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Discussion Starter · #1 ·
Got a new KSG about a year ago. After shooting 50-60 rounds the forend became progressive more difficult to cycle. After disassembly I found my bolt carrier had bent where the long thin arms are welded to the rectangular “plate” that engages the bolt. When this happens the bolt carrier doesn’t line up properly with the plastic butt stock rails that usually support the bolt carrier. It finally became so bent it stopped cycling. I could not reassemble the bolt stock and had to return it to KT in 2 pieces with the butt stock off. Excellent customer service from KT keeping me updated re: receipt of KSG, update when service started, finished, and on its way back to me. The ~ week of shipping was longer than in+out of thir shop. Got it back with a nice list of repairs and replacement parts. Cycled it empty and was pleased with how smooth it was. Went to the range and shot 40 rounds and same thing has started to happen again. I’m using 2 3/4” slugs and 00. Same problem where cycling is progressively difficult and again I found the bolt carrier is bending such that it binds on the rails of the butt stock.

Has anyone heard of this before or know why it might be happening? I called KT and I was supposed to hear back from a gunsmith but nothing yet. I do think their service is excellent and I love to shoot this gun! Just looking for suggestions or answers. Thanks in advance.
 

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Got a new KSG about a year ago. After shooting 50-60 rounds the forend became progressive more difficult to cycle. After disassembly I found my bolt carrier had bent where the long thin arms are welded to the rectangular “plate” that engages the bolt. When this happens the bolt carrier doesn’t line up properly with the plastic butt stock rails that usually support the bolt carrier. It finally became so bent it stopped cycling. I could not reassemble the bolt stock and had to return it to KT in 2 pieces with the butt stock off. Excellent customer service from KT keeping me updated re: receipt of KSG, update when service started, finished, and on its way back to me. The ~ week of shipping was longer than in+out of thir shop. Got it back with a nice list of repairs and replacement parts. Cycled it empty and was pleased with how smooth it was. Went to the range and shot 40 rounds and same thing has started to happen again. I’m using 2 3/4” slugs and 00. Same problem where cycling is progressively difficult and again I found the bolt carrier is bending such that it binds on the rails of the butt stock.

Has anyone heard of this before or know why it might be happening? I called KT and I was supposed to hear back from a gunsmith but nothing yet. I do think their service is excellent and I love to shoot this gun! Just looking for suggestions or answers. Thanks in advance.
Did you ever get a solution as to what was happening, and why it was happening again, with that bolt-carrier? Did the KelTec Gunsmith ever get back to you?
 

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Discussion Starter · #3 ·
Did you ever get a solution as to what was happening, and why it was happening again, with that bolt-carrier? Did the KelTec Gunsmith ever get back to you?
Absolutely. Kel Tec service has been truly outstanding. Lynne Briggs is delightful and prompt. It took a while as their engineer was on vacation but they had him look at it and they took care of the problem. Received my KSG back working perfectly. Only additional info was recommendtions to use SAAMI spec ammo. May have been some issues with CIP (euro standards) and head spacing.
 

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I have had the same experience. That bending can lead to the action locking up. I am waiting for KT to get the bolt carrier back in stock so I can get mine up and running again. There are other forums that have discussed the Ammo issue. One theory is that the parkerized chamber makes extraction of some shells very difficult and that leads to the bending. Once mine is operational with a new carrier I’m going to limit the Ammo selection to US brands.
 

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Discussion Starter · #5 ·
It’s frustrating. I have been only using US ammo shooting Federal slugs since my last repair. I shout tentatively - being cautious and worried that the same thing starts again. I was thinking about switching to only US low recoil as well, hoping to prevent another recurrence.
It’s interesting to look at the KS7 bolt assembly - there appear to have been some changes (I expected to see the exact same bolt design - just one less mag tub and no selector). But I suspect there have been enough issues that a redesign was necessary. And unfortunately from looking at it I don’t think you can swap out the KSG parts for KS7 parts re: bolt, bolt carrier, or carrier arm. Keep the forum up to date with your experience, and thanks for posting.
 

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Here's an excerpt from a discussion about the bending bolt carrier from a GlockTalk forum:
"Of particular disdain was the weakness of the bolt carrier/bolt arrangement. In a "normal" pump shotgun the bolt is fully supported between action rails and the inside of the receiver during all cycling actions, but due to the bullpup design of the KSG the long and skinny rails of the bolt carrier are NOT fully supported when the action is closed, and as such if a round were to get stuck in the chamber (more on that in a moment) and one were to apply significant rearward pressure to the action in an effort to open it, the carrier rails can and will bend inwards because there's no bolt there supporting them, and when this happens the twisting of the carrier rails causes the bolt to fall out of its recess at the rear of the carrier and locks the shotgun up as tight as a clam's arse, which requires disassembly to correct. WTF, over.

About the chambers...it seems that a disproportionate number of people have purchased brand new KSG shotguns only to find out that the chambers appeared to have been bored out with a rock, and "somehow" got past Kel-Tec's QC efforts. So terrible were they that some couldn't even chamber a round, and if they did manage to force one in, extraction was damn near impossible. Enter the phrase "fluff and buff", whereas these unfortunate KSG owners had to either send their KSG's back to Kel-Tec or they had to use suitable abrasive methods to render their chambers usable, e.g., using hones typical of those used to clean up the cylinder walls of internal combustion engines, along with performing work on it's other components similar to what the Glock community refers to as the ".25¢ trigger job", because the intermingling trigger components were so rough or had such sharp edges that these conditions impeded smooth function.
" A lot of people suggest polishing the chamber so as to eliminate the resistance to shell removal during the racking process. If you watch the MCarbo instruction video on replacing the trigger you will note how amazingly smooth the action is on their KSG, its like the action on a KS7. I suspect those guys have really "fluffed and buffed" their KSG.
 

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Discussion Starter · #7 ·
OK - a little science and research today about KSG failing to extract and possibly bending the bolt carrier. No shade - the KSG is broken down, trigger group is totally off, no bolt or bolt carrier - just the chamber and barrel. But these are live, unfired rounds

Taking several different brands and caliber of shells, some high brass and low brass, and even some Aguila mini-shells. Federal buck and slugs, Rio buck, NSI buck, Sterling #5 shot, and my dummy rounds. All slide in to and out of the chamber very easily - no force. I’m sure the plastic shell (and maybe also the brass) expands and is fatter (and clearly longer) after being fired. But still easy in is likely to be easy out.

However not the last shell - a Sterling slug. This would not slide into the chamber without some coaxing, and required a little prying to get it out. Sterling is made by Turaç in Turkey, to CIP specs. Not sure if the specs in this batch were off, or ooor quality control, or CIP is allowed to vary or different compared to SAAMI specs.

So failing to extract might occur if the shell is tight (especially right after firing when hot and most expanded) which can lead to a double load.

Finally, when cycling the KSG, the forend is pushing the bolt carrier back. If there is excess resistance with a shell tight/stuck in the chamber you end up using the two skinny carrier arms to push the bolt against additional resistance to extract a tight shell. This could lead to failure (bending, cracking) of the bolt carrier arm the point of connection to the carrier plate. The mechanics seem similar to comparing Western vs. Japanese wood saws. When you push a thin piece of metal against resistance it can flex or bend (Western saw). The mechanics of exerting force when you pull (Japanese saw) does not have that problem. So the design of the KSG bolt carrier it fine for using the forend to “pull” the bolt and cartridge into the chamber where it gets locked in by the bolt. But to extract the round the skinny arms of the bolt carrier have to ‘push’ the rest of the bolt carrier, bolt, and round out. If the round is in tight the arms could flex or bend. Once that happens the alignment into the rails in the stick is off and cycling gets locked up.
 

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OK - a little science and research today about KSG failing to extract and possibly bending the bolt carrier. No shade - the KSG is broken down, trigger group is totally off, no bolt or bolt carrier - just the chamber and barrel. But these are live, unfired rounds

Taking several different brands and caliber of shells, some high brass and low brass, and even some Aguila mini-shells. Federal buck and slugs, Rio buck, NSI buck, Sterling #5 shot, and my dummy rounds. All slide in to and out of the chamber very easily - no force. I’m sure the plastic shell (and maybe also the brass) expands and is fatter (and clearly longer) after being fired. But still easy in is likely to be easy out.

However not the last shell - a Sterling slug. This would not slide into the chamber without some coaxing, and required a little prying to get it out. Sterling is made by Turaç in Turkey, to CIP specs. Not sure if the specs in this batch were off, or ooor quality control, or CIP is allowed to vary or different compared to SAAMI specs.

So failing to extract might occur if the shell is tight (especially right after firing when hot and most expanded) which can lead to a double load.

Finally, when cycling the KSG, the forend is pushing the bolt carrier back. If there is excess resistance with a shell tight/stuck in the chamber you end up using the two skinny carrier arms to push the bolt against additional resistance to extract a tight shell. This could lead to failure (bending, cracking) of the bolt carrier arm the point of connection to the carrier plate. The mechanics seem similar to comparing Western vs. Japanese wood saws. When you push a thin piece of metal against resistance it can flex or bend (Western saw). The mechanics of exerting force when you pull (Japanese saw) does not have that problem. So the design of the KSG bolt carrier it fine for using the forend to “pull” the bolt and cartridge into the chamber where it gets locked in by the bolt. But to extract the round the skinny arms of the bolt carrier have to ‘push’ the rest of the bolt carrier, bolt, and round out. If the round is in tight the arms could flex or bend. Once that happens the alignment into the rails in the stick is off and cycling gets locked up.
Good analysis and I think your conclusion is exactly right. I have two KSG bolt carriers with cracks at the welds bonding the arms to the bolt carrier plate. That is the point that is going to take the brunt of the flex. I have not had this problem with the two KS7's that I have and they have seen their share of foreign ammunition. I note that the configuration of the KS7 bolt carrier is different. I has a "bracket", for lack of better terminology, at the other end of the arms that may reduce the flex in the arms. I note that the KelTec website store indicates that the KSG bolt carrier is out of stock and has been for weeks. I suspect that this problem has created a real demand for that part. A few years ago, a company was posting on a different forum that they were going to start manufacturing an improved bolt carrier for the KSG /but I don't see where that ever came to fruition. If you haven't given the KS7 a go, I think you'll be quite pleased.
 
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