?
    -After cocking should there be a stiff region approximately 2 inches into charge handle pull?
    -Should magazines require a slap so hard it is actually uncomfortable to the point after 10 mags you have the beginnings of bruises on your hand? (This one is interesting because the Metal FAL mags dont do this but the Keltecs do. The metal fal mags just have too much friction for the gun to cycle properly).

    Main issues:
    -Double feeds.
    -Failures to "extract".
    -Failure to "fully cycle".

    Been waiting years to get an RFB both due its new nature and hopefully allowing the "kinks" to be worked out but even simply finding one. Finally got one but unfortunately I went from excitement to WTF to "I gotta be doing something wrong" to disappointment and now "sure seems like somethings irreparably busted, its junk".

    This was purchased new and based off what I can tell it should be at least Gen 2 but the gas piston... I have no clue. Its as if these are made by a half dozen different outlets and they have a lottery as to what rifle gets what based off pictures I have seen and people spoken to in passing.

    I have approximately 280 rounds of PMC and Aguila through the system(200 PMC, 80 Aguila). I also have 6 keltec polymer mags and 3 metric metal FAL mags.

    -One of the keltec required being dismantled and areas sanded down as the front of the lift would not go all the way to the top consistently resulting in failures to feed. No other keltec mags had this issue.
    -The FAL metric metal mags while they fit better than the Keltec they are a what I would consider a complete and total failure to the extent they might even be dangerous. They seem to have far too much friction (tight fit for round) for the RFB to extract them.

    -Neither worked better or worse than the other and neither has any issues whatsoever in other firearms so I seriously doubt its an ammunition issue.

    At this point which includes numerous cleanings using numerous methods to the point of a full field strip including gas piston etc and readjusting the gas repeatedly shot by shot single round per mag etc with consistent ammo I can say without question from a firearm perspective this thing is 100% unreliable. That is not to say it fails every time but rather so often and seemingly randomly you would almost be better off with zero success vs the 20-40% failure rates in every possible way from feeding and extraction to cycling. About the only issue I have not seen is weak strikes etc. I have not had a single 20 round magazine fully cycle and most have had 3-5 failures each run with some having 1 failure. There seems to be no reason as to how many rounds are in mag before failure. Usually the failures are a lack full cycling and not failure to feed. This would indicate a gas issue but the most consistent I have seen is around 12 clicks open and no amount of burning ammo and even click at a time adjustment has made resolved this. Also most failures result in mangled casings as seen in the picture associated with the keltec mag.

    Regarding gas adjustment if I have it open too far it never cycles. Too closed and the failures are a crap shoot. Again 12 seemed to be the "sweet spot" for all of this ammo but it was still, for all intent and purpose, unreliable. The system came at 17 out of the box.

    I have yet to contact Keltec nor the shop as I like to try and definitively determine its not user error on anything I work with before going back to them. Call it the engineer in me.

    I have Flitz'd areas of wear to snot slick. The action is smooth other than two sections (see pictures). This made some difference but it was marginal and so small it may simply be perception.

    Total and complete loss at this point aside from contacting Keltec etc. I'd much rather prefer this just work like my other Keltec firearms and be a content owner.

    Charge pull length were from a dump I had originally and contained typos etc. The first stiff point is around 1" and the second 2".

    Attached Files:

    Last edited: Oct 28, 2017
  2. M4V3R1CK

    M4V3R1CK Active Member

    Oct 21, 2008
    A few points of interest, before I start talking about your problem:
    You have a late second gen, with the gen 2.5 piston and bolt. There is only one factory, but they make improvements as they go along, to make it easier/cheaper to produce or to improve reliability (not that you'll believe that one). The "Kel-Tec" mags are actually Thermolds. I have 10 surplus metric, and 6 DSA SA58 MAGS. No issues with any of them. Magazines should not require excessive force to seat them. ESPECIALLY if you're loading on an open bolt. Mine doesn't like loading a full mag on a closed bolt, so I only change mags after it locks open. Also: all of my brass looks almost like your "yes, but..." picture. It's not a problem, if it's not impacting too hard. Brass is soft, and can get pretty dinged up, pretty easily.

    Here's some charging handle tension data for you:
    I collected this from my 2nd gen, while working on a special project. Hopefully will be returning to said project soon.

    Your charging handle behavior is confusing. You say 1" and 6", but it looks more like 1" and 3" or so in your pictures My bolt carrier won't even MOVE a full 6", so... I dunno what you're talking about.

    If you're having failure to extract or failure to cycle issues, here's a quick test, since you're having so much trouble with it:
    Lock the bolt back. Insert an empty magazine (shouldn't take much force to get it to latch). Press down on the bolt release. Does the bolt fully close? Repeat test with a live round in the magazine. Does bolt fully close? Repeat these tests on ALL of your magazines, and report back with results.

    If your weapon isn't fully cycling, it's because of a lack of gas. Double feed... might be a broken extractor issue (one of mine was cracked for years, and I didn't know it, because previous owner had overgassed the hell out of it, but it still worked... just was a little sluggish)
    hib likes this.

  3. hib

    hib Member

    Oct 27, 2017
    Thanks for the information on the generation.

    I have updated the pull lengths and noted that in the post. These were originally from a dump I had prior of "after thought notes" and I suspect I simply replaced numbers. The pulls are 1" first friction, 2" second friction. Approximates.

    In your graph I am not seeing a units. Can you indicate what these are and suggested tools for testing?

    Bolt closing on empty and loaded magazine seem to work manually even with the the metal FAL metric mags.

    Perhaps of relevance is if I load up any magazine but the 2 on far right in magazine picture manually cycling works effectively flawlessly. Again this seems to me to indicate a gas issue. ie: If I man handle the cycle anything runs.

    I have been unable to identify any extractor issues upon inspection but perhaps I am simply not looking close enough or doing what it takes to detect a fracture etc.
  4. ronmar

    ronmar Well-Known Member

    Oct 2, 2010
    What Maveric said about bolt travel... My RFB has about 4 5/8” of travel. With the hammer down first drag is when the bolt unlocks and starts to press against the hammer at approx 1/2”. With a cocked hammer this occurs at about 1 3/4” as the bolt starts to ride over the cocked hammer face. Once over and riding on the face of the hammer the drag is pretty uniform the rest of the way back. Maverics load data looks like mine feels with the hammer down:0 what does the inside of your buttstock look like. We helped with an issue here where it looked like an extra long screw was used in the top screw location in the buttpad. This screw protruded far enough forward that the bolt actually hammered it into junk and it was interferring with the action. As for other drag inducing issues, check the pins that hold bolt to carrier, particularly the forward rollpin. Make sure it is centered as it can interfere with the carriers travel in the receiver slide grooves.

    Only mag seating issue I have heard of is with a full mag on a closed bolt. You are rocking them in right? Top front in first, rotate the bottom to the rear and up. The thermolds can be a little tighter fit in the magwell till mags and well wear-in. The bottom of the receiver is matched to the contour of the top of the mag. Any mis-shape will impede seating. Any issue with the locking tooth will also interfere with the final lockup.

    Ok, that first brass pic tells me one of two things. it is really overgassed or your extractors are not functioning properly or both. In this design it is absolutely vital that the extractors function correctly. If they don’t, the symptoms could be leading you to mis-adjust the gas which only makes things worse. Since extraction and feed occur in the same area an extractor issue could contribute to feed issues.

    First to the extractors: With the bolt removed Take an empty case and snap it into the extractors. The extractors need inward pressure to grip a case so they rub on the side of the bolt and do not move freely untill a case is inserted. With the case in, It should immediately snap the brass to the up position. The whole rifle function hinges on the ability of the case to snap up under pressure from that spring in the bolt. If that works try a loaded round, it should be able to do the same thing with the added weight like in this video If it does not, that is the first problem that must be overcome. Oh, and use actual brass, not a snap cap as they are not always produced to spec and may not allow the extractors to come free of the side of the bolt.

    overgassing: A little dent on the rim is a symptom of overgassing, but what happens when it is really overgassed is the carrier hits the buffer pad back by the buttpad so hard that it jarrs the case out of the extractors and the case mouth gets mangled as it then unpredictably hits the porch over the chamber mouth where the extraction ramp starts. Sometimes it even forms the mouth around that feedramp and really jams things up. The only criteria for adjusting the gas should be wether the bolt locks open on an empty magazine or not... If the extractors are working and the gas is set, your jams are being caused by something else...
    hib and M4V3R1CK like this.
  5. BlakeHanson

    BlakeHanson Well-Known Member

    May 31, 2015
    Most people download their full mags by one round, especially if they are putting them in with a closed bolt.
    Some mags won't even go in with a closed bolt if they are max'd-out.
    hib likes this.
  6. M4V3R1CK

    M4V3R1CK Active Member

    Oct 21, 2008
    +1 to Ronmar's analysis. (only exception is that my cracked extractor still passed the test, but was leaving slightly dinged brass) And yes, my numbers are all starting with the hammer down (fired).

    hib: my bad! You're right about the units! They are pounds force and inches travel.

    Here's my test setup of a ratchet strap and a luggage scale (I used 1/10" graph paper on the gun (not shown), and a wire pointer attached to the charging handle, to get my distances):

    My extractor crack was only on one extractor, and it was cracked underneath the U-spring, so I didn't see it until I detail-stripped the bolt, and the extractor came out in pieces. It still worked great, even broken.
    hib likes this.
  7. hib

    hib Member

    Oct 27, 2017
    Amazing feedback everyone and thank you! I will rig something up to do similar measurements and be more precise on where in the pull the friction exists.

    The extractors work as expected with both casing and a live round. I have only taken the bolt down to what is seen in the picture and removal of the firing pin.

    That video is what I used the second time I went out and adjusted the gas. What is concerning to me though is if I open it more than 12 it will repeatedly fail to lock open yet based off the brass casing dent it sounds like it is over gassed.

    Buttstock inside:
    Seems to look ok to me. I looked all over for odd hammering or gouge marks, seemingly out of place, long or loose screws etc.

    I have noticed with the bolt closed loading the Keltec mags are significantly more difficult. This is probably at least part of that issue. Due to the number of malfunctions I cant say with certainty when and if I was loading with or without a closed bolt. My suspicion is both which lead to further frustrations of seemingly inconsistent behavior.

    Testing both the method of loading a mag as well as one less round and open and closed bolt I can confirm open bolt or one less round makes a major difference in difficultly. Also angling the magazine when seating I found this easier when I first took it out but was thrown off by the fact the manual is very explicit on page 14 saying ""A loaded magazine is inserted straight up, not titled, into the rifle's magazine well until a "click" is heard." It then mentions using a "firm smack" to seat it.

    Clearly based off what you have told me and testing this with each magazine fully loaded, partially loaded and empty tilting the magazine is the correct method. At least for this RFB. I will be making a conscious effort to only load magazines this way now.

    If I can not get the bolt to lock open on an empty magazine at anything less than 12 and 12 is still leaving the dents and the extractors are working as expected. Could this still just be some kind of break in issue?

    Attached Files:

  8. M4V3R1CK

    M4V3R1CK Active Member

    Oct 21, 2008
    minor point: The RFB manual states "straight up" because the loading of the magazine is MUCH closer to that of an AR (straight up) than the FAL (hook and rotate), but it behaves best when you insert it with a little tilt, catching the front catch first, then snapping it into the rear catch, as you've noticed.

    Here's thought: After testing your pull force with an empty chamber (hammer down), take a fired case (undented), and load it into the chamber. Close the bolt on it, then load an empty magazine into the mag well. Drop the hammer, just to be consistent. Slowly pull back on the charging handle and see if there is a significant difference in the pull force near the end of travel. If it's not discernible, on paper, try again by hand, and see if it locks back on said empty mag, without requiring a lot of extra force.

    Repeat last test, but YANK on the bolt handle, to see if you can make a dent in the brass, by hand.

    Edited to add: Looking again at your mag picture... what was happening when the live round got the massive dent in it's shoulder?
  9. grindcore

    grindcore Member

    Nov 13, 2017
    I recently bought an rfb and have similar problems. My bolt is gold colored for what it matters. I'm no gun expert but these are my findings.

    Crushed cases, like where the front of the case gets smashed into a square, happened when undergassed. I had a harder time than that YouTube video made it seem to adjust the gas so I went in steps of 3. On some 146gr 762 I got the gas to adjust at +6. It would crush the casing at about +12-16. Strangely, it would not damage the case from +16 to 40.

    Double feed/no feed/round gets stuck in mag pointing out at an an angle seems to have been a magazine 'break in' and lube issue. I had to almost soak the bolt in oil and cycle a magazine(thermold) over and over until I could run all 20 rounds through the magazine without issue. I also started loading 18rds in them first to get any sort of reliable function. I think I shot each mag four or five times with 18 rds loaded and then started cycling live rounds through them at home, after about 4 times cycling them I could feel everything working much better. I also can put 20rds in.

    Also worth repeating, as the manual also states it, is pull the bolt lever back and let go. Applying any pressure pushing it forward causes a jam every time. Even just guiding it forward.

    I also feel resistance in the first inch or so of pulling the bolt lever but as its been pointed out at that point the extractors and the bolt are moving so it has more drag. Same thing with the lever near the rear of its travel.

    I'm working on breaking in some metal mags now but the dsa ones scrape the bullets, I had to deburr them a bit but the process seems to be repeating itself the same as the thermolds. I haven't shot with them yet so I'll see how it goes. Hopefully the bullets don't get too damaged just cycling them through the gun.

    I'll follow this post because it's so similar to my issues and hopefully we can iron the issues out. I'm with you in not wanting to trust this gun just yet, Im hoping it can be sorted out. I've already seen a big improvement in function already, but I want to see 200-300rds without a jam before I'd rely on the thing.
  10. hib

    hib Member

    Oct 27, 2017
    Attempted to collect pull data on my RFB using a cargo strap and free hand. The biggest difference I think Im seeing is second pull with no magazine. Perhaps the most important item to note are the purple dots and range. If I release the charging handle in that range regardless of the configuration the handle will hang and not return to the forward position. If I tap it or shake the firearm it will then return. That section hangs quite a bit and Im wondering if others see this happen.

    After further "polishing" and cleaning I ran 20 PPU 145Gr NATO brass through it with the same horrible results.

    I have picked up some TulAmmo 150Gr FMJ 308 WIN coated steel rounds as I have read the RFB likes steel. Great if so its cheaper but I suspect the results will be he same or worse. May find out this weekend.

    Attached Files:

  11. hib

    hib Member

    Oct 27, 2017
    Might be worth noting that the 3/8", 1/2" and 5/8" marks are very distinct and without question there are "positions" there consistently depending on mag presences and first or second pull. With a loaded mag the transition between 3/8 and 5/8 has a almost snapping or crunch feel. 3/8" and 5/8" seem to be the dominate points. This somewhat makes sense given what the bolt is going at that time but what I find a bit strange is the variation and I have little doubt those points are not very accurate as I have repeatedly tested pulls just to that point with no observed change and they are quite literally "stopping" points. Id have thought the bolt would largely act the same at this position and only really change between having a round ornot.

    Clearly what I would need to do for truly accurate measurements is put this on a bench with a recorder attached etc. The methods I had to use are simply unstable. I do think though it gives a good idea of a general what and where under what conditions.