Making major:

[SteveU]

This is an issue takes longer to write about than to solve, but I have a pretty specific scenerio I'd like to run past the gallery:

I shot in the A6 match (my first major match) with a new load. I practiced and chrono'd the load before the match. The load is:

VVN320 4.9 grains

Winchester Brass

Precision Delta 180 FMJ

OAL 1.185

WSP

KKM barrel

Dillon 650

I had worked up to this load and chrono'd it the the week before the match with a Shooting Chrony at 70 degrees at:

928, 960, 943, 955, 914, 945, 963, 927, 930, 919, 930, 920. Avg 936 fps PF 168 with a 180 grain bullet

At the A6 match, I hit the Chrono stage at 9:49 AM at 45 degrees with a bullet that weighed 181.2, and velocities of:

906, 918, 919. Avg of 3 was 914 with PF 165.7, which we all know is 165

Variables:

1) temperature

2) Chrono

3) ES of the first batch

4) MAYBE 1 charge a little light in the 2nd batch but didn't need to shoot enough to tell. Don't have a CED chrony to test.

With that data, obviously I could bump up to 5.0 to be safe for the Indiana State tournament in June. On the other hand, if it's the TEMPERATURE and not the CHRONO, my prior chrono results would suggest that I'm already safe with the 4.9 and might not NEED to bump to what would be around 175 or so.

Question: Should I bump up? (Would you?)

[jasmap]

Yes you can bump it up a little and you'll never even notice. Just bump it enough to average 170-172 PF.

[yoshidaex]

the 2 variables that come to mind are

1) the ambient temperature. a 25 degree diff is pretty huge

2) the chrono. a friend has the same chrono as you and it reads consistently higher than my CED millenium.

If you don't have time to chrono your loads, i'd say a bump of .2 grains should get you by.

Edited May 23, 2008 by yoshidaex

[LPatterson]

The Shooting Chrony is probably your main problem as the one I HAD read higher than a CED. For peace of mind I think I would bump it up the suggested .2 because N320 is not normally that temperature sensitive. I would give serious thought to replacing the Shooting Chrony with the new CED and 4' separation between screens.

[zhunter]

I for one would NEVER go to a match with ammo that chrono'ed at 168 PF!!!!!

171 is my minimum

I can't for the life of me remember which chrono I have, but I am ALWAYS very high at match chrono's.

:blizzard:

Edited May 24, 2008 by zhunter

[Joe4d]

One other variable, brass. seperate out enough similar brass IE all once fired remington, or all case trimmed CBC, enough to shoot the match and test and chrono. Then just check out everything else, You need to get your ES and SD down. You also might be glad your bullets weighed heavy. If the bullet was as marked you would have been 164pf.

[kframe_mike]

The Shooting Chrony is probably your main problem as the one I HAD read higher than a CED. For peace of mind I think I would bump it up the suggested .2 because N320 is not normally that temperature sensitive. I would give serious thought to replacing the Shooting Chrony with the new CED and 4' separation between screens.

I see I'm not the only one with a suspicious Chrony.Mine seems to read about 30-50 fps higher than the CED I compared it to.I'm going to ditch it and get a CED.I think the Chronys have 2 issues.First,I think the photo eyes are a little funky and second is the fold up design that could throw the distance between the eyes off.The distance between those photo eyes is very critical.I don't trust mine anymore.-Mike

[RePete]

My .40S&W ammo PF's at 177.6.

I want to make sure that I don't go under.

My 9mm PF's at 137.72.

[dansy]

I have a Beta Chrony in a drawer somewhere.....it was reading way high all the time, got myself a CED about a month after and never look back since, I see no reason to load at 177 PF it's just a waste of energy(uspsa only require 165).....I load at 168-170 (open) or so at matches that still use the chrony they usually think I shoot 178 PF

[RePete]

I have a Beta Chrony in a drawer somewhere.....it was reading way high all the time, got myself a CED about a month after and never look back since, I see no reason to load at 177 PF it's just a waste of energy(uspsa only require 165).....I load at 168-170 (open) or so at matches that still use the chrony they usually think I shoot 178 PF

I agree, but I know that I'll make PF regardless of the temperature.

Plus the recoil feel is fine too.

[eerw]

I'd probably bump it a bit.

seems more often than not..I ended up going to the chronograph when its cooler..

[SteveU]

Thanks, all. Good thoughts.

I was hoping for some magical combination of factors that would conclue that it's anything BUT my ammo being too close for comfort, but my conclusion is that my ammo is too close for comfort.

Good reality check.

[Jman]

Slight thread drift WARNING....

In defense of the F1 Shooting Chrony.

I too got some unexpected and erratic readings.

Moving it 8' away from the muzzle fixed that.

Had I read the manual (who reads stinking manuals)

I discovered that muzzle blast reaches the screens first.

This causes bad reads in that 4-6 foot range. Made sense to me.

That said, the CED is great for convenience and is worth it's price.

Trying to read the little numbers on the F1 at 8 feet is a PIA.

But for what? $79 it's acceptable. 2 cents deposited, thank you.

Jim M

[steel1212]

Moving it 8' away from the muzzle fixed that.

yeah but we where 10-12 feet away...

[G-ManBart]

N320 isn't all that temp sensitive, so I'm guessing it's either a difference in chronographs and/or that you're using mixed headstamp brass and aren't getting the most consistency possible.

168 is cutting it a little bit close unless you're really, really certain of your load. If you'd had that load at 170 you would have come in at 167 and thought "okay, a little close, but not a big deal". Bump that up a tenth or two until you get a consistent 170 with long strings (10 shots plus) and you'll be set.

I have a Shooting Chrony and we've run it end to end with my buddy's CED and shot over both at the same time. The two were within 10fps consistently and I just can't recall which one was higher. I like to put a target upside down on the skyscreens and that seems to help things out. I also use 15' as a standard. It gives me a touch more margin for error. Once you get your new load set, load an extra hundred or two. Set those aside, see what happens at the next big match, keep track of it and then use that extra ammo to calibrate your chrono if you're ever in doubt. R,

[dansy]

N320 isn't all that temp sensitive, so I'm guessing it's either a difference in chronographs and/or that you're using mixed headstamp brass and aren't getting the most consistency possible.

168 is cutting it a little bit close unless you're really, really certain of your load. If you'd had that load at 170 you would have come in at 167 and thought "okay, a little close, but not a big deal". Bump that up a tenth or two until you get a consistent 170 with long strings (10 shots plus) and you'll be set.

I have a Shooting Chrony and we've run it end to end with my buddy's CED and shot over both at the same time. The two were within 10fps consistently and I just can't recall which one was higher. I like to put a target upside down on the skyscreens and that seems to help things out. I also use 15' as a standard. It gives me a touch more margin for error. Once you get your new load set, load an extra hundred or two. Set those aside, see what happens at the next big match, keep track of it and then use that extra ammo to calibrate your chrono if you're ever in doubt. R,

Did the same with the Beta....some of the chrony are OK some are way off like mine that is the main problem I have with the chrony line....if they were all high or low that would be easy to adjust.

[SteveU]

N320 isn't all that temp sensitive, so I'm guessing it's either a difference in chronographs and/or that you're using mixed headstamp brass and aren't getting the most consistency possible.

I heard it wasn't (temp sensitive) and that's why I was pretty surprised to see the variation between chronos. I was using all "once" fired Winchester brass, but some OAL variation +/- .005 that I attribute to the round shoulder of the bullet (using Redding Competition seating die). This may be the reason for the ES. The only other thing I can think of is inconsistent return of the powder measure, but every random check I did was right on 4.9.

I went up to 5.0 (1 tenth) and I'll chrono at a local match this weekend. This weekend and the next major match are close enough timewise and geographically as well as late enough in the season that I shouldn't have QUITE as much temp spread between the readings this time. Hopefully that will eliminate that variable, regardless of how unlikely it is with my powder.

[steel1212]

N320 isn't all that temp sensitive, so I'm guessing it's either a difference in chronographs and/or that you're using mixed headstamp brass and aren't getting the most consistency possible.

I heard it wasn't (temp sensitive) and that's why I was pretty surprised to see the variation between chronos. I was using all "once" fired Winchester brass, but some OAL variation +/- .005 that I attribute to the round shoulder of the bullet (using Redding Competition seating die). This may be the reason for the ES. The only other thing I can think of is inconsistent return of the powder measure, but every random check I did was right on 4.9.

I went up to 5.0 (1 tenth) and I'll chrono at a local match this weekend. This weekend and the next major match are close enough timewise and geographically as well as late enough in the season that I shouldn't have QUITE as much temp spread between the readings this time. Hopefully that will eliminate that variable, regardless of how unlikely it is with my powder.

ummm so ya wanna use my chrono again? It works great when its getting ready to rain :-) I think you'll be fine with a .2 bump, if not we'll bring Pharoh Bender some blue MMs that should bribe him good enough to forget the low chrono lol.

[pjb45]

Chris,

VV320 is that sensitive to temperature change. I posted a thread about it here a year or so ago. The bottom line was the same gun, same ammo. One day cold, the following day was much warmer. There was a significant difference. I was using Pat's chrono. The only thing that was different was the temperature of the rounds and air. I forget if I was using the infrared ligths or just sunlight. Regardless, both days were sunny.

Surge, I use 4.9 of VV 320 in all kinds of brass, zero and montana gold bullets. In five nationals and two A2, it always chronos at 170-171. I use one load and make a boat load of ammo. The guy at Kodiak Precision is the technical rep for VV. He suggested that when I have a load that chono's major, to make extra and save it for the next big match. That way you always go to the match knowing it makes major rather than worring about it.

Also, as others have said, different chronos can give you variations in speed. Even the same chrono will give you variations it the light changes. The one thing that has helped me, was the National Chrono guys suggested putting a blast shield infront of the first screen. This has really helped me in getting a consistent reading.

[bkeeler]

This is an issue takes longer to write about than to solve, but I have a pretty specific scenerio I'd like to run past the gallery:

I shot in the A6 match (my first major match) with a new load. I practiced and chrono'd the load before the match. The load is:

VVN320 4.9 grains

Winchester Brass

Precision Delta 180 FMJ

OAL 1.185

WSP

KKM barrel

Dillon 650

I had worked up to this load and chrono'd it the the week before the match with a Shooting Chrony at 70 degrees at:

928, 960, 943, 955, 914, 945, 963, 927, 930, 919, 930, 920. Avg 936 fps PF 168 with a 180 grain bullet

At the A6 match, I hit the Chrono stage at 9:49 AM at 45 degrees with a bullet that weighed 181.2, and velocities of:

906, 918, 919. Avg of 3 was 914 with PF 165.7, which we all know is 165

Variables:

1) temperature

2) Chrono

3) ES of the first batch

4) MAYBE 1 charge a little light in the 2nd batch but didn't need to shoot enough to tell. Don't have a CED chrony to test.

With that data, obviously I could bump up to 5.0 to be safe for the Indiana State tournament in June. On the other hand, if it's the TEMPERATURE and not the CHRONO, my prior chrono results would suggest that I'm already safe with the 4.9 and might not NEED to bump to what would be around 175 or so.

Question: Should I bump up? (Would you?)

I chrono 10 rounds and all ten rounds must be above 916fps. The minimum for 165pf. The average of the 10 shots chronoed ends up being 947fps for a 170pf. @61*F But I am using 4.8gr TG and 180jhp MGB.

BK

[SteveU]

ummm so ya wanna use my chrono again? It works great when its getting ready to rain :-) I think you'll be fine with a .2 bump, if not we'll bring Pharoh Bender some blue MMs that should bribe him good enough to forget the low chrono lol.

Yeah, can you bring it Sunday? I'll just compare readings to the last time.

[steel1212]

ummm so ya wanna use my chrono again? It works great when its getting ready to rain :-) I think you'll be fine with a .2 bump, if not we'll bring Pharoh Bender some blue MMs that should bribe him good enough to forget the low chrono lol.

Yeah, can you bring it Sunday? I'll just compare readings to the last time.

Umm I'm guess you ment yesterday...when I was at the burkett class? If you want we could probably ask Micah sat to chrono it for you to make sure?

[SteveU]

ummm so ya wanna use my chrono again? It works great when its getting ready to rain :-) I think you'll be fine with a .2 bump, if not we'll bring Pharoh Bender some blue MMs that should bribe him good enough to forget the low chrono lol.

Yeah, can you bring it Sunday? I'll just compare readings to the last time.

Umm I'm guess you ment yesterday...when I was at the burkett class? If you want we could probably ask Micah sat to chrono it for you to make sure?

I figured. No prob. I'm fine. I'm using 'The Force' to determine velocity.

"You don't need to chrono this ammo."

"We don't need to chrono this ammo."

"This ammo is 170 PF"

"This ammo is 170 PF"

"Move along"

"Move along"