Should I bump up my load?

[bkeeler]

Question for the more experienced with chronos at major matches.

I have only shot 2 major matches this year and the chrono results have me baffled same lot of powder.

Home testing with ohler chrono indoors with lighted diffusers at about 60* average of 10 shot string is 171...pf. 4.850gr TG

First major of the year it was hot 80-90* and they were using 2 chronos average 3 rounds 177PF

Second major using 1 chrono temp around 65-70* average for 3 rounds 167PF. Everyone else in my squad at this match was low too.

Should I bump my load up a little or leave it? I have one more major coming up in October sure don't want to go minor.

Thanks in advance.

BK

[BritinUSA]

Past two Nationals I have been around the 165 mark (just over by a hair) but over 172 in Colorado. Not sure whether it's altitude, heat, cold, humidity or just general voodoo but I always get significantly lower readings at Nationals. I was chrono'ed at the Mile High last weekend at 175 so I am hoping for less drama at Nationals this year.

[BMartens]

Question for the more experienced with chronos at major matches.

I have only shot 2 major matches this year and the chrono results have me baffled same lot of powder.

Home testing with ohler chrono indoors with lighted diffusers at about 60* average of 10 shot string is 171...pf. 4.850gr TG

First major of the year it was hot 80-90* and they were using 2 chronos average 3 rounds 177PF

Second major using 1 chrono temp around 65-70* average for 3 rounds 167PF. Everyone else in my squad at this match was low too.

Should I bump my load up a little or leave it? I have one more major coming up in October sure don't want to go minor.

Thanks in advance.

BK

It looks like you have seen both extremes. 167-177 is a pretty good spread even with the temperatures noted. Was there any significant variation on the bullet weight?

If that was my load I believe I would just leave it alone. I think your next results will be somewhere in between.

[bkeeler]

Was there any significant variation on the bullet weight?

No.

BK

[Mistral404]

I usually do a 171 PF at high altitude on a warm day-80 degrees. I use VV 320. I have never failed to make major. At Tulsa last year, same gun, same ammo back to back Nationals, on the cold day I had a 167 PF and on the warm day I had a 171.

If you cut it too close you will end up minor. If you bump it up too much and you are doing a 181 PF.

The VV technical rep said go minimum plus 5 and you should be safe no matter where you are shooting.

Remember your chono is more accurate than what is used at most Area matches. A2 does it like Nationals, two chronos and a lighted box. Even then each chrono posted significantly different velocities, that is why they use the highest reading for each shot. Some area matches only use one chrono. Again, this is just to warn you not to cut it too close to the 165 PF.

[CocoBolo]

Those Chrono results baffle me, Tite Group gets hotter the cooler it gets. I bumped my load last year for the Gator 200gr 40 to 4.4 gr from 4.3 @ 172 and it hit 189pf at the match at about 60 degrees. The bad thing was the gun was a real had full of flip at the match.

At the TX Limited that August hotter than h it only hit 168pf @ 95 or hotter.

I would just ride with it.

[AZ38super]

It all depends on how your poweder reacts to temp changes.

My advice...

Stop trying to just make major and make the load work for your gun.

I made my loads around 171-173 pf but I found out one day testing loads if I added a tenth or two of powder to my load that my dot did not move or jump at all.

Just making pf may not be the load you want to use....

[G-ManBart]

Past two Nationals I have been around the 165 mark (just over by a hair) but over 172 in Colorado. Not sure whether it's altitude, heat, cold, humidity or just general voodoo but I always get significantly lower readings at Nationals. I was chrono'ed at the Mile High last weekend at 175 so I am hoping for less drama at Nationals this year.

I've said this many time before, but last year I loaded a batch of ammo for Nationals, Area-2 and a Sectional. It was one lot of new cases, one lot of powder, bullets from the same box from MG and primers from the same sleeve. That batch went 171PF the first time I chrono'd it, but I didn't get to put as many rounds over the chrono as I usually do (20x2). At Area-2 it went 174PF. After I came back from Nationals I ran it over the chrono again and got 175PF. I recently tried it again (saved the last 100 or so), two strings, and got 174 and 175PF. At Nationals it was 166.1PF

I had a solid load, using a powder not known for temperature sensitivity (N105), it was easily over 170PF every time I tried it, and it still just squeaked by at Nationals.

I recently loaded up my Nationals ammo using the same lot of powder as last year (bought a bunch of it), bullets from the same shipment (different box), new cases (same brand etc) and slightly different primers (FSPM instead of FSR) and it ran 174PF and 175PF both times I tried it (20 round strings). I can't wait to see what this runs over the Nationals chrono because it's been a pretty consistent 174-175 except for the 08 Nationals and the first abbreviated chrono session.

I will add that I've put my chrono in line with a CED chrono to compare and mine was a consistent 10fps faster (several guns and loads) than the CED, but there's probably that much difference between two identical CED's so I doubt it was a factor.

Edited September 6, 2009 by G-ManBart

[VegasOPM]

Plan for high temps for your loads for this Nationals. The range temp will be 100+ during the middle of the day- 90+ in the morning. On most powders that means higher velocity. Of course I use 4756, so the opposite is true. I have had the exact same load, primers, batch of powder (measuring every 100th drop to verify that the powder drop was the same) and bullets chrono at everywhere from 166 to 178pf- depending on the chrono and temp. Thankfully even at 166, I am still making major.

[shooterbenedetto]

Rule of thumb for me, I always go 3pf more just to be at the safe side.

168pf is good...BUT MY GUN WORKS WELL AT 172PF 9 major.

Edited September 6, 2009 by shooterbenedetto

[Cardinal]

I had a solid load, using a powder not known for temperature sensitivity (N105), it was easily over 170PF every time I tried it, and it still just squeaked by at Nationals.

From what I've heard around here in Norway, N105 is considered somewhat temp sensitive.

I know one who used 105 and chrono'd it to around 170-175 (can't remember exactly), but at a level IV or V match in Asia or South America where it was a lot warmer, he ended up at 159.something and Minor!

[boz1911]

My open load has checked 173+ at 4 major matches this year. It wil be interesting to see how it reacts in the 100 degree heat. I'm using HS-6 and I don't know how it reacts to temperature changes.

[TwoShot]

I use Silhouette in a major 9 open gun which I have found to be reverse temperature sensitive.. My load at home is 167 p.f. I recently shot a major match and didn't want to take chances. I bumped it up to 171 p.f. and checked it on two different chrono's. At the match I chrono'ed 169, this surprised me at the moment because there was little temperature difference when I had chrono'ed at home. The question was answered when the match official handed me the bag with my leftover ammo. It was "extremely" hot. It seems my squads ammo had bee left out on a table in full sun while the chrono guy's had lunch. No harm done but you need to factor in those kind of unknowns.

[atbarr]

It seems my squads ammo had bee left out on a table in full sun while the chrono guy's had lunch. No harm done but you need to factor in those kind of unknowns.

IMO, to be fair to all , the ammo should be left under a table or in the shade.

A.T.

[G-ManBart]

I had a solid load, using a powder not known for temperature sensitivity (N105), it was easily over 170PF every time I tried it, and it still just squeaked by at Nationals.

From what I've heard around here in Norway, N105 is considered somewhat temp sensitive.

I know one who used 105 and chrono'd it to around 170-175 (can't remember exactly), but at a level IV or V match in Asia or South America where it was a lot warmer, he ended up at 159.something and Minor!

That hasn't been my experience, but I haven't done a lot of true low temp testing with N105. I've chrono'd it anywhere from around 7*C up to 37*C or so and if anything, it seems to be slightly positively temperature sensitive, but not much. In fact, when I chrono'd at Nationals it was very close in temp to what it was when I checked the load before leaving home....which really didn't make much sense to me. R,

[bkeeler]

Too be on the safe side I bumped my load to 5.0gr from 4.850gr. The way I am looking at is that I will not be able to tell the difference while shooting it and a little more cushion won't hurt. This should give me around 173-174PF I will chrono to confirm.

Thanks for the advice.

BK

[Will_M]

It seems my squads ammo had bee left out on a table in full sun while the chrono guy's had lunch. No harm done but you need to factor in those kind of unknowns.

IMO, to be fair to all , the ammo should be left under a table or in the shade.

A.T.

How does the chrono process work at major matches? Do you hand in your ammo to be chrono'd (all the ammo you brought?) and the chrono officer shoots it through their gun?

[bbbean]

How does the chrono process work at major matches? Do you hand in your ammo to be chrono'd (all the ammo you brought?) and the chrono officer shoots it through their gun?

You give the RO your gun and an empty mag. He loads the ammo you turned in earlier and shoots it over the chrono.

[L9X25]

Fairly simple way to test out a theory ... Load up 30 rounds using the powder in question. Place 10 in a cooler with ice, 10 in your pocket, and the final 10 under the hood of you car when you arrive at the range. Chrono the pocket, cooler and finally the hot rounds and note any variation in velocity. Make sure that the slowest of the 3 makes major. IIRC 452AA speeds up in cold weather and others are the opposite. Many (541) don't care about temp at all. Matches like the Florida Open make this necessary, the temps in February can vary from 20 degrees to 90 degrees on any given weekend.

[LPatterson]

How does the chrono process work at major matches? Do you hand in your ammo to be chrono'd (all the ammo you brought?) and the chrono officer shoots it through their gun?

At most major matches the RO will collect 8 rounds on the first stage that you shoot, sometimes before you shoot & sometimes after the stage as you sign your scoresheet.

[Aircooled6racer]

Hello: I made up my Production ammo for a while. I chronoed it here in Albuquerque on multiple days to make sure it makes the power factor of 125. It is 131Pf on multiple days at temps between 70-90 degrees. It varied very little. At the nationals it chronoed 133PF at 90 dgrees. The thing I was wondering with some others over dinner one night was. If the chrono box is painted black(at nationals it was) would'nt the temperature inside the box very depending on sunlight and ambient temps? Also would that efffect the electronic stuff inside the box? The temps inside the box would have to vary alot maybe going as high as 140 degrees just like a closed up car in 90 degree weather. I passed the chrono since I loaded to simular conditions as the match conditions. Others were not so lucky. Makes you think--I think Thanks, Eric