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Confused...supersonic loads impacting lower than subsonic? Login/Join 
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I was shooting a handful of 22s today, 3 10/22, 3 cz 455. Was shooting 7 different loads. Ranging from 910fps up to 1250.

On the 4th rifle(CZ 455 American, unsuppressed) I went through through the first 4 loads(CCI SV, CCI SUPPRESSED, ELEY CLUB AND ELEY TARGET) , all were within reason of how they performed in the other rifles. This rifle was zeroed with CCI SV. When I got to the first group of Supersonic ammo, it shot about 4in low. I tried 2 more supersonic loads....one 3in low, the other about 4in as well.


Distance was 50yd. How are supersonics shooting lower than the subsonic?


I get different ammo will varying POI compared to the ammo it was sighted with. What I can't understand is how a bullet traveling 100-250 fps faster, impacts 3-4in lower. None of the other rifles I fired exhibited this. As expected they were similar or slightly higher.

Thoughts?


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Posts: 7708 | Location: One step ahead of you | Registered: February 10, 2009Reply With QuoteReport This Post
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What are the projectile weights and profiles?

CZ452's (not sure about 455's) in .22LR are known to have very tight bores and many people advise using a .17 cleaning rod with a thread adapter to attach a .22 brush. That is a difference compared to the 10/22 but I'm still thinking about why you saw what you did.
 
Posts: 2245 | Location: Indiana | Registered: December 28, 2004Reply With QuoteReport This Post
Lost
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How are supersonics shooting lower than the subsonic?

Physics. Specifically dwell time in the barrel. Think what the barrel does as soon as the round is set off. It begins recoiling up, raising the eventual POI.

A subsonic round by definition stays in the barrel longer, so that at the moment the bullet leaves the muzzle, the barrel is pointing relatively high. So the round prints high on the target.

A supersonic round leaves the barrel quicker, before it has a chance to tilt the barrel higher. It prints low.

(There is a point [i.e. range] where the slower projectile would once again hit lower, even compensating for the higher aspect angle of the barrel. That all would depend on specifics such as velocity, bullet weight, ballistic coefficient. etc.)

It also depends on the specific rifle you're using. Does your CZ have a longer barrel? Is the overall weight signicantly lighter than the other rifles?



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Posts: 13726 | Location: SF Bay Area | Registered: December 11, 2003Reply With QuoteReport This Post
fugitive from reality
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Welcome to the wonderful world of the 22lr barrel harmonics. Like kkina said, the HV stuff is leaving your barrel at a different point in the barrel whip than the subsonic stuff is.


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Posts: 6720 | Location: Newyorkistan | Registered: March 28, 2007Reply With QuoteReport This Post
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I've been handloading for about 20 years and understand abrrwl harmonics and its affect on point of impact, i just done ever recall seeing anything like this.

I suppose I didn't think a lighter bullet, 36gr, traveling 200fps faster would impact lower, let alone 4in. @50 yards. What you're saying is that the trajectory of the supers is that much flatter then the sunsonic they have havent risen as quickly? That makes total sense. I jsit didn't expect it with 200fps difference. None of the other guns expereinced this, they were all about 1in high.

The barrel is 20.5in. Weight wise,its in the middle-of-the-road the other rifles, but this one has a pencil barrel.The other guns had 16in and 18in barrels. I do have 24in 455 that I may try today. A buddy of mine who was there had a CZ 452 and he did not experience the same.
Perhaps its just this particular gun. Not a big deal, jsut havent encountered that before.


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Posts: 7708 | Location: One step ahead of you | Registered: February 10, 2009Reply With QuoteReport This Post
Freethinker
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Dwell time in the barrel I might accept, but barrel whip with any normal 22 Long Rifle gun?
That seems … counterintuitive to say the least. Are there external sources of information anyone can point to that demonstrate that phenomenon?




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Posts: 42581 | Location: 10,150 Feet Above Sea Level in Colorado | Registered: April 04, 2002Reply With QuoteReport This Post
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quote:
Originally posted by WARPIG602:
I suppose I didn't think a lighter bullet, 36gr, traveling 200fps faster would impact lower, let alone 4in. @50 yards. What you're saying is that the trajectory of the supers is that much flatter then the sunsonic they have havent risen as quickly? That makes total sense. I jsit didn't expect it with 200fps difference. None of the other guns expereinced this, they were all about 1in high.

I have three 22lr rifles -- lever action, AR15 upper, and precision bolt action. All three rifles are zeroed at 50 yards with subsonic ammo -- middle of the road stuff (CCI Standard) for the lever action, and true match-grade ammo for the other two. At 50 yards, the supersonic ammo I have used all impact higher than subsonic zero -- generally by 1/2" to 3/4". I have never seen supersonic ammo impact lower than subsonic ammo at 50 yards. Even 100 yards.

If you're seeing impacts 4" low with supersonic at 50 yards, there's something wonky going on.
 
Posts: 6655 | Location: Colorado | Registered: January 26, 2008Reply With QuoteReport This Post
fugitive from reality
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OP said he tried three different supersonic 22lr loads, and they all shot between 3" and 4" low. Whatever is happening, it's happening with higher velocity ammo. That tells me that with more energy there is more vibration, and that vibration is causing the groups to shoot low. Barrel whip might have been the wrong phrase to use, but the end result is the same.

quote:
Originally posted by fritz:
If you're seeing impacts 4" low with supersonic at 50 yards, there's something wonky going on.


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Posts: 6720 | Location: Newyorkistan | Registered: March 28, 2007Reply With QuoteReport This Post
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quote:
Originally posted by SgtGold:
OP said he tried three different supersonic 22lr loads, and they all shot between 3" and 4" low. Whatever is happening, it's happening with higher velocity ammo. That tells me that with more energy there is more vibration, and that vibration is causing the groups to shoot low. Barrel whip might have been the wrong phrase to use, but the end result is the same.

quote:
Originally posted by fritz:
If you're seeing impacts 4" low with supersonic at 50 yards, there's something wonky going on.


I have a 300WSM with a pencil barrel that I suspect would be more susceptible to barrel whip and or barrel hamronics, I havent seen the POI shift nearly off as this.

Not saying you're wrong, just something I havent encountered in shooting a lot of rifles and calibers.


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Posts: 7708 | Location: One step ahead of you | Registered: February 10, 2009Reply With QuoteReport This Post
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Reshot today. Yesterday we had 10-20mph winds. Today was better.

Same problem though.

Ignore the flyers in the CCI SV box, those were from yesterday.



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Yeah, that M14 video guy...
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I see it in M14's too. Higher velocity ammunition hits lower than lower velocity. Usually by about two inches.

Tony.


Owner, TonyBen, LLC, Type-01 FFL
www.tonybenm14.com (Site under construction).
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Posts: 4018 | Location: USA | Registered: February 13, 2001Reply With QuoteReport This Post
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quote:
Originally posted by benny6:
I see it in M14's too. Higher velocity ammunition hits lower than lower velocity. Usually by about two inches.

Tony.


Can the trajectory really be that different, at 50 yards? Im assuming thats what it has to be right?
Whats odd to me is that none of the other rifles had this issue.....so that rules out the trajectory theory?

Maybe i'll run back out with some Stingers and see what happens


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The barrel is 20.5in. Weight wise,its in the middle-of-the-road the other rifles, but this one has a pencil barrel.The other guns had 16in and 18in barrels. I do have 24in 455 that I may try today.

Ah ha, that makes sense. The CZ has a long, thin barrel. Longer dwell time, less mass to rotate up. I would also have expected the 24-inch barrel to exhibit the same phenomenon, perhaps even be more pronounced (unless it's a bull barrel).

I would hesitate to call this a barrel whip effect, since that would actually compensate for the barrel rise. Shooting rimfire, I would guess that the barrel stays relatively rigid during its rise cycle.

I also don't think I'd call this a trajectory issue either. It's just that the gun is shooting higher or lower depending on where the muzzle is pointing when the bullet leaves.



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Posts: 13726 | Location: SF Bay Area | Registered: December 11, 2003Reply With QuoteReport This Post
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quote:
Originally posted by kkina:
quote:
The barrel is 20.5in. Weight wise,its in the middle-of-the-road the other rifles, but this one has a pencil barrel.The other guns had 16in and 18in barrels. I do have 24in 455 that I may try today.

Ah ha, that makes sense. The CZ has a long, thin barrel. Longer dwell time, less mass to rotate up. I would also have expected the 24-inch barrel to exhibit the same phenomenon, perhaps even be more pronounced (unless it's a bull barrel).

I would hesitate to call this a barrel whip effect, since that would actually compensate for the barrel rise. Shooting rimfire, I would guess that the barrel stays relatively rigid during its rise cycle.

I also don't think I'd call this a trajectory issue either. It's just that the gun is shooting higher or lower depending on where the muzzle is pointing when the bullet leaves.


I just don't see the muzzle rising up with 22lr. Especially with subsonic. Certainly not enough to create a 3-4in rise.


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Posts: 7708 | Location: One step ahead of you | Registered: February 10, 2009Reply With QuoteReport This Post
Lost
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I just don't see the muzzle rising up with 22lr. Especially with subsonic. Certainly not enough to create a 3-4in rise.

By my calc, the muzzle rise to push POI up 3 inches at 50 yards is only about 1/16". You might not be able to see this movement unless recording in slow-motion. Seems entirely reasonable.



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Posts: 13726 | Location: SF Bay Area | Registered: December 11, 2003Reply With QuoteReport This Post
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Well I certainly don't have the equipment to argue, but, I dont see how a 40gr bullet traveling at 1070fps would case the barrel to rise at all.


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Posts: 7708 | Location: One step ahead of you | Registered: February 10, 2009Reply With QuoteReport This Post
Lost
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I found this on YT. Looking closely, you can tell that the muzzle is rising and falling almost imperceptably on most of the shots. And that's with muzzle weight on the end.




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Posts: 13726 | Location: SF Bay Area | Registered: December 11, 2003Reply With QuoteReport This Post
Yeah, that M14 video guy...
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I believe in the case of the M14, it has to do with the time it takes the bullet to leave the barrel versus the amount of muzzle rise (dwell time). The slower it is, the more the muzzle rises before the bullet exits, resulting in a higher POI.

There's also a gas cylinder, gas piston and operating rod that are attached to the barrel which may have something to do with the extreme shift in POI between different velocity ammo.

Tony.


Owner, TonyBen, LLC, Type-01 FFL
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Posts: 4018 | Location: USA | Registered: February 13, 2001Reply With QuoteReport This Post
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Hmm, im wondering if the movement is simply recoil or perhaps the mass of the action causing it to raise. Oddly enough I didn't encounter this with any of the 10/22 I shot. Just the bolt action with no rearward moment.


At this point, it's probably the only real possibility.


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fugitive from reality
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From a standpoint of physics if a fly lands on the end of a steel rod, the rod must bend. The fact that the human eye can't see it doesn't mean it's not true.

This message has been edited. Last edited by: SgtGold,


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