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Old April 18, 2018, 04:06 PM   #26
tobnpr
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POI will most always change with the addition of any muzzle device.
Ideally, the change in harmonics is consistent- and therefore known and not an issue as it is anticipated and compensated for. Anyone with a suppressed rifle knows the POI shift and simply dials the difference depending on whether the device is on, or off, the rifle. "Accuracy" should remain the same.

Barrel contact that's inconsistent, such as lying it over sticks, or barrel-mounted bipods (cringe-worthy) will not produce consistent changes to harmonics and will cause not only a POI shift- but often a degradation in accuracy as well.
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Old April 19, 2018, 08:36 AM   #27
agtman
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The simplest way for M1 Garand owners to test the 'harmonic' effect of attaching a bayonet - and thus accuracy and group dispersion on POI - is to shoot one 8-rd clip without the bayo attached, and then a second 8-rd clip with it mounted.

At, say, 100-yds, even with a tight bayo-on-barrel lock-up, you'll see a different POI and some amount of dispersion.

Now the real question is: how much does this change matter? Holding tight MOA groups on paper targets at 600-yds is one thing.

Inside 200-yd, in combat conditions, firing on enemy soldiers charging you (think: Chosin Reservoir), the effect of the bayo on "combat accuracy" is probably meaningless, ... and yet a mounted bayo gave the soldier an immediate secondary weapon to stay in the fight, once that en bloc clip went PING!

Last edited by agtman; April 19, 2018 at 04:20 PM.
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Old April 19, 2018, 09:38 AM   #28
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I agree with several others, the bayonet, if contacting the barrel, is affecting the harmonics of the barrel. This is the same reason "free floating" a barrel is the fastest way to accurize (debatable) your AR-15.

Quote:
Harmonics: The act of firing a gun generates a rapid pressure increase within the barrel bore, causing the barrel to resonate and vibrate in a whip-like fashion. The resultant harmonic oscillations of the barrel affect the terminal phase of the projectile's internal ballistics and in turn the initial status of its external ballistics, and therefore need to be minimized or tuned to limit their effects on accuracy. Generally the harmonic effects are proportional to the square of the barrel length, and so are generally only of concern in long guns such as rifles but not handguns. Some external accessories, called tuners or de-resonators, can also be mounted onto the barrel to modify the harmonic wave pattern so that the node is shifted as near to the muzzle as possible. Airguns have significantly lower barrel pressure, and therefore are far less affected by barrel harmonics than firearms.
So think of that bayonet as a form of tuning the resonant frequency of that barrel. Pretty sure this is why, historically, bayonets were for charges and close-quarter-who-cares-what-the-MOA-shift-is-because-the-enemy-is-10-feet-away.
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Old April 19, 2018, 10:33 AM   #29
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Quote:
I seldom shot my AK with the bayonet but the POI didn’t change the few times I did.
How would you know? Most of the groups I have seen from AKs looked more like buckshot patterns than measurable groups ;p

Quote:
Even a sniper rifle in a suppressed configuration is a close range weapon system.
Really? You are saying a suppressed rifle is inaccurate/does not have a repeatable POI? I call BS. It may have a different POI with the can on as opposed to with it off, but it most certainly can be sighted in with the can on and be used that way at range.

Quote:
You cannot suppress supersonic ammo.
The supersonic crack of the bullet is still there, true enough, but the suppressor does reduce the sound and muzzle blast of the rifle. A reduced firing signature is a good thing, if you don't want to be seen and thus targeted.
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Old April 19, 2018, 04:18 PM   #30
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We're off-topic here, but suppressors are commonly used on more current SWS's and will likely be expanded to be standard kit for many more.

Disadvantages; frequent disassembly/cleaning, length added to the weapon making handling more difficult, and added weight. The advantages of sound suppression, flash suppression (perhaps even more important than sound) and enhanced communication between the sniper and his spotter make having it available, a no-brainer. The Operator will determine whether or not it would be advantageous to deploy depending on the nature of the engagement-but saying a suppressed SWS is a "close range weapon system" seems to be devoid of any factual basis.

Recent article on use of suppressors on the battlefield from the Military Times:

https://www.militarytimes.com/news/y...field-tactics/
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Old April 22, 2018, 09:48 AM   #31
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Quote:
saying a suppressed SWS is a "close range weapon system" seems to be devoid of any factual basis.
Really??

Huh, you should write the SOTIC committee and let them know!

Do not confuse employment with capability. Audie Murphy discovered that 60 mm mortar rounds had the capability to be used as makeshift hand grenades. That has nothing to do with how the US Army employed 60 mm Mortar ammunition.

1. A suppressor is not a functioning suppressor without subsonic ammunition.

Little physics:

Lower velocity = lower energy = shorter range..

Does anything else need to be said or do we understand the physics and why your suppressed sniper rifle is a close range weapon with a suppressor as compared to its engagement distances unsuppressed?

2. Shooting a suppressor with supersonic ammunition turns it into nothing more than a very expensive flash hider. A nice flash hider but it is not a suppressor anymore. I agree the sonic crack can actually help in concealment but that is NOT how suppressors are employed in the US Army at the time I was trained and USED them.

3. Once more suppressors are pretty restricted in their life limits and a round count was required. As suppressor technology advances I agree that it would not be a bad thing and is becoming more practical to use.
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Old April 22, 2018, 09:59 AM   #32
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Once more, in terms of practical sniper field craft, a suppressor does little to reduce the number one thing that gets you busted in your shooting position. It is not the muzzle flash that gives you away. It is the dirt and leaves that gets kicked up by pressure wave of the round exiting the barrel.
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Old April 22, 2018, 10:46 AM   #33
Art Eatman
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I can hardly wait for the command, "Fix suppressors!"
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