Can Anyone Guess..

[Treetop]

What velocity I'm getting with this load and revolver?

The Load- Lyman 452460 200 gr. SWC, .452 dia. WQWW, in front of 9.0 gr. Unique, standard LP primer, Remington .45 Colt brass.

The revolver- S&W Model 25-2 with a custom .45 Colt cylinder. 6 1/2 inch barrel.

My chronograph finally died on me after almost 25 years of service. The load is very pleasant to shoot with good accuracy and no leading. I'm guessing the velocity is around 900-925 fps. Deer season starts down here in Texas this coming Saturday, so I'm thinking this will be my 25 yard and under whitetail and hog load.

I carefully lined up seven 1 gallon milk jugs, full of water, to check penetration and see what my bullet looked like. The bullet tore the first two jugs up, soaked me, and exited the seventh jug, impacting the berm down range! I had no idea that a "light weight" 200 gr. boolit would have that much penetration! Yeah, I know, they are milk jugs, not deer, but still...

[MtGun44]

I think you may be getting a bit more velocity. The I get around 1050 with a 250-260
Keith in my .44 mags over 10 gr Unique. So - lighter boolit, larger diam, just a tad less
powder - my bet is about 1000 even.

Bill

[S.R.Custom]

What's your barrel/cylinder gap? Has a huge impact on velocity.

[9.3X62AL]

Been there/done that with a BisHawk x 7.5", and it yielded right around 1000 FPS. Nice load, and would do for our coyote-sized deer and deer-sized coyotes. The revolver does better work with #454424 and #454190 (group size/longer ranges), but at 25 yards I would use it.

[beagle]

Well, I'm getting 941 FPS with a 454190 and 9.2 grains of Unique out of a 454190 249 grain bullet out of a 5 1/2" Blackhawk so I'm guessing you're way past 1,000 FPS with that lighter bullet./beagle

[littlejack]

I'm betting you're getting close to 1100 fps.
Jack

[Treetop]

What's your barrel/cylinder gap? Has a huge impact on velocity.

Thanks SuperMag,

I forgot to include that. My barrel/cylinder gap is .0025".

[Treetop]

Thanks for the replies everyone. Any recommendations on a new chronograph? Mine was old and outdated, but it had a 5 foot screen spacing which was supposed to increase the accuracy. All I can find now are 2 or 3 foot spaced screens.

Any help would be appreciated because I'm uncomfortable without my chronograph. Kinda like going to work in the morning and forgetting your watch-you just don't feel "right" all day:-D.

[DevilDog83]

I've had great luck with the "ProChrono" Digital. Bought it from Midway for around $100.00. If you have an indoor range, I'd suggest getting the light attachment kit. Semper Fi Treetop

[Bucks Owin]

Thanks for the replies everyone. Any recommendations on a new chronograph? Mine was old and outdated, but it had a 5 foot screen spacing which was supposed to increase the accuracy. All I can find now are 2 or 3 foot spaced screens.

Any help would be appreciated because I'm uncomfortable without my chronograph. Kinda like going to work in the morning and forgetting your watch-you just don't feel "right" all day:-D. I've been using a $69 Shooting Chrony for about 4 or 5 years. I set it up 3 ft from the muzzle on a tripod. It's face is splattered with bullet lube and it's pockmarked with powder grains until it's hard to read sometimes. After thousands of close up muzzle blasts, it's still working fine. In fact I'm thinking of splurging for the ballistic printer for it! Fits perfectly in a .30 cal ammo can. They're built "Ford tough" :lol:.....FWIW, Dennis (Who will buy another IF this one ever dies!) PS: My 7.5" Blackhawk required 9.2 grs of Unique to reach 1000 fps with a 200 gr boolit FWIW...

[MtGun44]

Screen spacing is related to the number of pulses per second that the chrono is
using. If the pulse rate is slow you will only get a few pulses in a short distance to
being off a pulse or two can be more error than you want. Modern chronos run at
higher frequencies than older ones, so get the same accy with shorter screen spacing.

Example. Suppose you are shooting a very high velocity cartridge at 4000 ft/sec.

With 5 ft screen spacing the time is .00125 seconds. If the chrono is running at a
clock rate of 5000 cycles per second, there will be only 6.25 pulses between start
and stop, so the chono (which can only count full pulses) will show 6 cycles, an error
of 4%. If there is a full pulse error, then you have an error of 16.66% -- pretty bad.

If you go to 10 ft spacing, you will get twice the number of pulses, half the error
with a single pulse miscount. OR you could run the chrono at 20,000 pulses per
second and cut the distance to 2 ft. Then you get .0005 sec, but this is 10 pulses
so a single pulse error is 10%. So, I imagine that for a 2 ft screen spacing you want
100,000 cycles per second to get 50 pulses which cuts the single pulse error down to
2%. Higher frequency circuits used to be harder to make and control to very high
frequency accuracy. Phase locked loop circuits makes that easier and cheaper with
today's chips. Circuits drift in frequency with temperature and age of components, so
with feedback loop circuits you can correct for this. Ain't modern electronics wonderful!

Bill

[Treetop]

Modern chronos run at
higher frequencies than older ones, so get the same accy with shorter screen spacing.
Bill

Thanks for the information, MtGun44. I wondered why no one offered the five foot screen spacing anymore. Now I will feel comfortable with a "modern" 2 or 3 foot spacing.