WTF has gone wrong with my can?

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Conqueror
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WTF has gone wrong with my can?

Post by Conqueror » Mon Sep 29, 2014 4:39 pm

Weapon: CZ455 American. Has been chopped to 16.5" and threaded by ADCO with perfect, concentric threads.

Silencer: Liberty Sparrowhawk

Background: I use this combo frequently for squirrel hunting and target shooting. The rifle is a laser beam at squirrel hunting distances and I am used to ragged hole groups from 25-50yds using good ammo. The rifle's favorite ammo is either Wolf Match or CCI Green Tag; typically there is no substantial POI shift with this silencer and it still shoots ragged holes with the can onboard.

The problem: I went to the range today and couldn't hit a goddamn thing with the silencer installed. The picture below has two groups, both with the same point of aim (the target's center) using CCI Green Tag Competition, with a bipod and rear bag. The right group is what I'm used to, a single ragged hole just to the right of the POA. The silenced groups were atrocious, this is the best one and it's still 5-6x as large and has a huge POI shift with horizontal stringing. I can't figure out why. As I noted, the threads are perfect and this combination has been used many times before without issue. There is no evidence of a baffle or endcap strike. This occurred with 5 different brands of ammunition; CCI gave the best results, but with federal bulk pack the silenced groups were on the order of 25MOA. Magazine was the same. The silencer and its endcaps are snug. The can was cleaned and refinished by Liberty recently but has been used since then and did fine. The only thing "unusual" is that it was raining at the range today and I usually shoot in nicer weather.

Someone wanna help me troubleshoot? I feel like I have checked all the normal reasons for a normally reliable suppressor to suddenly group for s--t, and come up empty. If I can't find an issue with my setup this thing is gonna go back to Liberty for an inspection.

Image
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Historian
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Re: WTF has gone wrong with my can?

Post by Historian » Mon Sep 29, 2014 5:32 pm

Did you log the order that the holes were made? For example
looking at target did you get the three on the right together and
then the two at the left drifted. Was the weapon rigidly held the
same way? Or did the holes alternate?

What is the geometry and diameter of the barrel's shoulder in back of
the threads? For example on the Bully barrel* the can has a robust perpendicular
face to firm against. On some pistols the can screws back until it runs out of threads
and this would introduce misalignment.

And of course there could be some asymmetries in the diameters of
the cans 'Pringles Potato Chip Ridges' - e.g., burrs.

Is it possible to show close up of the barrel threads, can disassembled, line
of sight through the can?


* << http://www.rimfirecentral.com/forums/sh ... %2B+barrel >>
Ninth picture down.

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Re: WTF has gone wrong with my can?

Post by doubloon » Mon Sep 29, 2014 7:53 pm

It seems you have eliminated a majority of the usual variables ... rain ... ammo ... etc.

What's odd to me is the majority of the difference between those two groups is horizontal. The vertical is tolerable if not ideal.

Since it's not spraying wildly the only thing that comes to mind is pushing/pulling the trigger but for some reason only with the suppressor mounted or if perhaps your last maintenance routine resulted in not entirely and properly securing the action to the bed so that maybe the weight/harmonics of the can is causing a bit of a wiggle when shot.

The whole left/right thing is bizarre to me and suggests something habitual or mechanical in nature.
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Re: WTF has gone wrong with my can?

Post by Conqueror » Mon Sep 29, 2014 8:20 pm

Historian:

1. The holes were not made in order, it was all over the map.

2. The rest of your theories would make some sense if this was a new can or a new rifle. But as I noted, this combo has been flawless for me for several years. There is nonissue with the shoulder, etc. (or if there is, it has been the same from day 1 and normally works fine).

Doubloon:

1. I've seen plenty of cans have horizontal POI shift, but not when they previously had none.

2. There is no pulling of the trigger. First of all it would make no sense that I would only pull the trigger with a silencer attached. And second of all, I routinely shoot much much farther, I am confident in my technique at 25 yards. :-)

3. There has been no maintenance since the last range outing. A month ago it was drilling 200yd steel with boring ease, then it went in the safe, now it won't stay on a paper plate at 1/10 that distance.
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Re: WTF has gone wrong with my can?

Post by Bendersquint » Mon Sep 29, 2014 9:01 pm

How does the threads and shoulder look on the host?

I ran into a similar issue with our 22lr can on my 77/22, turned out to be a small chunk of something between the rear of the mount and the shoulder of the host, wiped it off a tack driver again.

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Re: WTF has gone wrong with my can?

Post by Brittsc » Mon Sep 29, 2014 9:59 pm

I probably know less than anyone here, but I recently had a similar issue, but to a greater degree. I have a custom built heavy duty suppressor for my 8.5" AR 15. I primarily shot it on my 8.5" AR 15 with incredible accuracy, but decided to use it on my 14.5" AR upper more, cause I wanted to use my AAC Ranger2 on my Bolt gun, anyway.... On the 14.5" it would bulls eye first shot every time, then the next shot after that would be high and right about 5-6" with each following shot moving right about 1" or so. Took it back to the gentleman that built it and we thought we could see a shiny spot on the end cap exit hole but wasn't 100% sure. Not sure what he did, bored out minute amount? But now it is back to extremely tight groups with both length uppers. Wasn't having key holing or anything crazy, just a change. It had not previously done this with the 14.5" upper, but I did not shoot it that often on that upper until recently. I hope you get an answer soon. This would be very frustrating.

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Re: WTF has gone wrong with my can?

Post by FarmDadCO » Mon Sep 29, 2014 11:52 pm

Ill vote with Bendersquint as a most likely issue , crud on the shoulderof the barrel or suppressor mount . The other thing that comes to mind ( and it could be wrong as i have no experience with that can ) would be basically the same issue with the can endcap(s) allowing the baffle to shift a bit possibly creating a rub or strike .

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Re: WTF has gone wrong with my can?

Post by doubloon » Tue Sep 30, 2014 7:53 am

Conqueror wrote:...
Doubloon:
...
Yeah, I was taking a shot in the dark.

Agreed horizontal POI shift is not entirely uncommon but usually it shifts once and stays there not back and forth like the wide, flat string in the picture.

The string in the picture would make more sense vertical, then it would more likely be an ammo velocity issue.

Crud on the shoulder or a misaligned end cap is a better guess.
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Re: WTF has gone wrong with my can?

Post by Conqueror » Tue Sep 30, 2014 5:08 pm

I've seen heat cause horizontal stringing issues (ie one part heats up faster, expands more and causes stringing). But seems unlikely that it would occur out of the blue.

As others suggested, I re-inspected the shoulder and read endcap for any dirt/burr/crud. There wasn't really much, just the standard amount for a suppressed rifle. I did go ahead and give the shoulder and endcap a decent cleaning just to see. I'm now away on business so it'll be a bit before I can get to the range again. Liberty responded to my email and offered to inspect the can; if it still has issues when I get home I will send it to them for a checkup.

Maybe they can upgrade it to an Essence for me while it's there (hint hint Dave 8) ).
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Re: WTF has gone wrong with my can?

Post by Mageever » Tue Sep 30, 2014 5:29 pm

OK, here are mine:

-Junk built up on a normally tight (but just barely OK) thread relief will knock it off axis. Also, make sure the distal end of the muzzle isn't bottoming out on junk in the can.

-Your core is bent from a hard removal when super dirty.

-You have some lead fouling in the barrel that's affecting it enough to contact a baffle or just get close enough to have gases affect the flight. I've literally had a chunk of lead stuck in my barrel before that threw the bullets a foot of target. Thanks you Remington ammo.

Few people believe it, but look down the barrel from the chamber side to look for misalignment. If you look across the bore line from side to side and up and down, you'll see more of the dark silencer bore from one direction if misaligned. You can discern a few thou' doing this.

Best of luck!

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Re: WTF has gone wrong with my can?

Post by Conqueror » Tue Sep 30, 2014 9:18 pm

Those are beginner moves man. 8)

Core is not bent, alignment looks good. I actually never remove the core since Liberty cleans it for free. I just send it in every 10k or so. Only reason I posted is that I went through everything I normally tell people in this situation and struck out.
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Re: WTF has gone wrong with my can?

Post by chrismartin » Tue Sep 30, 2014 10:45 pm

Also, don't forget to inspect and clean the threads and end cap on the Liberty. Just as the shoulder and threads could cause an issue, so could the end cap on the liberty.

Just grasping at straws here. :)

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Re: WTF has gone wrong with my can?

Post by Mageever » Wed Oct 01, 2014 1:30 am

Conqueror wrote:Those are beginner moves man. 8)

Core is not bent, alignment looks good. I actually never remove the core since Liberty cleans it for free. I just send it in every 10k or so. Only reason I posted is that I went through everything I normally tell people in this situation and struck out.
Yeah, I forgot I was going to write in there a caveat that I know you're a smart dude, but just in case cover the basics... :D

My next thought revolved around what chrismartin said. I wonder if it's the back cap doing something weird.

When you have time, check your alignment down the bore and let us know. If it's perfectly aligned, maybe one of the two set screws that holds the barrel on is loose and the weight of the can is enough to whip it a bit.

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Re: WTF has gone wrong with my can?

Post by Conqueror » Wed Oct 01, 2014 12:43 pm

I did remove both endcaps and checked them, no bullet rubs and the threads looked clean. With my low-mount optic I can't completely pull the bolt without removing the eyepiece of the scope but the alignment seems as good as I can determine.
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Re: WTF has gone wrong with my can?

Post by 1911rocks » Mon Oct 06, 2014 8:19 pm

Have you tried removing the can and firing the same ammo?

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Re: WTF has gone wrong with my can?

Post by doubloon » Tue Oct 07, 2014 6:36 am

1911rocks wrote:Have you tried removing the can and firing the same ammo?
I thought that's what was represented in the picture in the first post.
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Re: WTF has gone wrong with my can?

Post by Conqueror » Tue Oct 07, 2014 10:23 pm

Yes, that is what is pictured. It was the same with multiple brands of ammo as well. I have been away on business for the last couple of weeks, but I will be back this coming week and will try again at the range.
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Re: WTF has gone wrong with my can?

Post by LawBob » Tue Oct 14, 2014 10:28 pm

You have lead build up in the barrel

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Re: WTF has gone wrong with my can?

Post by doubloon » Tue Oct 14, 2014 11:41 pm

LawBob wrote:You have lead build up in the barrel
Heh ... :mrgreen:

Is this the new "2 weeks"?
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Re: WTF has gone wrong with my can?

Post by Mageever » Wed Oct 15, 2014 1:18 am

doubloon wrote:
LawBob wrote:You have lead build up in the barrel
Heh ... :mrgreen:

Is this the new "2 weeks"?
Conqueror's gonna need a sweater vest. :D

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Re: WTF has gone wrong with my can?

Post by Conqueror » Fri Oct 17, 2014 9:20 am

LawBob wrote:You have lead build up in the barrel
Is this a joke?


To the others: Liberty has the can now, just got an email from them this morning that they are looking it over. It was the same story on the second range trip after thoroughly cleaning everything.
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Re: WTF has gone wrong with my can?

Post by doubloon » Fri Oct 17, 2014 4:51 pm

Conqueror wrote:
LawBob wrote:You have lead build up in the barrel
Is this a joke?
...
There was a different long thread with a lot of theories about accuracy issues with a particular 22lr.

IIRC it panned out to an early suggestion of possible lead buildup but not until after many other guesses where chased in its stead.

In this thread it's a joke.
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