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Very Hot Topic (More than 25 Replies) Subsonic Schuetzen (Read 13994 times)
boats
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Re: Subsonic Schuetzen
Reply #15 - Jan 21st, 2008 at 10:05pm
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BFD

I like original thinkers too, but do not want to jeopardize match performance with theory. Someone could work up sub sonic loads for 32 caliber Schuetzen bullets and enter them in competition against the tried and true 1450 fps loads.

We would be able to tell in short order which theory is correct. To date unless some can show me otherwise, supersonic muzzle to target has been the best performer

Boats
  
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Brent
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Re: Subsonic Schuetzen
Reply #16 - Jan 21st, 2008 at 10:12pm
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boats, 
Have you seen anyone be consistently successful with supersonic .22s at 200 yds?   Have you tried supersonic .22s and how did they compare to subsonics?   

Any idea of why this should work for .22s and not .32s?

No one is asking you to shoot subsonics if it bothers you of course, but sometimes it is worth trying new things.

I think if I were into shooting smokeless centerfire, a .32-20 subsonic would be just the ticket.

Brent
  
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38_Cal
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Re: Subsonic Schuetzen
Reply #17 - Jan 21st, 2008 at 10:43pm
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If my admittedly fallible memory is correct, .22 long rifle high velocity ammo goes subsonic at the 80 to 95 yard area, depending on initial velocity, bullet shape, wind, air pressure and which pair of teeth you hold your tongue between when you fire the shot.  The transition to subsonic causes wobble, and it's not predictable what direction the bullet will be pointing when it settles out.  High velocity loads that shoot great at 50 yards won't reliably hold minute of (gallon) milk carton at 100...this from personal experience.  There may be individual exceptions, I haven't tried every brand/variation of ammo...

David
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David Kaiser
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KWK
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Re: Subsonic Schuetzen
Reply #18 - Jan 22nd, 2008 at 6:37am
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The above reports of past failures with subsonic rounds has me pondering the causes. 

The existing twist rate calculators (for spitzers only) indicate the needed twist rate is higher for subsonic speeds. If one has throttled back a traditional schuetzen cartridge such as the .32-40, the twist rate may be inadequate for subsonic work, especially for speeds approaching sonic. Further, one would be running reduced loads, possibly causing greater variations in speed. (For subsonic work, pistol length cases would be a better choice.)

I wonder if the disturbance at the muzzle of the ejected high pressure gases is less orderly with subsonic than with sonic rounds?

One problem with subsonic work would be getting ideal bullets. One wants the highest BC, which would be a high SD bullet with a rounded nose and a boat tail, and I'm not aware of any such bullets. 

In looking at the more arcing trajectory subsonic requires, the trajectory calculators indicate the arc for a typical bullet would go from 9" at 1500 fps to 19" at 1000, which really isn't a dramatic difference. Speed variations seem a more likely culprit here.

It seems I'll simply have to have a special barrel made for my T/C rifle to test all this out...
  

Karl
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Cat_Whisperer
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Re: Subsonic Schuetzen
Reply #19 - Jan 22nd, 2008 at 6:55am
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Did not Dr. Mann write of the wobbling effect at the transition from super to sub-sonic as being resolved at some distance past and potentially accurate?

It certainly was a larger grouping at the transition area.

  

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MartiniBelgian
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Re: Subsonic Schuetzen
Reply #20 - Jan 22nd, 2008 at 7:33am
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Bullet design might indeed be an issue - subsonic bullets do require a different profile from supesonic bullets, a Metford-profile comes to mind...  Rounded tip about 45% of calibre, long tangent ogive (about 50% of bullet length).  Those things do help in cutting subsonic drag - but will make shot spotting quite a bit harder!
  
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J.D.Steele
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Re: Subsonic Schuetzen
Reply #21 - Jan 22nd, 2008 at 10:51am
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I humbly suggest that some if not much of the vertical dispersion might be due to varying muzzle velocities. I further humbly suggest that reduced loads of smokleless in large cases such as the 32-40 can make it extremely difficult to achieve small spreads in velocity when compared to full-pressure loads, especially at subsonic velocities. I further humbly suggest that smaller cases and more pressure with smokeless might yield smaller vertical subsonic groups via smaller MV spreads, and that possibly black powder with compression and other BPCRS tactics might also yield less vertical dispersion. Might be worth a thought, or even a try.
Good luck, Joe
  
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KWK
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Re: Subsonic Schuetzen
Reply #22 - Jan 22nd, 2008 at 12:11pm
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Joe, that's the sort of cartridge I was thinking of. By using a medium to high pressure, one could ensure complete combustion of a charge of the fast pistol or shotgun powders. In principle that should help ensure more uniform speeds. The downside is that the charges will be small (unless you're working with big bores), and this may cause speed variations due to errors in throwing or weighing charges.

It's an interesting optimization problem. 

It seems experiment is required. I'll have to acquire two barrels for my T/C. One for the classic .32-40 and one for .32 H&R (pistol) or similar. All this yet I'm a lousy off-hand shot. Much work to be done, and I'm stuck overseas until summer.
  

Karl
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Re: Subsonic Schuetzen
Reply #23 - Jan 24th, 2008 at 8:42pm
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Quote:
I humbly suggest that some if not much of the vertical dispersion might be due to varying muzzle velocities. I further humbly suggest that reduced loads of smokleless in large cases such as the 32-40 can make it extremely difficult to achieve small spreads in velocity when compared to full-pressure loads, especially at subsonic velocities. I further humbly suggest that smaller cases and more pressure with smokeless might yield smaller vertical subsonic groups via smaller MV spreads, and that possibly black powder with compression and other BPCRS tactics might also yield less vertical dispersion. Might be worth a thought, or even a try.
Good luck, Joe



I humbly agree. Low load density in a barrier to success due to velocity variations, while the exterior ballistics issues are not significantly differentiated.  Mentioned earlier, the matter of required twist rate in different velocity regimes, I don't believe sub-sonic necessarily requires quicker twists.
  
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Re: Subsonic Schuetzen
Reply #24 - Jan 25th, 2008 at 8:03pm
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(You need to Login or Register to view media files and links) also estimates the twist needed, at Mach numbers from well subsonic to over Mach 3. It indicates subsonic twist rates are higher. I don't know how solid the theory underlying these calculations are, though.

I'm pretty sure fps variations are the problem with subsonic. The higher trajectory implies higher vertical descent rates when the target is reached. A given % error in fps probably translates into a given % (or % squared) shortfall in range, and with the higher descent rate, this implies greater vertical dispersion on target. In other words, the slower you go, the less the % spread in fps you're allowed. This compounds on the fact that at subsonic a given % spread is a smaller fps (absolute) spread to begin with.

Regarding a comment above on the typical Schuetzen speed possibly being the worst possible, I think it is. Drift calculators, such as at JBM's site, indicate drift is less for Mach 2 and above, than it is for subsonic. It seems the near supersonic of Schuetzen has the worst drift problem. With BP, Mach 2 isn't an option, and the fps variation problem gives subsonic apparently greater problems.
  

Karl
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leadball
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Re: Subsonic Schuetzen
Reply #25 - Jan 25th, 2008 at 9:20pm
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KWK;
        I think your calculations & theory are about right--I did my experimenting with a small case capacity 30/30 Wesson and tried to load every case the same --also tried bullets from 125 to 200 gr.  Not only have I decided that subsonic won't work for me but,  most good BR shooters today are shooting at a higher velocity that ever before, there is not much to be gained in winddrift by shooting 1500fps as opposed to 1300fps but at 1480-1500 you can stay supersonic at the 200yd target.     leadball
  
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Re: Subsonic Schuetzen
Reply #26 - Jan 26th, 2008 at 6:09am
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leadball, my little mental foray into the world of Schuetzen seems to have come to the same conclusion that BP target shooters in the 1800s did, namely that 1500 fps or so is about as good as it gets (with BP).

You mentioned the BR shooters striving for higher velocity. It was a question I put on a BR forum that led me to the information that wind drift declines at higher Mach numbers. The typical Schuetzen fps is worst for wind drift, but the advantage in tolerance to fps changes seems to fully compensate for this (when compared to subsonic).

Were jacketed bullets allowed in Schuetzen, the game would quickly home in on the solutions BR shooters now use, namely long pointy boat-tailed bullets at high speeds. There'd be no point in calling it Schuetzen any more, and there'd be no comparing modern scores to the old ones.

One might argue jacketed bullets should be acceptable if the fps is limited to traditional Schuetzen fps, and there might be advantages in accuracy to be gained from this. In looking at a few sites for custom bullets makers for BR, it seems even jacketed boat-tails can have problems with erosion on the boattail as the bullet peeks out of the muzzle, with this in turn affecting accuracy. Erosion may explain why lead boat-tail bullets aren't made (or at least not common). Long pointy boat-tail bullets would reduce wind drift even at Schuetzen speeds, and I must wonder if the "rebated" boat-tails some BR shooters are using would be feasible in lead bullets for Schuetzen. Wads might be a problem, though.

So, it seems I've convinced myself that the solution found in the 1800s--flat base bullets at 1500 fps--was the best possible for the technology of the day, which was BP and lead. The only way forward at BP velocities might be paper-patched, hard metal bullets. These were played with in the 1800s, but I don't think the theory of the day pointed them to the streamlined shapes we know of now. If you could get the jacket to shed neatly and get the wad to deal with the small bullet base, there might be some improvements to be had in drift dispersion in Schuetzen. A quick test would be to try the all-copper moly coated bullets from GS Custom. If the accuracy warranted it, plain sided versions for paper patching could then be made and tried.

Thanks for all the comments everyone,
Karl
« Last Edit: Jan 26th, 2008 at 6:17am by KWK »  

Karl
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leadball
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Re: Subsonic Schuetzen
Reply #27 - Jan 26th, 2008 at 9:21am
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KWK;
          The  charts I look at tell me that there's not much to be gained in windrift until the bullet gets well above 2000fps,so with a plain-base bullet [rules] we are pretty well stuck with about 1500fps. Do you agree.    leadball
  
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Re: Subsonic Schuetzen
Reply #28 - Jan 26th, 2008 at 2:31pm
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That's how I see it as well, leadball; one needs to get up around Mach 2 to start seeing reductions in drift. That could only be done with smokeless and paper patching. 

Being ignorant of the rules, I wasn't aware a flat base was a requirement; it was mentioned above that lead construction is required. I assume paper patching permitted, but I doubt it will improve things much. 

When my work load drops some, I'll write out a computer program to solve the math and let me verify that fps sensitivity is what has caused the woes with subsonic; I'm pretty sure this is the problem.
  

Karl
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Re: Subsonic Schuetzen
Reply #29 - Jan 26th, 2008 at 2:59pm
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KWK, if I read the rules correctly (and I HAVE read them a time or two) the bullet restrictions are for plain base lead with paper patching or "naked" with lube both being OK.  The SHAPE of the base is not specified, only that it can't have a gas check or any part of a metallic jacket.  You can use stepped base, base band or hollow base bullets, and many folks have shot GC bullets without the metallic gas checks, so if you want to go to the trouble of casting a boat tail bullet for instance, that would be legal, but I don't think you could drive plain lead alloy fast enough to gain a benefit from that shape.  JMHO, 'cause I've never tried it. I don't know of any factory moulds being made in that configuration, though.

Froggie
  
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