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FPS without Chrono
#6477063
10/02/16 05:12 PM
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Joined: Jun 2008
Posts: 7,939
bigjoe8565
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Is there a way to get close on FPS without the aid of a Chrono?
Shooting 165 grain SST over 44 grains of Varget out of an 18 inch 308 bolt gun.
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Re: FPS without Chrono
[Re: bigjoe8565]
#6477073
10/02/16 05:23 PM
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Joined: Nov 2007
Posts: 9,523
RiverRider
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Yes, you can get close by shooting at various ranges and using trajectory...BUT, it involves the BC of your bullet also and sometimes published BCs just don't match up to the real world. Another complication can result from the quality of stabilization. There is an ideal BC that may be published for any bullet but it assumes perfect stabilization. On each individual real-world shot, though, there will be an actual achieved BC. It can all be pretty complicated because there are variables you can't nail down.
"Arguing with you always makes me thirsty." -Augustus McRae
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Re: FPS without Chrono
[Re: bigjoe8565]
#6477087
10/02/16 05:32 PM
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Joined: Sep 2004
Posts: 141
parkj5
Woodsman
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Woodsman
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A chrono is a must for any reloader.. Best way to find pressure.. and test temp sensitive powders also.
parkj5
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Re: FPS without Chrono
[Re: parkj5]
#6477160
10/02/16 06:30 PM
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Joined: Sep 2016
Posts: 1,088
Creedmoor
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A chrono is a must for any reloader.. Best way to find pressure.. and test temp sensitive powders also. Just to add, it's only ONE thing in interpreting pressures. Your eyes can tell you more than any chronograph ever will when it comes to pressure signs. It's a good tool, but depending on it to show pressure signs is a recipe for disaster.
. There's a fine line between BRAVE ... and STUPID.
The two most important days in your life are the day you are born and the day you find out why.
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Re: FPS without Chrono
[Re: bigjoe8565]
#6477229
10/02/16 07:51 PM
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Joined: Dec 2008
Posts: 4,511
syncerus
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That said, high velocity is a great and unerring indicator of pressure where there are no visible signs.
NRA Patriot Benefactor & DSC Lifer
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Re: FPS without Chrono
[Re: Creedmoor]
#6477285
10/02/16 08:42 PM
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Joined: Jun 2015
Posts: 5,923
Jgraider
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A chrono is a must for any reloader.. Best way to find pressure.. and test temp sensitive powders also. Just to add, it's only ONE thing in interpreting pressures. Your eyes can tell you more than any chronograph ever will when it comes to pressure signs. It's a good tool, but depending on it to show pressure signs is a recipe for disaster. And vice versa as well. You can reach pressure way before you see any of the typical 'signs". Velocity is all about pressure.
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Re: FPS without Chrono
[Re: bigjoe8565]
#6477294
10/02/16 08:53 PM
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Joined: Nov 2007
Posts: 9,523
RiverRider
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"Arguing with you always makes me thirsty." -Augustus McRae
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Re: FPS without Chrono
[Re: bigjoe8565]
#6477326
10/02/16 09:12 PM
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Joined: Jun 2011
Posts: 33,988
Buzzsaw
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if your pressure signs are good and accuracy is good, you really don't need a chrono, went many, many years killing deer without one.
if you are using your load for 500 yard and out, you might, but with a hunting load as stated above, no chrono needed
SPACE FOR RENT
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Re: FPS without Chrono
[Re: bigjoe8565]
#6477390
10/02/16 09:46 PM
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Joined: Sep 2016
Posts: 1,088
Creedmoor
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[ You can reach pressure way before you see any of the typical 'signs". Velocity is all about pressure. So you guys are saying that if you work up a load (with appropriate powders for the caliber) without a chronograph you can blow up a gun before you see any pressure signs? No flattened primers, sticky bolt lifts, or other signs? Is that what you are saying?
. There's a fine line between BRAVE ... and STUPID.
The two most important days in your life are the day you are born and the day you find out why.
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Re: FPS without Chrono
[Re: bigjoe8565]
#6477442
10/02/16 10:30 PM
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Joined: Nov 2007
Posts: 9,523
RiverRider
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No, not at all. A gun doesnt blow up because you're two or three thousand psi over pressure. But, you can easily reach 70000 psi or more before pressure signs appear.
"Arguing with you always makes me thirsty." -Augustus McRae
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Re: FPS without Chrono
[Re: bigjoe8565]
#6477444
10/02/16 10:33 PM
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Joined: Nov 2007
Posts: 9,523
RiverRider
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Velocity is just another indicator, like the other well known pressure signs are...but it's a very good indicator, even if it's not 100% reliable---and it is NOT.
"Arguing with you always makes me thirsty." -Augustus McRae
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Re: FPS without Chrono
[Re: bigjoe8565]
#6477458
10/02/16 10:44 PM
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Joined: Aug 2009
Posts: 3,124
postoak
Veteran Tracker
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Oh, someone put the Powley Computer online. Powley Computer
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Re: FPS without Chrono
[Re: bigjoe8565]
#6477565
10/02/16 11:53 PM
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Joined: Jun 2008
Posts: 7,939
bigjoe8565
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I have no pressure signs at 44 or even 44.5, but at 45 the bolt got a little stiff to open. My accuracy node is 44 grains of Varget .75" on average, but at 44.5 my accuracy is 1-1.1"on average.
I was looking for FPS to run the data through a ballistic calculator. Guess I'll buy a chrono. Any recommendations on a reliable chrono that won't break the bank?
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Re: FPS without Chrono
[Re: bigjoe8565]
#6477581
10/03/16 12:04 AM
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Joined: Dec 2008
Posts: 4,511
syncerus
Extreme Tracker
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I'm happy with my ProChrono, and it appears to be the best inexpensive chrono on the market. I'll probably break the piggy bank and buy a Lab Radar next year, but there's no rush. The ProChrono isn't perfect, but really is pretty good.
NRA Patriot Benefactor & DSC Lifer
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Re: FPS without Chrono
[Re: bigjoe8565]
#6477600
10/03/16 12:18 AM
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Joined: Nov 2007
Posts: 9,523
RiverRider
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I used a Chrony for a long time. I guess it's better than nothing, but I watched a Youtube video where a guy ran shots through a Chrony and a Oehler 35 back to back. The Chrony reported average velocities within only a few fps of the Oehler, but the variance between the two on individual shots was a real eye opener (up to about 60 fps on individual shots). My conclusion was that the stats (ES and SD, in particular) which I have been logging over the years are very questionable at best. I found a reasonably priced 35P and now it's mine.
I guess the bottom line is something is better than nothing, and depending on your intent and how you want to use it, a cheap chronograph can get you by...but the old saying always will come back to haunt: you get what you pay for.
"Arguing with you always makes me thirsty." -Augustus McRae
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Re: FPS without Chrono
[Re: bigjoe8565]
#6477639
10/03/16 12:44 AM
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Joined: May 2014
Posts: 1,100
TackDriver
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I have the Oeheler35 for 18 years and still works, I only had to replace two orange sunscreens due to broken clips.
Last edited by Big Stan; 10/03/16 12:45 AM.
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Re: FPS without Chrono
[Re: RiverRider]
#6478973
10/03/16 09:13 PM
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Joined: Jun 2015
Posts: 5,923
Jgraider
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No, not at all. A gun doesnt blow up because you're two or three thousand psi over pressure. But, you can easily reach 70000 psi or more before pressure signs appear. Absolutely. Reloading without a chrono is not a great idea IMO if you're searching for a max velocity/max accuracy load. I can tell you that after loading for my 7mags for over 30 years, best accuracy is usually approaching max velocity/pressure. You can't find it without a chrono.
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Re: FPS without Chrono
[Re: bigjoe8565]
#6479014
10/03/16 09:34 PM
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Joined: Sep 2009
Posts: 18,954
ChadTRG42
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I would be lost without a good chrono. What makes it worse, is buying a cheap chrono, and getting wrong data, and going off of that wrong data. I use the chrono to tell me just as much info, if not more, than what my groups look like.
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Re: FPS without Chrono
[Re: bigjoe8565]
#6479164
10/03/16 10:53 PM
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Joined: Jun 2009
Posts: 1,884
jlsbassman
Pro Tracker
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Right now I'm using a prochrono, looking to upgrade. What are the suggestions for a new one in the 200-350 price range. The one I have now seems to be working ok but better to be safe.
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Re: FPS without Chrono
[Re: bigjoe8565]
#6479256
10/03/16 11:41 PM
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Joined: Dec 2008
Posts: 41,173
J.G.
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I work up looking for extractor marks. Once the load is decided I shoot to 800. Adjust MV in the calculator until the corrections match what I just shot.
800 Yard Steel Range Precision Rifle Instruction Memberships and Classes Available
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Re: FPS without Chrono
[Re: jlsbassman]
#6479320
10/04/16 12:17 AM
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Joined: Sep 2009
Posts: 18,954
ChadTRG42
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Right now I'm using a prochrono, looking to upgrade. What are the suggestions for a new one in the 200-350 price range. The one I have now seems to be working ok but better to be safe. For that price range, a Magneto is hard to beat.
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Re: FPS without Chrono
[Re: J.G.]
#6479416
10/04/16 01:11 AM
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Joined: Nov 2007
Posts: 9,523
RiverRider
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I work up looking for extractor marks. Once the load is decided I shoot to 800. Adjust MV in the calculator until the corrections match what I just shot. So, when you see extractor marks appear, what pressure level do you think you have reached?
"Arguing with you always makes me thirsty." -Augustus McRae
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Re: FPS without Chrono
[Re: RiverRider]
#6479546
10/04/16 02:34 AM
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Joined: May 2014
Posts: 1,100
TackDriver
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I bet its hot enough. I must have been a little bold when I worked a round robin test on Hybrid 100 V for the 6.5 Creedmoor, a few weeks ago,with the 30.5 inch barrel that the hottest load showed extractor marks when there was no visible signs on the Norma brass, primer pocket, or bolt lift. The muzzle velocity was 3160 with 140 Hybrids. Velocity is also an indicator of pressure.
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