[DaveNC]

Been a longggggg time since I posted. Anyway, been wanting a sub2k for a few years and finally picked up a new one. Took it to the mountain this weekend to give it a test drive runnng a an octane 9 suppressor. The first two shots from 30 ft didn't even hit the paper and I thought I heard and odd sound from the muzzle. I removed the octane and examined the baffles and noticed a small nick in the exit baffle which explains the odd sound and total miss of the target. I went on to run 100 rounds with no suppressor and the reddot sight was dead. I really like this weapon and so does the wife.

I've already sent keltec an email but was wondering if anyone else here had the same issue? On my way to work this morning the thought occurred that instead of bad threading on the barrel it could be the nut surface isn't 90 degrees to the barrel threads which I'll check tonight. Any thoughts?

 

[850sub]

We were getting members with this problem.
Keltec redesigned the front sight.
You should have the upgrade sight if you just bought it. Post a picture of it.
Oh, and contact Keltec. (Oh, I see you have.)

 

[DaveNC]

I'm curious about what was wrong with the front sight that would cause a can misalignment?

Do you any details?

These were out of stock and I got a notification from PSA that they got a shipment in so I would think mine would be the latest and greatest.

Thanks,
Dave

 

[850sub]

Do a search. There are discussions here that cover it. Basically there was a set screw to hold the front sight in place that would cause the sight to be slightly canted. This caused muzzle devices to be canted. They redesigned the front sight to have a lock nut to secure the sight and deleted the set screw.

 

[DaveNC]

Do a search. There are discussions here that cover it. Basically there was a set screw to hold the front sight in place that would cause the sight to be slightly canted. This caused muzzle devices to be canted. They redesigned the front sight to have a lock nut to secure the sight and deleted the set screw.

Mine does have the the lock nut so I guess this will be a keltec issue.

Thanks

 

[Bill G]

I just had my Gen 1 barrel threaded, and have fit it with my Tirant 45 suppressor. I have not fired it yet, and now you have me worried. I know it seems to be a Gen2 issue, but is anyone aware of any Gen 1 issues? Thanks in advance!

 

[850sub]

You should have no problems if is threaded square to the barrel.

 

[DaveNC]

Now that I know what the fix is I understand how this problem could occur again. The part of the sight facing the barrel should really be shimmed for proper alignment so that the sight base is forced to square it self against the shoulder of the barrel that should have been turned squarely on the CNC lathe. Relying on threads to give you a squared edge isn't the correct way to get a squared edge even with a locking nut. Depending on what keltec says I may fix this my self using the correct shims to obtain a proper fit of the sight to the barrel shoulder.

 

[jimboksg]

Yep! That's why I need some property in Arizona.:violin: I would love to have a suppressor. But the politician's in this state watch to many movies and cant distinguish fantasy from reality. That's an awesome suppressor you got.

Here is the one I would love to own. If it is even being made. I saw pictures and videos from a shot show and I love the concept.

It snaps on fast and easy . of course as most suppressors do it makes the Shot gun rather front heavy but it's cool none the less. :yahoo:

 

[DaveNC]

I heard back from Keltec and they provided a shipping label to ship the weapon back. I wanted to wait until I got my alignment rods to verify it was in fact a sub2k issue. Well it is and it isn't. The suppressor alignment is slightly off with the alignment rod in both the glock 19 and sub2k with the sub2k being slightly worse hence the end cap nicks. Looks like I'll be contacting Silencerco with the problem. Apparently the alignment has been off since day one but never caused a problem until I tried it on the sub2K.

 

[DaveNC]

It's not just the end cap that is misaligned. I took the end cap off while on the phone with Silencerco and measured two axis from the alignment rod to the side of the suppressor tube. One axis is off over .030 which is huge for something that is supposed to be centered and the 9mm bullets have barely been missing striking the baffles by about .010. Silencerco has already issued an RMA though so all is good with the world again.

Looking back now I was WAY to quick to blame Keltec without doing a real analysis of the problem. I should know better since I solve problems for a living. :booboo:

Regards,
Mr Anderson

 

[850sub]

DaveNC, where did you source the alignment rods?

 

[DaveNC]

McMaster Carr online for about $7 each. Part #8893k231 for 9mm, 8893k219 for 300 blkout and 8893k191 for 22lr.

 

[Squashracquets]

Seems like it would be a good idea after installing any barrel-end device to drop a bullet through the barrel or use a bore gauge to assure there is clearance. Conceivably any misalignment could be bad enough to be dangerous.

 

[WRBuchanan]

What you are experiencing is the effects of "Cumulative Error."

This means that the Individual Parts in your silencer are not all made dead on the "Nominal Dimensions" called out on the print. They are still inside the tolerances but not all dead on.

When they are assembled the tolerances add up to larger errors which affect the end result.

The other thing that can affect this is Male and Female threads being made to opposite ends of the tolerance. If there is no shoulder for the threaded parts to butt against, The threads will cock one way or another. If the threads are loose enough it will occur even if there is a shoulder, but the result will be Parallel Centerlines instead of Angled Centerlines. Neither one is desirable.

The ideal way to interface a silencer or other muzzle accessory is to have Steps on the barrel before and after the threads that correspond to ones in the accessory that are as close as possible to interference fit, like .001-.002 clearance between male and female fits. as long as the threads in the barrel and accessory are both concentric,,, perfect alignment will be there every time they are assembled.

The Germans figured this out about 1910.

Unfortunately it is not practical to do on a generic silencer made to fit a "brand of pistol." Each one has to be fit to a specific barrel.

Getting a silencer to work right on multiple guns is a pretty good trick.

Randy

 

[Bubbas308AR]

What you are experiencing is the effects of "Cumulative Error."

This means that the Individual Parts in your silencer are not all made dead on the "Nominal Dimensions" called out on the print. They are still inside the tolerances but not all dead on.

When they are assembled the tolerances add up to larger errors which affect the end result.

The other thing that can affect this is Male and Female threads being made to opposite ends of the tolerance. If there is no shoulder for the threaded parts to butt against, The threads will cock one way or another. If the threads are loose enough it will occur even if there is a shoulder, but the result will be Parallel Centerlines instead of Angled Centerlines. Neither one is desirable.

The ideal way to interface a silencer or other muzzle accessory is to have Steps on the barrel before and after the threads that correspond to ones in the accessory that are as close as possible to interference fit, like .001-.002 clearance between male and female fits. as long as the threads in the barrel and accessory are both concentric,,, perfect alignment will be there every time they are assembled.

The Germans figured this out about 1910.

Unfortunately it is not practical to do on a generic silencer made to fit a "brand of pistol." Each one has to be fit to a specific barrel.

Getting a silencer to work right on multiple guns is a pretty good trick.

Randy

Or as I have heard the term, "tolerance stacking". Same idea, just different words.

 

[DaveNC]

Well, I just received my suppressor back from Silencerco and it still isn't concentric on the Keltec barrel. They called me within an hour of an email I sent them with my concerns and walked me through verifying that the barrel isn't concentric. This particular suppressor has a fool proof way to check concentricity in that once threaded onto and locked onto the barrel the suppressor can can be turned 360 degrees by compressing the buffer spring in the first baffle and turning the suppressor about 20 degrees at a time. The 10:00 concentricity gap doesn't change even when rotating 360 degrees so back to keltec it goes. I wanted to verify the suppressor was good before sending it back to the factory. The Silencerco guy said if there are any problems with keltec fixing it he would help since worked with Keltec on this type of issue before.

 

[DaveNC]

Well I decided to fix it my self and it took maybe 15 mins. I have some precision shims used for timing a muzzle device. To verify my suppressor was true I screwed the suppressor snug on the muzzle and marked a spot on the suppressor and locking nut on the sub2k. I then used different thickness shims to walk the marked spot on the suppressor around the locking nut mark on the sub2k in about 20 to 30 degree increments using the alignment rod with each change in degrees. The 10 o'clock end cap nick location on the alignment rod never changed through about 300 degrees rotation thus verifying Silencercos evaluation. If the suppressor wasn't concentric the nick location would have changed and it didn't.

The fix was easy using a jewelers file, masking tape and sharpie. I taped the threads and starting filing on the 10:00 position on the front sight locking nut checking for proper concentricity with the alignment rod and using the sharpie to mark the nut to control the amount of material I removed. I watched the suppressor walk from being a end cap nick to almost perfect alignment! The suppressor is now concentric with the muzzle bore. I finished up with some cold bluing and all is well now

Silencerco basically stated that there should be a shoulder cut on the barrel where the front sight and locking nut squares up to it. The keltec front sight design doesn't have that and theres really no easy way to fix it. I'm ok with that and this weapon is a keeper.