Learned a lesson about poi shift and why

Road_Clam · February 11, 2018, 08:22 AM

Yesterday I hit the range with my FNX45T and my Rev45 can and did some shooting. I generally shoot at 50 ft and my 1st 10 shots were nice, shot about a 6" group at 50ft. and shot a little high and right (my typical shooter deficiency). had an unusual flier about 10" low and right. The next 10 shots were horrible, all shots sprayed around a 8" group, 10" off poi at 5 oclock ??? Low and behold my can came loose. I also observed i struck the end cap with a bullet. I was SO mad at myself. People warned about semi auto cans coming loose. The end cam strike was not bad, and all the internal cones are fine, but a $80 mistake to the tune of a new end cap. Problem is my Rev45 can has a funky piston that uses a strange proprietary wrench. You really can't use a traditional wrench to tighten the can to the barrel. I'll just have to use my glove and check for tightness after each mag.

Don Fischer · February 11, 2018, 11:21 AM

OK, what's a can?

Road_Clam · February 11, 2018, 02:02 PM

"can" = "suppressor"

Don Fischer · February 12, 2018, 11:17 AM

AH! I'd never heard one called that before.

Mobuck · February 13, 2018, 11:13 PM

Have you seen the Black Rifle Coffee "Christmas Carole" video.
"Ralphie in the pink rabbit suit" sends a can downrange during a long burst. Big OOps.

TrueBlue711 · February 23, 2018, 04:16 PM

Road Clam: Was your can direct thread to the barrel or on some sort of QD muzzle device?

Road_Clam · February 23, 2018, 05:35 PM

Quote:

Originally Posted by TrueBlue711

Was your can direct thread to the barrel or on some sort of QD muzzle device?

I have a direct mount. It's getting to be a frustrating issue with my combo. I have to check tightness after each mag. I may fabricate a special piston wrench so I can get some better torque rather than just hand tight.

Machineguntony · February 24, 2018, 01:39 AM

Often/sometimes POI shift is really the bullet grazing some part of the silencer, such as the end cap.

I had a Liberty silencer that would shift my MP5 about 5 inches at 25 yards. It looked nor,al from the outside, but I found out about the strikes when I took removed the end cap and saw an ever so flight deformation on the inside of the end cap.

I am not a fan of direct thread silencers. I hate having to check the silencer every few shots just to make sure it hasn’t unscrewed itself.

Road_Clam · February 24, 2018, 07:57 AM

Quote:

Originally Posted by Machineguntony

Often/sometimes POI shift is really the bullet grazing some part of the silencer, such as the end cap.

I had a Liberty silencer that would shift my MP5 about 5 inches at 25 yards. It looked nor,al from the outside, but I found out about the strikes when I took removed the end cap and saw an ever so flight deformation on the inside of the end cap.

I am not a fan of direct thread silencers. I hate having to check the silencer every few shots just to make sure it hasn’t unscrewed itself.

Do you have better retention with 3 lug mount systems ? Griffin offers a 3 lug conversion for my Revolution 45 :

https://www.griffinarmament.com/3-Lu...p/gar40qdk.htm

https://www.griffinarmament.com/45-C...s-p/3lug45.htm

Theohazard · February 24, 2018, 09:27 AM

3-lug adaptors get rid of the piston, so it would turn a tilting-barrel locked-breech pistol like your FNX into a single-shot.

One method I’ve used in the past for keeping my pistol cans tight on the threads is a single drop of loctite. Apply it in the middle of the barrel’s threads and let it dry overnight. Then when you thread the can on it will be tighter but it won’t stick too hard. Keep in mind that if you get the can hot enough it will melt the loctite and it will turn into a lubricant. It doesn’t take much shooting for this to happen with regular blue loctite, so you might try some that’s meant for higher temps.

Machineguntony · February 24, 2018, 10:12 AM

I’ve never seen a three lug on pistol. Usually a three lug is on something like an SMG or a carbine of some sort, where heavy fire is expected. As Theo said, the loctite solution is an imperfect solution. Too much and you’ll glue the can, too little and you just end up lubing the threads.

I do hate direct thread silencers, but for pistols, I’m not sure if there’s an alternative on the market. There might be, but I’m not aware of one. I’m also not sure that there can be a solution.

I imagine some sort of solution where there is a mount that just reverses the threading, so that the silencer doesn’t spin off. But then that would require manufacturing the silencer with a reverse threading, and if you lost the mount, you’d be screwed.

In the end, I think the problem that we are discussing doesn’t have a perfect solution bc the ‘problem’ isn’t part of the original design. Meaning, a pistol silencer wasn’t originally designed to be used with hundreds of rounds and magazines upon magazines of fire.

An analogy...

A while back I called Mike at TSC machine, who is super knowledgeable about MP5s, and I complained to him that my MP5SD wouldn’t last hundreds of rounds without losing efficacy. After a mere 200 rounds, it gets louder and with another 200 rounds, the thing gets possibly carbon locked. He warned me not to shoot it beyond a couple hundred rounds without cleaning.

So I was like, ‘what the hell, I have a gun I can only run with 200 rounds?’

I asked him how to fix it, and his response was that the SD is a commando gun, designed for a short mission, and it was never designed for range warriors to shoot 2000 rounds on a weekend range trip. It needs a cleaning every 200 or so rounds. That’s the downside of a factory spec SD.

Granted, the solution is to get an SD made by RDTS, which can go thousands of rounds, but those aren’t HK spec SDs, and the RDTS SDs can not be disassembled at home. So it’s not a perfect solution.

Bottom line is there is no complete solution because the thing was designed for something that isn’t compatible with our objective.

So in the end, we just need to keep checking the silencer to make sure it hasn’t unscrewed.

But I’m not a silencer expert.

Is there a perfect solution, Theo?

Theohazard · February 24, 2018, 11:44 AM

Not that I know of. Metric left-handed threads tend to allow the can to loosen less than right-handed threads. Many people claim this is due to the difference between the direction of the threads and the direction of the rifling twist on most pistols. Me, I think it probably has more to do with the difference in the thread design between the two types of thread specs. For example, the difference between the two 9mm standard threadings (13.5x1 left-hand metric and 1/2x28 right-hand) are more than just the thread direction. And these differences are also there between the thread specs for the other calibers. Someday when I have more time on my hands I'll do a detailed experiment to see if I'm right or not.

I've heard of people using Teflon tape on the threads to tighten things up. As long as the can is still allowed to shoulder properly this shouldn't hurt anything, but I've never tried it myself. Some people use lock washers, and this is a bad idea since it can misaligned the can. Me, I just make sure to tighten my can if it looks like it's coming loose. The key is to notice it's coming loose before it backs off the threads too far.

Once my Octane is screwed onto the barrel, I pull out on the can (compressing and unlocking the piston assembly) and rotate it until the big "SilencerCo" is on the left side (because I'm right handed). This means I can quickly see if my silencer is coming unscrewed during firing. You could also put a white mark on the back edge of the can to accomplish the same thing.

This is the main advantage in my opinion of an offset design like the Osprey. It's really easy to see if the can is coming unscrewed during firing.

Road_Clam · February 24, 2018, 05:16 PM

Thanks guys for the excellent feedback. I did reach out the Griffin tech support to see what they suggest. I'll report back.

MislMan · February 26, 2018, 04:38 PM

Anybody tried a star washer or a wave washer to add a little tension? Just check alignment with a wooden dowel from Home Depot.

Theohazard · February 26, 2018, 07:21 PM

A washer like that is likely to mis-align the can. And it might misalign it enough to cause baffle strikes. I highly recommend never using anything between the silencer and the shoulder that isn’t specifically designed for use with a silencer. But if you use one anyway, make extra sure to check alignment every single time you screw the can on, not just the first time. And I wouldn’t use a wooden dowel, those aren’t precise enough.

Road_Clam · February 27, 2018, 06:41 AM

Got a reply from Griffin, got a very short "it is what it is" type reply. Some suggested try wrapping the threads with Teflon tape. Might try that.

February 11, 2018, 08:22 AM	#1
Road_Clam Senior Member Join Date: November 21, 2013 Location: New Hampshire Posts: 1,695	Learned a lesson about poi shift and why Yesterday I hit the range with my FNX45T and my Rev45 can and did some shooting. I generally shoot at 50 ft and my 1st 10 shots were nice, shot about a 6" group at 50ft. and shot a little high and right (my typical shooter deficiency). had an unusual flier about 10" low and right. The next 10 shots were horrible, all shots sprayed around a 8" group, 10" off poi at 5 oclock ??? Low and behold my can came loose. I also observed i struck the end cap with a bullet. I was SO mad at myself. People warned about semi auto cans coming loose. The end cam strike was not bad, and all the internal cones are fine, but a $80 mistake to the tune of a new end cap. Problem is my Rev45 can has a funky piston that uses a strange proprietary wrench. You really can't use a traditional wrench to tighten the can to the barrel. I'll just have to use my glove and check for tightness after each mag. __________________ "To be old an wise you must have been young and stupid"

February 11, 2018, 02:02 PM	#3
Road_Clam Senior Member Join Date: November 21, 2013 Location: New Hampshire Posts: 1,695	"can" = "suppressor" __________________ "To be old an wise you must have been young and stupid"

February 24, 2018, 01:39 AM	#8
Machineguntony Senior Member Join Date: June 22, 2013 Posts: 1,277	Often/sometimes POI shift is really the bullet grazing some part of the silencer, such as the end cap. I had a Liberty silencer that would shift my MP5 about 5 inches at 25 yards. It looked nor,al from the outside, but I found out about the strikes when I took removed the end cap and saw an ever so flight deformation on the inside of the end cap. I am not a fan of direct thread silencers. I hate having to check the silencer every few shots just to make sure it hasn’t unscrewed itself. __________________ Sent from Motorola DynaTac 8000x

February 24, 2018, 09:27 AM	#10
Theohazard Senior Member Join Date: April 19, 2012 Location: Western PA Posts: 3,829	3-lug adaptors get rid of the piston, so it would turn a tilting-barrel locked-breech pistol like your FNX into a single-shot. One method I’ve used in the past for keeping my pistol cans tight on the threads is a single drop of loctite. Apply it in the middle of the barrel’s threads and let it dry overnight. Then when you thread the can on it will be tighter but it won’t stick too hard. Keep in mind that if you get the can hot enough it will melt the loctite and it will turn into a lubricant. It doesn’t take much shooting for this to happen with regular blue loctite, so you might try some that’s meant for higher temps. __________________ 0331: "Accuracy by volume." Last edited by Theohazard; February 24, 2018 at 09:32 AM.

February 24, 2018, 10:12 AM	#11
Machineguntony Senior Member Join Date: June 22, 2013 Posts: 1,277	I’ve never seen a three lug on pistol. Usually a three lug is on something like an SMG or a carbine of some sort, where heavy fire is expected. As Theo said, the loctite solution is an imperfect solution. Too much and you’ll glue the can, too little and you just end up lubing the threads. I do hate direct thread silencers, but for pistols, I’m not sure if there’s an alternative on the market. There might be, but I’m not aware of one. I’m also not sure that there can be a solution. I imagine some sort of solution where there is a mount that just reverses the threading, so that the silencer doesn’t spin off. But then that would require manufacturing the silencer with a reverse threading, and if you lost the mount, you’d be screwed. In the end, I think the problem that we are discussing doesn’t have a perfect solution bc the ‘problem’ isn’t part of the original design. Meaning, a pistol silencer wasn’t originally designed to be used with hundreds of rounds and magazines upon magazines of fire. An analogy... A while back I called Mike at TSC machine, who is super knowledgeable about MP5s, and I complained to him that my MP5SD wouldn’t last hundreds of rounds without losing efficacy. After a mere 200 rounds, it gets louder and with another 200 rounds, the thing gets possibly carbon locked. He warned me not to shoot it beyond a couple hundred rounds without cleaning. So I was like, ‘what the hell, I have a gun I can only run with 200 rounds?’ I asked him how to fix it, and his response was that the SD is a commando gun, designed for a short mission, and it was never designed for range warriors to shoot 2000 rounds on a weekend range trip. It needs a cleaning every 200 or so rounds. That’s the downside of a factory spec SD. Granted, the solution is to get an SD made by RDTS, which can go thousands of rounds, but those aren’t HK spec SDs, and the RDTS SDs can not be disassembled at home. So it’s not a perfect solution. Bottom line is there is no complete solution because the thing was designed for something that isn’t compatible with our objective. So in the end, we just need to keep checking the silencer to make sure it hasn’t unscrewed. But I’m not a silencer expert. Is there a perfect solution, Theo? __________________ Sent from Motorola DynaTac 8000x

February 11, 2018, 11:21 AM	#2
Don Fischer Senior Member Join Date: March 2, 2017 Posts: 1,868	OK, what's a can?

February 12, 2018, 11:17 AM	#4
Don Fischer Senior Member Join Date: March 2, 2017 Posts: 1,868	AH! I'd never heard one called that before.

February 13, 2018, 11:13 PM	#5
Mobuck Junior member Join Date: February 2, 2010 Posts: 6,846	Have you seen the Black Rifle Coffee "Christmas Carole" video. "Ralphie in the pink rabbit suit" sends a can downrange during a long burst. Big OOps.

February 23, 2018, 04:16 PM	#6
TrueBlue711 Senior Member Join Date: March 16, 2011 Posts: 489	Road Clam: Was your can direct thread to the barrel or on some sort of QD muzzle device?

February 24, 2018, 11:44 AM	#12
Theohazard Senior Member Join Date: April 19, 2012 Location: Western PA Posts: 3,829	Not that I know of. Metric left-handed threads tend to allow the can to loosen less than right-handed threads. Many people claim this is due to the difference between the direction of the threads and the direction of the rifling twist on most pistols. Me, I think it probably has more to do with the difference in the thread design between the two types of thread specs. For example, the difference between the two 9mm standard threadings (13.5x1 left-hand metric and 1/2x28 right-hand) are more than just the thread direction. And these differences are also there between the thread specs for the other calibers. Someday when I have more time on my hands I'll do a detailed experiment to see if I'm right or not. I've heard of people using Teflon tape on the threads to tighten things up. As long as the can is still allowed to shoulder properly this shouldn't hurt anything, but I've never tried it myself. Some people use lock washers, and this is a bad idea since it can misaligned the can. Me, I just make sure to tighten my can if it looks like it's coming loose. The key is to notice it's coming loose before it backs off the threads too far. Once my Octane is screwed onto the barrel, I pull out on the can (compressing and unlocking the piston assembly) and rotate it until the big "SilencerCo" is on the left side (because I'm right handed). This means I can quickly see if my silencer is coming unscrewed during firing. You could also put a white mark on the back edge of the can to accomplish the same thing. This is the main advantage in my opinion of an offset design like the Osprey. It's really easy to see if the can is coming unscrewed during firing. __________________ 0331: "Accuracy by volume." Last edited by Theohazard; February 24, 2018 at 11:51 AM.

February 24, 2018, 05:16 PM	#13
Road_Clam Senior Member Join Date: November 21, 2013 Location: New Hampshire Posts: 1,695	Thanks guys for the excellent feedback. I did reach out the Griffin tech support to see what they suggest. I'll report back. __________________ "To be old an wise you must have been young and stupid"

February 26, 2018, 04:38 PM	#14
MislMan Member Join Date: July 20, 2015 Posts: 57	Anybody tried a star washer or a wave washer to add a little tension? Just check alignment with a wooden dowel from Home Depot.

February 26, 2018, 07:21 PM	#15
Theohazard Senior Member Join Date: April 19, 2012 Location: Western PA Posts: 3,829	A washer like that is likely to mis-align the can. And it might misalign it enough to cause baffle strikes. I highly recommend never using anything between the silencer and the shoulder that isn’t specifically designed for use with a silencer. But if you use one anyway, make extra sure to check alignment every single time you screw the can on, not just the first time. And I wouldn’t use a wooden dowel, those aren’t precise enough. __________________ 0331: "Accuracy by volume."

February 27, 2018, 06:41 AM	#16
Road_Clam Senior Member Join Date: November 21, 2013 Location: New Hampshire Posts: 1,695	Got a reply from Griffin, got a very short "it is what it is" type reply. Some suggested try wrapping the threads with Teflon tape. Might try that. __________________ "To be old an wise you must have been young and stupid"

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