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Discussion Starter #1
Good day -- I have 2nd gen RFB that has been fired ~45 times. While firing some 180 grain Winchesters, the bolt began to stick in the rearward position after firing. At first it was very, very stuck. But then, subsequent shots would also lock the bolt back, but it could be pushed forward with only a little resistsance.

It is NOT the "last-round-hold-open" mechanism.

Also, even when the gun is empty, manually cycling the bolt brings it through a "sticky" part.

I also have a question about the gas setting. What is the optimal way to set it, and if it is over-gassed, could that be a problem? Or will that only result in unnecessarily higher recoil?

Anyone else getting the tips of their bullets mangled?
 

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Good day -- I have 2nd gen RFB that has been fired ~45 times. While firing some 180 grain Winchesters, the bolt began to stick in the rearward position after firing. At first it was very, very stuck. But then, subsequent shots would also lock the bolt back, but it could be pushed forward with only a little resistsance.

It is NOT the "last-round-hold-open" mechanism.

Also, even when the gun is empty, manually cycling the bolt brings it through a "sticky" part.
There are two cross pins in the carrier that hold the bolt to the carrier. The rear pin of course is the captive pin that can be pushed aside with the tip of a bullet to remove the bolt from the carrier. The forward pin that the bolt hangs from is a roll pin and needs to be centered in the carrier. Since it is in the middle of the slide groove, IF it is a little out to one side or the other, it could be hanging up on the back edge of the receiver. It is a little harder to see on the 2nd gen carrier as it is recessed in a hole in the carrier channel. I had this problem on mine and used a drift to recenter the pin. It has not moved since, so I think it just wasn't quite seated deep enough/in the center when assembled.

I also have a question about the gas setting. What is the optimal way to set it, and if it is over-gassed, could that be a problem? Or will that only result in unnecessarily higher recoil?
Anyone else getting the tips of their bullets mangled?
The optimal way to set it is described in the manual, and yes, overgassing the system can cause problems. load a single round in a mag and fire it. If the bolt locks open, open/unscrew the vent cap. Repeat this process untill the bolt fails to lock, then close the adjuster 2 clicks. The RFB has very little room for overtravel and only a thin rubber pad for buffering once all the travel is used up. Too much gas causes the carrier to slam into the bufferpad. In addition to causing harsher felt recoil, this sudden deceleration interferes with the empty case ejection process, even going as far as knocking it loose from the extractors, and causing it to jam onto the upper ejection feedramp...

Another thing you mentioned is damaged tips? This could indicate a mag problem, and the tip of the bullit hanging up on the lower feedramp up into the chamber could also cause the open hangup you described as the bolt is hung on the case rim and the tip is jammed on the feedramp with the round still hung in the feedlips of the mag. A quick check to perform is when it jams open, engage the safety, and while stillpointed downrange, try and remove the mag. If it is a jammed live round, the mag will most likley pull it clear of the bolt and the bolt will close and you will have a loose round come out with the mag, or have a damaged tipped round in the top of the mag. if the bolt stays open, look up inside the magwell and make sure there isn't a live round holding it open... If not, then something else, such as the crosspin in the carrier is holding it open.
 

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Discussion Starter #3
Okie dokie... I found the pin, and when I view down the groove of the bolt, I can see that the pin is in the channel just a teeny-tiny bit. I shall try to use a tiny rod to drift it back.

I'm inclined to use a very small allen wrench of an appropriate size and a hammer to lightly tap it back to center.

Is there any other advice on this particular issue?

Also, regarding mangled tips of the 308 bullets... that does seem like a magazine issue, however, as soon as I realized that was happening to the bullets, I took a dremel with a tiny sanding drum to the "mouth" of the magazine to make it wider. I tried to gauge when I was done with the modification based on when it appeared that the cartridge would slide forward without making contact with the lip of the magazine. It seems like the tips aren't taking a beating anymore, but it does look like the side of the bullet -- not the cartridge, the actual bullet -- is still getting a little bit of a skinning. Basically it appears that some of the jacket is getting scrapped off.

So I guess my question is; it seems odd that the magazines need to be modified that much, and does anyone else need to do this? Has anyone else seen some damage to their unfired cartridges? I only notice this because I've dry-cycled some cartridges through my gun. I realize that this is generally frowned on because stacking un-fired cartridges in the chute could lead to disaster -- but I keep the rifle on a towel, muzzle down, and ensure that the cartridge completely clears the gun before moving on to the next. Is it possible that more people are having beat-up cartridges but not noticing them because they aren't dry-cycling?

Thanks for the advice.
 

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I bought 10 Steyr mags not long ago, and I had no issues. They were from various years, and in various condition. Something sounds fishy. That said, I've never dry-cycled the RFB, so perhaps it's happening and I just don't know about it. I'd think it would show up with poor accuracy on target, though, and with proper reloads I have no issue. When you say cartridges, it appears you mean the bullet, in which case I've never looked at them. My brass comes out in great shape, a little wear from the chute, but nothing odd.

I unpacked my ten magazines, put them through an ultra-sonic cleaner, dried them immediately, and went to town. No issues. Good luck figuring out your issue.
 

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When you are hand cycling them, ane you loosing the bolt from full open and allowing it to pick up the live round at full speed like it would when shooting? Or are you slowing it down with your hand on the charging handle? If you are holding the charging handle/following the bolt, that may be causing some additional scraping on the bullet/case from the magazine lips...
 

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Discussion Starter #6
I knocked the pin back to center, and hand-cycling the bolt seemed to run smoothly. I went to shoot yesterday, and after carefully setting the gas by the instructions, I went four shots in, and the bolt started sticking again.

I field-stripped the rifle, and it seems that little pin has drifted off to the side yet again, causing the bolt to hang up. I've only got ~30 rounds... maybe 40... but no more than that.

I can take pictures of the specific problem, if that helps. I'm concerned that I didn't drift it far enough to center. However, I'm also concerned that it seems to want to migrate out. Suggestions? Also, the location ... it makes it very challenging to work with. The hole to access that pin is so small, I'm not sure what to do specifically. Last time I re-centered the pin, I used a flat allen wrench as the tap, then I set the bolt on its side on the floor and tapped the top of the allen wrench with a hammer. I can certainly do this again, but I'm concerned that I'm damaging the pin. That I'm flattening and widening out the head of it so that it won't go back in appropriately.

Thanks in advance.
 

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Discussion Starter #9
Contact Kel-Tec. They offered to look at the gun if I sent it in. I did, they sent it back after solving one-and-a-half issues. Gun runs like a champ now.

The primary issue was that the bolt-spring-pin had worked itself loose and was getting into the channel. This caused the bolt to fail to slide smoothly.

The secondary issue - which I don't believe affected anything - was that the "Cam Pin Retainer Spring" was loose, and it did not retain the cam pin. Even though it didn't contact the cam pin, the cam pin had nowhere to go and was thus merely a problem in theory, not in practice.

All fixed now. Thanks for all the help.
 

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Contact Kel-Tec. They offered to look at the gun if I sent it in. I did, they sent it back after solving one-and-a-half issues. Gun runs like a champ now.

The primary issue was that the bolt-spring-pin had worked itself loose and was getting into the channel. This caused the bolt to fail to slide smoothly.

The secondary issue - which I don't believe affected anything - was that the "Cam Pin Retainer Spring" was loose, and it did not retain the cam pin. Even though it didn't contact the cam pin, the cam pin had nowhere to go and was thus merely a problem in theory, not in practice.

All fixed now. Thanks for all the help.

I think if the cam pin was causing issues, it would have been stopping the bolt at a much farther closed position. I had the same forward pin issue about 200-300 rounds into my RFB adventure. Tapped mine back into center and it hasn't moved since. I guess yours was a little looser. Glad you got it worked out...
 

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Discussion Starter #12
TROOPER: do your bullets still get marked when you dry cycle?
Yes! A lot! I had one piece of steel-cased, el-cheapo Monarch 145 gr 308 that got its jacket scrapped completely off on one portion of the bullet. Many others get tip-mangling as well.

***bear in mind that when I "dry-cycle" the gun, I have it perpendicular to the ground, muzzle down, on a towel, and I ensure that each live round ejects before cycling the next... don't want a round going off in the ejection chute ***

I have two different FAL mags - one which came with the gun marked, "DSA Arms" (I think), and a different one which is made by someone else -- can't remember who. Both were purchased 'used'.

To rectify the cartridge damaging, I took a dremel with sanding drum to the front lips of the FAL magazine. I made the mouth much, much wider, so that the bullet (still in the cartridge) makes minimal-or-no contact with the magazine as it is peeled off of the stack.

I have had some soft-points still get their tips beat up some, but not nearly to the degree that it was earlier. I may yet get the dremel out again.

As noted somewhere on the KT website, or maybe the RFB user's manual, "there are a variety of FAL magazine manufacturers, and relatively wide variances between them." (paraphrase). Taking that into consideration, I've made those minor modifications with good results.

The minor differences between the FAL magazines on the market right now might explain why I had this issue while other's haven't. I do suspect that more people have this issue and don't know about it because they don't dry-cycle their gun.

I have also noticed that my "bolt-release" works just fine, although I have read or heard that some people's bolt-release isn't quite as functional, because when the bolt is held open, the springs may not have enough tension to reliably peel off a new round, and return to battery. Someone mentioned to me that this was the reason that the two shooters in that promo YouTube video both pulled back on the charging handle after reloading in that video.

That said, I notice also that my RFB is a second generation, or third, or whatever, and its possible that this issue was addressed. Its also possible this issue was mostly internet rumor, too; I have no way of knowing.

Again, thanks for all the help.
 

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Mine dosn't make any significant marks on the rounds when cycled. I have only the one metal mag provided with teh rifle, and a bunch of thermold mags. I get a small line in the middle of the case, that I believe is caused by the bolt riding back over the round in the mag. I have seen round nosed bullits get damaged as the round comes far enough forward to hit on the little lip up onto the feed ramp. On a sharp pointed round, the point hits above the lip and pops the round up and out of the mag. I would say scratches on the bullit jacket are either from a burr on the forward magazine feed lips, or perhaps from a rough spot on the top of the feed ramp right where it enters the chamber.

Have you tried marking the top of the rounds with a sharpie as you load them into the mag? This will tell you the orientation of the round when the damage occurs and possibly point you toward the issue.

Mine also chambers from the bolt stop just fine, as has every firearm I have ever used. The use of charging handle vis bolt stop is probably a training thing, as I know many combat handgun courses emphasize racking the slide to the rear vis using the release to chamber a round after a mag change. Especially in handguns, grip is important, so probably better to not alter your grip to activate a release. Also in handguns, the short fat round has to make quite a series of radical movements to get cleanly from mag to chamber. There may be some timing involved, so it may be more reliable to fully cycle and release the slide to chamber more like the action does when firing. A rifle chambering is a little more linear, but if dirty, it could work better with a little extra force, so train like you should fight also makes sense...
 

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The use of charging handle vis bolt stop is probably a training thing, as I know many combat handgun courses emphasize racking the slide to the rear vis using the release to chamber a round after a mag change.
On some it is due to functional reasons. On FNP-45s you are supposed to work the slide because the ambidextrous slide stop/release (they call it both in the manual) won't always come down on both sides. I've experienced this on multiple occasions with my FNP-45 Tactical. FNH says it is working as intended.
 
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