Suppressors Puzzling Suppressed Groups - Updated report 5/6/12

[nfoley]

Okay, shooting this past weekend left me scratching my head.
Rifle is Remington 700 21" bbl with Gemtech HVT QD (and tensioning style adaptor).
First shot through cold (not clean) barrel and suppressor places first shot about 6" high at 100yds. Five shots after puts a 3/4" group right where it should be - 6" lower than first shot.
Now I REMOVE the suppressor and first shot goes right in with tight 5 shot 3/4" group. Next 4-5 shots makes 3/4" group up high again (6" high again!).
Hope that makes sense - I know pics would help but tossed my targets. I called Gemtech and they were puzzled also.
And there's more...
I put the same suppressor on my 14.5" POF and there is almost no change in POI between 1st and subsequent shots.
I know this sounds strange, but I repeated above several times after waiting about 20-30 minutes to let everything cool.
Any thoughts???
I have heard about using a can of compressed air (CO2 or N2- kind you use to clean computer stuff), and squirting down barrel then placing a piece of tape over barrel for first round. Anyone tried that?

 

[biffj]

Re: Puzzling Suppressed Groups -

The difference in barrel length between the two is probably one big reason for the change in POI. The shorter barrel will be less affected by the weight on the end of the barrel. The difference in barrel diameter and taper will change how they are affected by the suppressor. Work out tables for each rifle with and without the can on the end. I've seen the POI shift as pretty consistant with the same can. . .

Frank

 

[nfoley]

Re: Puzzling Suppressed Groups -

I probably didn't make it clear, but it is only the first shot with the suppressor on that has a different POI. I am going to try spraying some 'canned air' down the bore for the first shot this weekend per Ingel Ballistic Research's idea. Seems the idea is to displace the oxygen with an inert gas and simulate conditions which occur after first shot fired.

 

[redirt78]

Re: Puzzling Suppressed Groups -

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: nfoley</div><div class="ubbcode-body">
First shot through cold (not clean) barrel and suppressor places first shot about 6" high at 100yds.

Five shots after puts a 3/4" group right where it should be - 6" lower than first shot.


Now I REMOVE the suppressor and first shot goes right in with tight 5 shot 3/4" group.

<span style="color: #CC0000">Next 4-5 shots makes 3/4" group up high again (6" high again!).</span>
</div></div>Let me make sure we are reading this right.

1) First cold bore shot WITH can is 6" high.

2) The next 5 shots WITH can are bullseye.

3) Now you remove the can and shoot 1 shot in the bullseye.

The red part is where it gets confusing. Are you saying (in the red part) that

4) WITHOUT the can that those 4-5 shots are 6" high after the first shot WITHOUT the can that hit bullseye?

If that is what you are saying then the gun doesn't stay consistent even without the can on it.

I would check the action screws, scope base and ring screws... If that doesn't work then maybe the scopes internals are screwed up. Something is not right with the gun, mount, screws or scope if that can shoots fine on your POF and doesn't stay consistent WITHOUT the suppressor.

That's the way the red part I quoted from you reads to me. If that's not right then its confusing.

 

[redirt78]

Re: Puzzling Suppressed Groups -

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: nfoley</div><div class="ubbcode-body"><span style="color: #CC0000">I probably didn't make it clear, but it is only the first shot with the suppressor on that has a different POI</span>. I am going to try spraying some 'canned air' down the bore for the first shot this weekend per Ingel Ballistic Research's idea. Seems the idea is to displace the oxygen with an inert gas and simulate conditions which occur after first shot fired. </div></div>Sorry I didn't notice that before I posted.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: nfoley</div><div class="ubbcode-body">
Now I REMOVE the suppressor and first shot goes right in with tight 5 shot 3/4" group. Next 4-5 shots makes 3/4" group up high again (6" high again!).
</div></div> The way that part is written is confusing to me ^

 

[nfoley]

Re: Puzzling Suppressed Groups -

It would make it much easier to understand with pics and I will take some this weekend.
But after shooting suppressed I want to see where a five shot group goes unsuppressed.
So after removing suppressor, I shoot five shots. First shot hits different than following four. It is about 6" lower.
I find it hard to believe, but it did it several times.

 

[nfoley]

Re: Puzzling Suppressed Groups -

I will bring another scope with me. It could be something weird inside scope.
Action screws were torqued to 55 and rechecked. Scope rings and base screws also checked. I also mark my scope tube next to rings to verify it does not move.

 

[flounderv2]

Re: Puzzling Suppressed Groups -

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: nfoley</div><div class="ubbcode-body">It would make it much easier to understand with pics and I will take some this weekend.
But after shooting suppressed I want to see where a five shot group goes unsuppressed.
So after removing suppressor, I shoot five shots. First shot hits different than following four. It is about 6" lower.
I find it hard to believe, but it did it several times.
</div></div>

Based on what youve said. Im guessing its your form. Each of these times your POI changes appears to be directly after you get out from behind the rifle and change something. Have someone else shoot your rifle that is a good shot.
Sounds like you are not consistent on your first shot after getting out from behind the rifle.

 

[nfoley]

Re: Puzzling Suppressed Groups -

Interesting thought on form. Will have another shooter try shooting.
I will say I have never shot a 6" flyer before, and at times while shooting groups do come off the rifle.
But something has to explain this so am happy to try that as well.

 

[redirt78]

Re: Puzzling Suppressed Groups -

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: nfoley</div><div class="ubbcode-body">It would make it much easier to understand with pics and I will take some this weekend.
But after shooting suppressed I want to see where a five shot group goes unsuppressed.
So after removing suppressor, I shoot five shots. First shot hits different than following four. It is about 6" lower.
I find it hard to believe, but it did it several times.
</div></div>Yeah I can see why you are scratching your head, just doesn't make sense. Good luck man

 

[HPLLC]

Re: Puzzling Suppressed Groups -

A guy posting as Black-X on ar15.com had problems with his tension mount also.

It seems like maybe the tension mount might be prone to this sort of issue, or maybe a flawed installation (barrel thread issue) causes issues.

Gemtech would be the people to talk to. The picture below is from ADCO. They do great thread work and might have experience with the tension mounts and the ability to solve your problem also.

 

[Black-X]

Re: Puzzling Suppressed Groups -

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Griffin Armament</div><div class="ubbcode-body">A guy posting as Black-X on ar15.com had problems with his tension mount also.

<span style="color: #FF0000">It seems like maybe the tension mount might be prone to this sort of issue</span>, or maybe a flawed installation (barrel thread issue) causes issues.

Gemtech would be the people to talk to. The picture below is from ADCO. They do great thread work and might have experience with the tension mounts and the ability to solve your problem also.

</div></div>

The part in red is how rumors get started.

My issue was with the specific suppressor that I had. With just the tension mount I was getting very good groups, mostly 1/2 MOA with my FN SPR. Also POI shift was 1 MOA down when I installed the HVT and IIRC was quite repeatable.

I don't want to speculate but 6 MOA vertical spread and the way that it's happening seem to ME that there are bigger issues at hand with the rifle system. I could be totally wrong and probably am, but I say this because the OP's HVT works well on his POF but not on his bolt rifle. My issue occurred on 3 different rifles with both mounting systems (tension and Phantom) and that's how I isolated it to my specific can.

If there is a problem with the can or the mount I'm pretty confident that Gemtech will take care of it.

 

[nfoley]

Re: Puzzling Suppressed Groups -

I enlisted another ('good shot') to come shoot this weekend and will be trying another scope as well.
Oh, and I just received my manners T5 stock today with mini chassis so will have the rifle in that stock next shoot as well.
I did have someone suggest the longer barrel on my 700 would exaggerate any problems caused by varying gases in the barrel/suppressor.
I am trying to get in touch with gemtech's custom shop and see if they can help. So far gemtech has been very helpful and concerned.
Will post pics and updates when available, and appreciate much all suggestions. Thanks guys!

 

[redirt78]

Re: Puzzling Suppressed Groups -

The T5 w/ mini chassis and properly torqued action screws will eliminate the possibility of your problem being in the stock. I have the same one and it's great. Turned a 3/4 to 1 MOA factory Rem into a 1/2" gun or a little better depending on how I'm shooting (at 100).

 

[nfoley]

Re: Puzzling Suppressed Groups -

Quick update - range was packed so went to the desert to shoot steel and was getting MOA groups out to 600 yds AFTER first cold shot through suppressor. First shot still high. Had another shooter with exact same results.
Gemtech is pretty busy with Shot Show going on, hopefully will get in touch with them this week.
Didn't try the canned air cause the cans all say "flammable when used next to source of ignition." if inside a barrel isn't a " source of ignition" I don't know what is! Anyone ever tried this?

 

[biffj]

Re: Puzzling Suppressed Groups -

I don't think your canned air trick is going to gain you anything. First round pop is a problem with some suppressors and adding C02 can help remove that. Some guys use WD40, grease or some other coolant in pistol cal cans to help reduce the sound as well. Its not a good idea in a rifle cal suppressor due to a couple of reasons. One is hot gas flashing the liquid into steam and jacking the pressure well above what you've already got in the powder gasses. It can overstress things. The other is the gasses bouncing any liquid up into the path of the bullet which can deflect it into a baffle.
As far as your first round flyer the gas probably won't have any affect. Check your mount and try your can on a shorter barrel to get rid of that as a possible reason. Someone must have a shorter rifle with a threaded barrel....

Frank

 

[nfoley]

Re: Puzzling Suppressed Groups -

Frank,
Thanks for the info. Not gonna try the canned air.
I did use a different scope this weekend, made sure base was torqued on.
And I did put the suppressor on my POF 308 with 14.5" barrel. No problems with that rifle. My understanding is the shorter barrel has less of an effect. Was that your reasoning for trying shorter barrel?
The tensioning mount appears to be on well, but not sure how to check other than for tightness. It was threaded and put on the 21" remington 700 by a very competent smith. And wouldn't an improperly placed mount have more erratic results? This first shot high thing is VERY reproducible (from cold suppressor). Once it is warm no issues.

 

[Darkop]

Re: Puzzling Suppressed Groups -

I have a problem that is similar to yours. I do not wan't to hijack your thread to solve my problem but we might find a solution together.

I have a Remington 700 5R with work done to it. It shoots match ammo and my hand loads into .50"-75" (5 shot groups) with the vortex style Gemtech HVT adaptor. I also have a Gemtech Quicksand. When I install the can my POI changes 3.5 MOA to 5 O'clock and my groups INCREASE to 1.5-1.75 MOA. I have tried all sorts different factory ammo, all with the same result. I installed a friends Quicksand on my rifle and only had 1.25" POI change and groups in the 1.25 MOA area.

When I install this can on my Noveske N6 with 14.5" barrel the group size INCREASES but about 1 MOA as well, but only 1 MOA of POI change.

I sent the can back to Gemtech and they checked the runout and internals of the can and found everything within spec for it. They installed it on their base rifle of a Remington 20" SPS with Phantom style adaptor and shot a 3 shot group of about .50 MOA with a POI of 1 MOA @ 12 O'clock. When they sent the can back they included the target and the Phantom adaptor. I installed the adaptor and had the same results as I posted above. No change.

I'm very frustrated right now and haven't shot the can on any of my rifles in 8 months. I think the only thing I can do now is to try developing a new load to shoot specifically with this can installed. Other than that I'm at my wits end. I might consider having Gemtech change the can to a Sandstorm screw on style and see if that changes anything. It just doesn't make since to me to take a solid sub MOA rifle and turn it into a 1.5MOA gun with a suppressor!

THINGS I"VE THOUGHT ABOUT
- Quick detach cans have a little movement in them. Not good for precision shooting
- Even lightweight Titanium cans change the harmonic vibrations of the barrel on a rifle
- The spring loaded style mounting of the HVT/Quicksand might allow even more movement of the can during recoil, effecting group size
- The same style can by the same manufacturer can shoot differently, as shown when I installed a friends Quicksand on my gun

Can you burrow another HVT and shoot on your gun? it seems that you have eliminated any other cause of your problem IE: stock, scope, shooter

Good luck and I truly hope you find a correction to your problem.

Until that day,
Darkop

 

[nfoley]

Re: Puzzling Suppressed Groups -

Other thing I don't like about QD (and wish I knew before buying) is the blow back that escapes around the mount and back onto objective lens of scope. I am a little concerned about damage to lens coating over time.
Got my first response back from gemtech today. They suggested switching to thread mount. I really want to know this will fix the problem before I go spending more money. Will update as I hear back.

 

[rideHPD]

Re: Puzzling Suppressed Groups -

@Darkop I'm not intimately familiar with suppressor troubleshooting, but could there be a slight mismatch between the threads on your barrel and adapter/can or could they be over or under torqued? if the can isn't in-phase with the rifle's vibration that could be your answer

@nfoley What do your groups look like when you shoot w/o the can successively, ie not going back in forth between can and without? When you shoot the rifle without the can, what's on the barrel; thread protector/muzzle device/? Can you shoot the rifle with the barrel bare, ie with bare threads? That could eliminate the can as the source of error since you mentioned you have the inverse problem with the can and then w/o. What's your zero with bare threads? There was a post a little while ago where thread protectors opened up bare thread groups, which suggests phase discontinuity caused by the internal stress induced in the barrel by screwing down the MD. Your problem suggests slack threads and improper seating (ie first shot w/ or w/o seats/unseats whatever is on the muzzle? I could just be completely wrong but it's worth looking at.

 

[Darkop]

Re: Puzzling Suppressed Groups -

rideHPD
I did change out the Vortex style muzzle device to the phantom style. I tried three different torque setting. No change. Thanks for the input.

My next step is to try and develop a different load and see if that changes anything. Problem is that it's 3 degrees outside right now. If I develop the load now it might not work as well when warmer, not to mention it's hard to shoot well when that cold.

Until that day,
Darkop

 

[rideHPD]

Re: Puzzling Suppressed Groups -

Work up a load for cold and warm weather. Barrel harmonics are dampened by warmer weather and will change the conditions of the ideal round (the round needs to dissipate energy into the wavelength of the rifles 0th harmonic which depends on the metals crystal structure's ability to move around.

 

[nfoley]

Re: Puzzling Suppressed Groups -

rideHPD,
Interesting points. I will attempt to shoot with the bare threads and see what happens. Actually had the gunsmith (Keith from Phoenix Custom Rifles) suggest the same thing. It had not occurred to me the suppressor mount on the threaded barrel could have an effect, even without suppressor attached.
The rifle is at Manners right now - Tom graciously offered to look at the stock fitting of the T5 the rifle now sits in.
I appreciate all input and am confident the problem will be fixed.

Darkop,
I am also debating switching to thread on from QD. Only hesitation for me is I use it on a 14.5" barrel which needs the extra length of the adaptor permanently attached to keep it legal. May change barrel to 16", or get another tax stamp to make it an SBR. OR, I could go the expensive route and buy another suppressor (thunderbeast). On my POF 14.5" the gemtech HVT is perfect! No issues with it on that gun.

 

[nfoley]

Re: Puzzling Suppressed Groups -

Quick update. Gemtech got back in touch with me and are being very helpful. They have offered to switch the mount to thread on for no charge if problem persists.
Rifle should be back next week to shoot some more.

 

[Darkop]

Re: Puzzling Suppressed Groups -

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: nfoley</div><div class="ubbcode-body">Quick update. Gemtech got back in touch with me and are being very helpful. They have offered to switch the mount to thread on for no charge if problem persists.
Rifle should be back next week to shoot some more. </div></div>

nfley,
Good to hear. I take it you already sent it back? If not ask them if a stronger spring can be installed in the attachment point of the can, this might resolve your problem as well.

It has warmed up a little here so I did a "Work Down" on my 175g SMK load. My regular load, That shot 1/2"-3/4" W/O the suppressor was 45.4g Varget. I went down in .01 grain increments and shot 5 rd groups @100 yd. Lo and behold at 44.6 grains my groups "SHRANK" back to 1/2" I'm headed back out today to shoot several groups with and without the Can to make sure it wasn't just an anomaly. If so, then when it warms up above freezing, I can chrono again and start building dope cards again.

I'm optimistic again about this can.

Off to the range,
Darkop

 

[Hooper]

Re: Puzzling Suppressed Groups -

Member here: "Doorkicker" had a HVT and may have some feedback for you.

Some suppressor baffle designs will cause more POI shift than others. Some rifles will need to settle in after a suppressor is mounted.

Try this:
Shoot a consistent group unsuppressed.

Mount suppressor
Shoot a 5 shot group suppressed. Let cool.

Shoot another 5 shot group for mounting test. Let cool.

Take suppressor off.
Shoot a 5 shot group. Let cool

Mount suppressor.
Shoot 5 shot group.

Record results.


I have seen some rifles need more than 5 shots to settle in. It has to do with barrel harmonics and bedding stress.

If you got the same results between step one and two where you fired 2 suppressed groups, then it is not the mount. If you got a flyer on the first suppressed shot after mounting, and did not get it with the second suppressed group after cool down, then take them up on their offer and convert to thread mount.

One less variable.

 

[nfoley]

Re: Puzzling Suppressed Groups -

Rifle will be back this week. Will try your suggestion Hooper, thanks for the input.

 

[nfoley]

Re: Puzzling Suppressed Groups -

Took it to the range after work for a quick shoot at 100 yds. Still doing exact same thing.
I shot a 1/2" group initially, without suppressor.
Then let it cool completely. Attached suppressor and first shot went high. Rest of the group went into about 3/4".
And after shooting suppressed for around 20-25 rounds I noticed it would take a couple rounds (with suppressor removed) to settle the rifle back down and group well. This part I don't understand at all.
Will be taking rifle out to longer range this weekend if it isn't too windy.

 

[nfoley]

Re: Puzzling Suppressed Groups -

Here is a 4 shot group with the suppressor and 175 SMKs over 44g Varget. Best group of the afternoon. This was done after the initial 'cold' shot. The taped shots you can see were from 155 SMKs which didn't shoot well at all. As you can see it really has potential - if I could just get rid of that annoying 'first round flyer' I would be ecstatic.

 

[Darkop]

Re: Puzzling Suppressed Groups -

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: nfoley</div><div class="ubbcode-body">Here is a 4 shot group with the suppressor and 175 SMKs over 44g Varget. Best group of the afternoon. This was done after the initial 'cold' shot. The taped shots you can see were from 155 SMKs which didn't shoot well at all. As you can see it really has potential - if I could just get rid of that annoying 'first round flyer' I would be ecstatic.

</div></div>

Did you have to rethread your barrel, or did you just remove the tensioning muzzle attachment device?

I'm still trying to work out the problem with my Quicksand. If changing your Quicksand to thread mount didn't change anything I think Ill just keep mine the way it is and live with it.

Edited to add: Is your 1 round still 6 MOA high or did it change at all when you wen to the threaded can?

 

[Slickrick0999]

Re: Puzzling Suppressed Groups -

I have a Gemtech HVT thread on.
Makes a dag gum good .22lr can....

 

[nfoley]

Re: Puzzling Suppressed Groups -

Darkop,
I still have the QD, with tensioning style mount. Still getting the same first shot high problem. It is the HVT, not the quicksand.
I am still debating switching to thread on but will have to chop an additional 2" to get that (due to the tensioning mount thread).
The difference in the last shoot was the stock is the manners T5 with mini chassis and now free floted barrel, and I put a better trigger on the rifle.
Shot yesterday to 650 yds but the wind was terrible. Hard to get any meaningful data - groups were in the 10-12" range. Mostly just out putting more rounds through suppressor. (Lowlight had similar problem with a gemtech which got better with more rounds thru it).

 

[Slickrick0999]

Re: Puzzling Suppressed Groups -

My HVT has been getting better with more rounds thru it in all honesty.
Ran about 300 rounds of .22lr thru it also.

 

[Darkop]

Re: Puzzling Suppressed Groups -

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Slickrick0999</div><div class="ubbcode-body">My HVT has been getting better with more rounds thru it in all honesty.
Ran about 300 rounds of .22lr thru it also. </div></div>

Slickrick0999
How much better? groups tightening? POI reduction?

Thanks,
Darkop

 

[Slickrick0999]

Re: Puzzling Suppressed Groups -

Darkop,
I have to shoot it for some groups at 100 yards. The last few times I have shot it have all been 300 to 800 yards. My previous experience with it, I would have never thought it would have shot that far consistently. On 3 separate days it has been very repeatable and consistent. I am actually enjoying shooting it now.
I will post results as soon as I shoot it for groups. I am very interested in running it thru a chrono also. My initial trials showed it slowing my round down.

 

[nfoley]

Re: Puzzling Suppressed Groups -

Okay, finally an update. Had Gemtech convert the can to thread on. Placed the can on an 18.5" Savage 308 (which Phoenix Custom Rifles cut and thread for me - very nice work on their part) and went out to range today.
No more first round flyer. This is preliminary but I just wanted to get out and give it a quick try. Target below shows 2 shots high, adjustment made and then remaining 3 shots place in center of red.
Will take it out when I get a chance to some further distances but I am liking the results so far.

 

[JSTARSZ]

Re: Puzzling Suppressed Groups -

That is awesome...I am still waiting for mine to come back Gemtech. I have big plans for this suppressor and I hope it does as well as yours has. The QD mount just never worked for me and my rifles. It was just too unpredictable for first round precision. I don't think I could have ever used it for hunting as I just had no idea where the POI would land and I would wound an animal.

I just pray mine comes back and does the same as yours. Thanks for the update. That really makes me feel like I am not sitting with a useless stainless paperweight.

When I get mine back I will update the thread as well.

 

[LtDan]

Re: Puzzling Suppressed Groups -

Please post your results, my HVT QD is unusable. It has a significant POI shift and until the can gets hot, turns a sub MOA rifle into a scattergun. I also hate having a new, expensive paper weight.

 

[ncorry]

Re: Puzzling Suppressed Groups -

nfoley- was the recent shooting with the Savage the first time you'd tried it on a different bolt rifle than the 21" 700 you started with? It works on the Savage bolt and the POF AR, but just not on the 700?

 

[nfoley]

Re: Puzzling Suppressed Groups -

ncorry,
You bring up an important point. This time I was using a savage, last time it was my rem 700 (which is at Phoenix Custom Rifles now getting rebarreled - otherwise I would retry it).
It may have been the rifle.
And LtDan, I will post the pic of the group with the suppressor later tonight. Am hoping to do some 500-800 yard shooting this weekend and will update. I really need to shoot it more before I say too much, but this past weekend gave me hope! I was really hoping the I didn't buy an $800 paper weight!

 

[nfoley]

Re: Puzzling Suppressed Groups -

Well, took it out today to shoot out to 1000 yards. Not so good. Best I can say is it does okay. Biggest problem is consistency.
Would shoot a good group at 550 (never took it further because of inconsistency), then for whatever reason would be off the steel and require messing with the scope to get it back on again. Tried completely cooling between shots, shooting 5 rounds roughly 30-40 seconds apart. Just wasn't cooperating. And I just could not get any kind of consistent pattern for what it would do next. It did shoot great without the can, but again still takes about 6-8 rounds after removal of the can to shoot well.
As a 'control' I had a 24" AR15 shooting 77g SMKs and it was dead nuts on EVERY time from 100-550 yards, shooting several 3" groups at 550 yds.
Will try again another day, but am seriously thinking about scrapping the can for long range precision. Or buying a TBAC.

 

[JSTARSZ]

Re: Puzzling Suppressed Groups -

I am still waiting for mine to come back from Gemtech. They have had it over four weeks now and I am heading towards five. Kind of frustrating.

 

[nfoley]

Re: Puzzling Suppressed Groups -

One thing I will add is the POI change between suppressed and non-suppressed is the most I have ever heard of. When I screw the suppressor on the groups are almost 14 MOA high (yes high) at 100 yds compared to without. That is with the 18" Savage. Gotta be some kind of record!
When I had the QD on the 14.5" POF change was only about 3 MOA.

 

[JSTARSZ]

Re: Puzzling Suppressed Groups -

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: nfoley</div><div class="ubbcode-body">One thing I will add is the POI change between suppressed and non-suppressed is the most I have ever heard of. When I screw the suppressor on the groups are almost 14 MOA high (yes high) at 100 yds compared to without. That is with the 18" Savage. Gotta be some kind of record!
When I had the QD on the 14.5" POF change was only about 3 MOA.
</div></div> 14 MOA is crazy...I wonder what it would be on other rifles. I just got mine back today so I am going to take it to the range this coming weekend and see what it can do. I never do suppressed and unsuppressed POI as I never shoot unsuppressed so it doesn't matter to me what it is. But, that seems excessive.

 

[nfoley]

Re: Puzzling Suppressed Groups -

JStarz,
I'm anxious to hear about your results with your can now. Best of luck!

 

[JSTARSZ]

Re: Puzzling Suppressed Groups -

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: nfoley</div><div class="ubbcode-body">JStarz,
I'm anxious to hear about your results with your can now. Best of luck!</div></div> I am going to take my Thunderbeast 30P-1 and the HVT and use the same rifle and change cans for five round groups. I know the rifle I am shooting shoots 1/2 MOA groups with the Thunderbeast as I have done that numerous times. This should give me a decent understanding on what the two will do with a single rifle that I know is a shooter.

 

[JSTARSZ]

Re: Puzzling Suppressed Groups - Updated report 5/6/12

Ok, what are we looking at here? I finally got the HVT suppressor back from Gemtech and it is now without the QD mount and is a direct thread on. One thing that is different is that it is shorter and lighter because of the removal of the QD mount. This is the first opportunity to take the Thunderbeast 30P-1 and the Gemtech HVT out for some comparison.

This is in no way scientific; however, here are the particulars:
I used my GA Precision M40A3 and hand loaded Hornady 168GR AMAX which I know this rifle likes and saw some preliminary results. All groups were five rounds except the last that had six. I let the suppressors cool between strings except for group five that I took the Thunderbeast off and put on the HVT which was still very warm.

The Thunderbeast is definitely a Precision Rifle Suppressor as you can see by strings 1 and 4...I have shot the Thunderbeast on other Precision rifles and I always get the same results so that is my go to can. The Gemtech I have had some issues with in the past and was not very consistent. Strings 2, 3 and 5 were with the HVT. I still have lateral stringing with this can not as bad as before with the mount but it is still there.

Every string shows a distinct lateral movement - normally the first round is the furthest left and then it will move rightward as it warms up. The last groups, six rounds, was completed with little cooling and the first round was the furthest left and then the next five were grouped pretty well. That has always been the case with this suppressor, when it warms up it groups better but as far as first round hits at distance, I would have to work a lot more with it to see if I can figure out how to dial the first round.

the GA Precision M40A3 sporting the Gemtech HVT

My next test will be using the HVT with a Noveske 6.8mm 10.5" SBR that I may use for hunting. we shall see if it does better with a shorter more rigid barrel.

 

[LtDan]

Re: Puzzling Suppressed Groups - Updated report 5/6/12

Excellent, thanks for taking the time to compare and photograph. My only hope is one day Thunderbeast will take trade ins on like new Gemtech HVT suppressors.