Rifle + suppressor = problem

[PennsyPlinker]

I figure I will start here in this forum. I have a CZ 452 American and an SWR Spectre. The CZ was threaded last winter for the can. I was out doing some plinking suppressed for the first time, and could not come close to hitting anything. I thought maybe I had bumped the scope getting it out of the safe or something. So I took it back to paper.

In very short order I had the gun dead on at 25 yds (I had messed with the settings trying to fix it earlier on). I started there figuring I had to be close since it was off so bad. But it did not take long to get a bunch of holes all touching or close to touching. Then I screwed the can back on. I did not get any more holes in the paper.

To make a long story a little shorter, I was able to use two targets and measure the impact. I was still getting nice tight groups, but they were now hitting the paper 12" high and 4" to the left with the can installed! This was consistent with the impacts I was getting while plinking. Take the can off, and the point of impact returned to the bullseye. Put the can back on and back to the above 12" high and 4" off.

There are no baffle strikes on the can. I inspected the baffles, plus I ran about eight rounds through just listening. Nothing. I tried screwing the can down tight, and I tried snugging it down just enough to keep it from wobbling around. Nothing changed.

I have three handguns and two other rifles that play host to this can, and none of them have shown the same problem. Does anyone here have an idea of what I might check next, or what I might need to do to fix this problem? Please do me a favor. If you have experience, I would love to hear about it. If you are just going to engage in idle speculation, do that in someone else's thread.

Thanks.

[bac0nfat]

Have you checked to see if the threads are concentric with the bore? For starters you can look down the barrel with the suppressor attached and shine a bore light down the other end. After you make sure it's unloaded, of course.

[bogey1]

That will happen (sometimes) depending on caliber. Something to do with pressure in the can. (I think thats what i was told).
I use my gemtech halo (223) on my .22 bolt. Its dead on with or without the can. I never really tried hitting anything with it on my ar15.

If you can zero it in with the can on and it stays consistent, your ok. the only problem is when you remove the can, your screwed again. That would piss me off though.

[red dog]

i have a ar that changes poi when i install a can. but i have to admit not as severely as what you are experiencing. i attribute my issues to the additional weight on the end of the barrel. as you guessed mine with can shoots lower. may i suggest a peel washer when you install the can and try indexing said can and see if you can change poi.

[PennsyPlinker]

Have you checked to see if the threads are concentric with the bore? For starters you can look down the barrel with the suppressor attached and shine a bore light down the other end. After you make sure it's unloaded, of course.

I do not have a tool to check to see how concentric they are, but suffice to say, if there are no baffle strikes I can't see why it would be an issue. It may be, but no one has pointed out the reasoning or the mechanics involved.

As for changing the point of impact, yeah, I could accept that, except that it does not happen for any of my other hosts, and for this one it is not so much of a change of impact as it is the bullet coming out of the barrel and turning left and up - dramatically. This far off at 25 yds equals several feet at 100 yds. And that is what I was experiencing. If I had not been shooting into a very large hill, I would have never even been able to determine where the rounds were going at the beginning.

[FNG19]

I do not have a tool to check to see how concentric they are, but suffice to say, if there are no baffle strikes I can't see why it would be an issue. It may be, but no one has pointed out the reasoning or the mechanics involved.

Would you consider running a plastic rod from the barrel to the muzzle with the suppressor on to see if the rod has trouble getting all the way through? It seems to me that if the threads weren't cut right, the rod would have a hard time getting through the suppressor from the breech end of the rifle because of the angle it would have to proceed through.

452 barrels are a tight fit. That rod is not going to have any room to move if it has to change direction. Just make sure the rod has enough length to go down the entire barrel, through the entire suppressor, and have enough excess length to enable you to pull it back through the breech if need be.

This suggestion is a guess. I've never done it and don't know if it's a good idea or not. It does seem like one way to see what the story is.

Oh, here's another idea: Clamp the gun down and screw on the suppressor. See if you can tell if it's rotating about a different axis than the center line as you do so.

[forceinPA]

Try some diffrent ammo and see what happens. This can occure from time to time for a few reasons. Last resort call SWR the CS is awsome. A few 100'ths off on the threades can cause this with out a baffle strike, just keep an eye on it.

[bac0nfat]

I do not have a tool to check to see how concentric they are, but suffice to say, if there are no baffle strikes I can't see why it would be an issue. It may be, but no one has pointed out the reasoning or the mechanics involved.

As for changing the point of impact, yeah, I could accept that, except that it does not happen for any of my other hosts, and for this one it is not so much of a change of impact as it is the bullet coming out of the barrel and turning left and up - dramatically. This far off at 25 yds equals several feet at 100 yds. And that is what I was experiencing. If I had not been shooting into a very large hill, I would have never even been able to determine where the rounds were going at the beginning.

Your baffle openings are larger than 22, probably closer to .275". I just measured the opening in the end cap of my tac65 and it's .280". So it's entirely possible to have non-concentric threads and not have any baffle strikes. Especially if the center line of your bore and the center line of your threads are parallel, but not perfectly lined up; you could be off a great deal before you have baffle strikes. It could be off by about .025" before you get a baffle strike, and do you think that would change the POI? You are practically scraping on side of the baffles and .050" away from the other side.

And the fact that your can doesn't do this with other guns just tells us that you can is fine, but it doesn't tell us anything about the threads on your 452.

[normanvin]

Could this be an issue of the barrel flexing due to the added weight on the end of the barrel? Maybe the stock needs to be bedded to add more support to the barrel?

[knight0334]

Could this be an issue of the barrel flexing due to the added weight on the end of the barrel? Maybe the stock needs to be bedded to add more support to the barrel?

Yes on both. It is very possible that the suppressor has messed with the harmonics of the barrel. The added weight could have the barrel bending down on the stock.