Suppressors - first round impact shift

[Bowfinn]

My DD Enticer S doesn’t show any of these problems with my 6.5 prc. In fact my precision has improved with it on vs off, but I think that’s recoil and muzzle blast reduction. I’m hoping to get it on the tikka 223 in a month or so. I’ll report back if I experience any weirdness but I’m not expecting it.

 

[thinhorn_AK]

I shot the LTI this morning, no issues on 2 different rifles, small sample size but it worked as it should on a Seekins havak element 6.5c and a tikka 30-06.

I like it less than my TBAC ultra 7 and my scythe but more than my banish 30. That’s for another thread though.

 

[ztc92]

So I have an update and I’m now even more confused. In short, I went to the range today and shot very controlled off a bench with front/rear bag and found that the 223 had no issues but once again the 6.5Creed is showing a different POI with my first shot vs the next 3+.

Here’s the long version. My setup is two nearly identical tikka T3X lites, the first is .223 and the second is 6.5Creed. Both are set up with the Xeno Xero muzzle device and my suppressor is a harvester evo with the Xeno adapter. I used direct thread with 0 issues until this summer at which point I decided to try the Xeno system as I built an AR that used this muzzle device.

With the 223 and my suppressor today, I had zero issues. I re-zeroed with hunting ammo today. First picture is initial 5 shot group. Moved D0.1 and R0.1, shot group in second picture. Moved D0.1 further (so D0.2 total). I then proceeded to remove and re-attach the suppressor between each of the next 5 shots and shot the group on the third photo. Clearly no issues with the Xeno system on the 223 and it appears very consistent when removed and reattached.

Move on the to 6.5, do the same thing hoping won’t see any POI shift and I can blame what I saw last time on me, the shooter. This was the same 130 TMK load as last time I posted in this thread. First shot is marked for all groups with blue arrow in photos 4-7. The first three targets are 3 shot groups and between targets I allowed the can to cool to where it was just warm and could be easily held. For the last target I shot 5 total to see if it was still grouping well (I usually shoot this rifle with about 2” 10-shot groups prone off a pack so had hoped for this or better off a bench with bags. Similar to last time, most groups with the TMK’s appear to have a first impact that is 1.5-2” high and left, then the next shots all group fairly well. The last 5 shot group did not show this pattern but the other three did, as did multiple targets from last range session where I shot 10 shot groups.

I’m going to remove the Xeno system and try both rifles with direct thread adapter tomorrow. I’ll be sure to provide updates. As an aside, I did check scope rings, scope mounts and action screws afterwards to avoid other variables. Scope ring/mount were good. I found action screws were torqued to more than 45 but not quite 65 inch pounds. I have since added new loctite and torqued to 65 in pounds so that won’t be an issue next time.

Edit - Added photos

 

[ropeup79]

No scope adjustments with the 14 6.5 shots, correct? If you overlay those impacts it looks like a 2.5 moa group? Might have a bigger cone of fire than you thought.

 

[ztc92]

No scope adjustments with the 14 6.5 shots, correct? If you overlay those impacts it looks like a 2.5 moa group? Might have a bigger cone of fire than you thought.

Yes that is correct. Usually a 1.5” rifle off a pack, would expect that or better off a bench. Here is the photo I shared last week, note all groups would be 10 shot 1.5” or better if not the for the first shot being high and left. That’s what led to more testing off a bench tonight.

Edit for clarification: I did adjust scope on these groups as I was setting zero for TMK hunting load.

 

[ztc92]

No scope adjustments with the 14 6.5 shots, correct? If you overlay those impacts it looks like a 2.5 moa group? Might have a bigger cone of fire than you thought.

I did attempt to measure the group by superimposing all shots and you’re correct it was roughly 2.5” for 14 shots.

 

[ropeup79]

Definitely weird.

 

[ropeup79]

I’m pretty new to suppressors, but maybe an alignment issue when cooled vs warm or extra weight from can causing barrel to stock contact when cool?

 

[ztc92]

I’m pretty new to suppressors, but maybe an alignment issue when cooled vs warm or extra weight from can causing barrel to stock contact when cool?

Perhaps, that is once theory. My stocks are factory tikka and barrel channel sanded liberally with a 1” socket to the point I can’t make it contact the barrel with pinching with my hand.

Interestingly, I messed with the Xeno system a bit and found that even if I tightened it to just “snug”, once I fired a shot (or multiple) and the suppressor was “too hot to grab” I found that the suppressor was VERY tight to the point it was hard to remove. Then once cooled off it could be removed with minimal effort. I wonder if the taper mount in the Xeno system is getting too tight and affecting harmonics or something.

 

[ropeup79]

Any way to switch mounts with the other rifle or are they different thread?

 

[hibernation]

Interesting stuff. Minor update for mine, I shot a little with the original rifle that showed issues and had more like a 1 MOA shift between 1st and second shots, but overall within the 1.5 MOA I'd expect from this rifle.

Put the can on a different rifle and showed some more issues. 5 shot group without the suppressor was ~1", 5 shot group with suppressor and same ammo was 3" and POI was 5-6" lower than unsuppressed. I know there's some change to be expected, but that seems pretty significant. 22" sporter profile barrel on a 6.5 CM Sauer 100, factory threaded 1/2-28.

Borescoped the suppressor the next day and saw some grazes on the baffles. Not outright baffle strikes, but definitely spots where a bullet appears to have made contact. I'm guessing one or more of these rifles are having issues with concentricity. Maybe it's made worse by thin barrels heating up, steel vs titanium heating up differently, leverage from a longer can, and/or the relatively thin barrel left from the 1/2" threading. Not really sure at this point.

 

[ztc92]

Well I’m happy to report that after switching back to a direct thread mount and ditching the Xeno system the rifle is back to shooting well with both 130 TMK and 130 ELDM. I’m not ready to blame the Xeno system 100% but that’s definitely the leading theory. I won’t be messing with the rifle/supressor or touching the Xeno system again til after hunting season.

I had multiple other shooters with large, unsupressed magnums to contend with and that made for a lot of gas and mirage so I wasn’t able to truly re-zero, however did shoot 8 total groups to ensure no sign of first round shift, which I never saw. Either way, I’m just glad it’s back to working well with hunting season so close!

Photos for reference:
- First 5 shots with TMK to re-zero.
- 5 shots after adjusting scope, some mirage from heat and other shooters.
- 5 more shots after adjusting again and letting it cool down. Pretty bad mirage on shots 4 and 5, which are the two low-right.
- Multiple 3 shot groups of ELDM to ensure no sign of first round POI shift. Still some mirage but overall shooting well and staying within a 2” cone.

 

[wapitibob]

This is how my night went. Over 100 rounds without issue, and it didn't come loose.
DD Lti

 

[thinhorn_AK]

This is how my night went. Over 100 rounds without issue, and it didn't come loose.
DD Lti

View attachment 774423

What the hell happened there?