KelTec Su16a-- Can't make it run, thoughts?

VinceDrake

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So as the title suggests, I've got what appears to be an early Su16, with the bipod, etc. Got it out of an estate, with the requisite lack of history that goes with that. Appeared not to have been fired very much, if at all.

I can't make this thing run. Kind of embarrassing, in fact.

No matter what I do to it, the centre of the primers in fired ammo blows out, jams itself into the bolt somewhere, blows the magazine out, big cloud of smoky goodness.

Have stripped it down to nuts and bolts, cleaned and lubricated everything. Firing pin is in nice shape, not broken damaged, bent. Tried many different flavours of ammo and magazines, Double and triple checked, to make sure I had it assembled correctly. No dice.

Using the masking tape trick, headspace appears to be in order. With live ammo, bolt locks into battery, as witnessed through the indicator.

Gas port lines up nicely with the piston, piston is not binding in the gas block.

I'm completely and utterly out of ideas-- Anyone got any suggestions as to what I am missing?
 
Check the bolt face, if there is a big hole where the firing pin comes out you have a problem. I currently have a bolt head on my keychain (from an su16) with that precise feature lol

You might have to contact vault distribution and see if they will warranty the rifle.
 
Thanks for the help!

I have checked headspace, it appears to be less than .006"

Mr. Driller: there's something interesting there-- The tip of the firing pin, does seem small for the hole in the bolt head, Did they do a run of incorrectly machined bolts or something?
 
Thanks for the help!

I have checked headspace, it appears to be less than .006"

Mr. Driller: there's something interesting there-- The tip of the firing pin, does seem small for the hole in the bolt head, Did they do a run of incorrectly machined bolts or something?

No, they start out normal and then blow out for some reason which causes the bigger hole. It is unsafe. I recommend contacting vault for warranty or at least to get a replacement. Replacing the bolt head would be very straight forward.
 
Check the bolt face, if there is a big hole where the firing pin comes out you have a problem. I currently have a bolt head on my keychain (from an su16) with that precise feature lol

You might have to contact vault distribution and see if they will warranty the rifle.

Exactly this ....Had one the same, you need a new bolt.
Vault Distribution sent me new one. I was the original owner, cured the problem.
 
No matter what I do to it, the centre of the primers in fired ammo blows out, jams itself into the bolt somewhere, blows the magazine out, big cloud of smoky goodness.


From the description given. DO NOT fire that rifle any more until you have it looked at by a gunsmith or replace the bolt.

Sounds like the bolt is the problem, you're very lucky nothing bad has happened yet.

This is a very dangerous situation and should have set off alarm bells in your head telling you to stop shooting the rifle.
 
From the description given. DO NOT fire that rifle any more until you have it looked at by a gunsmith or replace the bolt.

Sounds like the bolt is the problem, you're very lucky nothing bad has happened yet.

This is a very dangerous situation and should have set off alarm bells in your head telling you to stop shooting the rifle.

Got it. Yup. Have been exercising due care and attention since problem manifested itself. Remote firing in highly controlled circumstances, in a location unable to cause injury to myself or others. That being said, I would say the same thing so anyone else, so thanks, I appreciate it.

That all being said, Mr Driller, and Mr 73582, I took the rifle apart again this morning, and yup, I can stick the firing pin in the bolt head backwards. (i.e. from the front face towards the rear of the bolt.) Yup, that's a problem. I never would have thought a bolt face could erode, or blow out that much. Thank-you for the tip, and your time.

Thank-you gentlemen! New bolt, firing pin, and recoil spring ordered. (If I have to order, might as well get everything, right?)
 
Got it. Yup. Have been exercising due care and attention since problem manifested itself. Remote firing in highly controlled circumstances, in a location unable to cause injury to myself or others. That being said, I would say the same thing so anyone else, so thanks, I appreciate it.

That all being said, Mr Driller, and Mr 73582, I took the rifle apart again this morning, and yup, I can stick the firing pin in the bolt head backwards. (i.e. from the front face towards the rear of the bolt.) Yup, that's a problem. I never would have thought a bolt face could erode, or blow out that much. Thank-you for the tip, and your time.

Thank-you gentlemen! New bolt, firing pin, and recoil spring ordered. (If I have to order, might as well get everything, right?)

Nice good work. Simply fixing the problem instead of having a tantrum like most on here. Keep it classy!
 
See if you can go the warranty route...they offer lifetime transferable warrrentys on all their stuff....not sure if it covers the GEN 1 or not but always worth a try for sure!
 
Got the parts in the mail this morning, and yup, the face of the replacement bolt assembly makes a lot more sense than the original. Just enough space for the tip of the firing pin to protrude. Unlike the original.

If it helps anyone now or in the future, the diameter of the firing pin hole in the new bolt is approximately .045" *NOT* .100" I would estimate maximum firing pin projection about .015"

I'll assemble it tomorrow, and shoot it Saturday, but for now, I would say, yup, that's different. As an aside, I'll take a head-spacing before and after, just for interests sake. *Theoretically* is should be a drop-in part, but let's be smart about it, Right?

On a side note, Bernard (sp?) from Vault had the parts in the mail the next day. Really painless. Under $100 with firing pin and recoil spring.

Again, Thank-you Driller and Numbers! I wasn't even looking in the right place, until y'all posted!

Obviously, will post with results, but I can pretty much with 95% certainty call it fixed.
 
Got the parts in the mail this morning, and yup, the face of the replacement bolt assembly makes a lot more sense than the original. Just enough space for the tip of the firing pin to protrude. Unlike the original.

If it helps anyone now or in the future, the diameter of the firing pin hole in the new bolt is approximately .045" *NOT* .100" I would estimate maximum firing pin projection about .015"

I'll assemble it tomorrow, and shoot it Saturday, but for now, I would say, yup, that's different. As an aside, I'll take a head-spacing before and after, just for interests sake. *Theoretically* is should be a drop-in part, but let's be smart about it, Right?

On a side note, Bernard (sp?) from Vault had the parts in the mail the next day. Really painless. Under $100 with firing pin and recoil spring.

Again, Thank-you Driller and Numbers! I wasn't even looking in the right place, until y'all posted!

Obviously, will post with results, but I can pretty much with 95% certainty call it fixed.

Ironically the new rifle I got has this issue. New parts in the mail as well.
 
Plastic fantastic, wont be so wonderful when she blows. I don't care what others may say, Kel Tec do not make durable guns, keep a keen eye after replacing that bolt.

The RFB and KSG I owned seemed like decent quality and even though many complained about the plastic they had metal where it was needed. The RDB is probably very similar but when you drop down to the sub2000 and SU-16 rifles you really see the quality drop. The Sub2000 I used to own was a piece of crap but it did work, the few SU-16's I've played with were also junk except for the FX model that looks a lot more like an AR, it felt much better built.
 
I just thought I would drop a line, to finish the inquiry:

Yup, works fine with replacement bolt. No issues, no malfunctions. Would have been nice if I had remembered to bring more than 1 magazine with me this afternoon, but yeah. :D

50 rounds down range, the slow way. Decent grouping, no explode-iness, consistent ejection, problem solved.

Again, many thanks all! I don't know that I ever would have thought to look to the bolt head, without y'all's help.
 
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