83FPS ES, is this chrony error or cheap brass?

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Kryogen

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I shot a group of 10 rounds of FC brass, reloaded with weighted charges (+- .02 grains).
All previously shot in my rifle, lee collet neck sized, no crimp
42.0gn of H4895
Rem 700P in AICS, 308

AV = 2663 FPS
83.81 FPS ES

84 FPS variation using the same brass and a weighted charge to +- .02 grains.
That's a lot to me.

So is this the chrony margin of error, or is it the cheap FC brass having too many variations?

What's the best ES you can expect from weighted charges 308 reloads?

Should I just dump the cheap brass and get myself 100 cases of lapua brass? Would be more uniform I guess?
And maybe I should get a magnetospeed and stop using that chrony ####?

(but hey, still, I shot a .33 MOA group at 200 yards. Best group ever at 200. Measured .66 inches.) Was windy. Not too bad.
 
Probably not the same batch.
Not weighted.

From post:
"Rem 700P in AICS, 308"

Funny thing, same load, same charge, with FC and Norma brass, I get a POI shift of 2 mils up and 2 mils right. That's quite a lot for just switching brands of brass. average velocity is the same +-4 FPS, shouldnt make such a POI shift at 200 yards.

Weird isnt it? Even if velocity is the same, I get a repeatable POI shift switching the 2 brands of brass.
 
Brass same lot #? Cases weighed and sorted?

83ES is not unusual, but not in match quality ammo.

Were you aiming at something the far side of the Chrony? The results are better if the bullet path is always the same.
 
It's just the way the cookie crumbles!
Remember, the advertising of the Chrony states there is a one per cent tolerance level, meaning in your case, within 26 fps of being correct is normal.
Another good reason for discrepancy in the velocities is the pressure of the load. Rifle powders are more efficient, ie, meaning more consistent, when they are loaded right up to what the cartridge was designed for.
Loading lighter can result in just what you describe.
 
should I load to max load then?
I was loading to 42, max is closer to 43something I think, I don't have my hornady manual right here. Should I load to max and see if the ES is better?

Cases do not have a lot #. Cases are not weighted.
Shots were pretty much all in the same line, but maybe it wasnt totally the BEST way through a totally horizontal chrony....
 
I would increase the load.
Also, in spite of all that is said about 4895 being a good powder for loading at less than normal charges, I have had poor results from lighter loads with 4895. I once wanted a deer load for my 30-06, so I loaded 150 grain bullets down to the 2500 fps range. I was a bit amazed when I tested them on the Oehler chronograph and found the es was in the neighborhood of 125 fps!
 
what should be a good ES for a match hand weighted load? I was expecting 20 or so... not 85.
Should I crimp to get a bit more resistance and more uniform velocities?

(it looks like federal gold medal match has an ES of 27 or so in 2 tests, so I would want at least 30 or so.....).

I'll make 2 tests next weekend. at 100 yards.

One, same load, but crimped with lee FCD, 10 shots
One, max load, no crimp, 10 shots
one, max load, crimp, 10 shots
will report ES and group size.
 
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A SPREAD OF 20 OR LESS WOULD BE GOOD. I don't believe the brass is the issue, brass should be all from the same LOT, conditions should be close sun or cloud, this can cause a shift in point of impact. While weighing include brass and bullets, also scope setting power will change things. Lots to check BUT consistency is key.
enjoy
 
OK, I'll give some examples from my notes.
Firstly, I shoot hunting type sporting rifles and the only times I weigh each load is when I am only loading about ten or less, of the same, then it is easier to weigh each one than it is to set the powder measure. By far the majority of my loads have the powder metered by my old Lyman Ideal #55 powder measure, which has been used extensively for over half a century.
This is from my old Husqvarna 30-06.
60 grains of Norma 204, low 2892, high 2923, ES 31. (Bullets were 180 grain Norma)

180 grain Norma bullets, 59 grains of Norma 204, Low 2803, High 2814, ES of 11.

And here is the light deer load I told about.
47 grains of IMR 4895, Low 2514, High 2656, ES 122.

And here I loaded eight of the same load, 165 grain Hornady bullet, 58 grains of 4350 and fired them four each, in two 30-06 rifles.
The four fired in a 30 Remington Express, basically a remnant of WW1, averaged 2778, with an ES of 19.
The four fired in my Swede, only dating back to 1950, averaged 2696 with an es of 24.

And I'll close with this 30-06 one for you, read it carefully. The powder, 60 grains of the modern H4831, yes the coarse stuff, was metered with the Ideal 55.
1 case was a RP, weighing 200 grains, - -- - vel. 2517
The next four were CIL Imperial cases averaging about 190 grains. vel------2495
2518
2501
2526 For av. of 2511, ES of 30
 
I suggest that you weigh the brass, after cleaning, so that you have a spread of 3gr either of mid weight range, and load in your usual way. Fire and then check you chrono results. Chrono on an overcast day.
 
Who cares what the ES is if the combo groups 0.33" @ 200... the proof of consistency is on paper, not in the air.

Sure, ideally the brass weighs exactly the same, with identical dimensions and your powder charges are precisely the same weight from the same lot, skimmed from the top of a settled can, and your bullets are perfectly uniform... it is not a bad thing to strive for all of that, but there is still a gun involved and a schmuck squeezing the trigger... there will always be grey areas...

Imagine if you had shot without the chrony... your post would have been a picture of that great group full of enthusiasm and excitement for your next range trip. Not a dejected, confidence-sapped post about the problems with equipment, that only serves to erode your confidence as you sight downrange...

I see the same phenomenon with fishermen using "electronic fishfinders." Rather than move when they aren't biting and putting together a working pattern, they hover over schools of inactive fish they see on the screen and waste their day trying to make them bite.

I use the chrony as a tool, another layer of info... but don't become it's slave... if you have a load that has an ES of 100 fps, but shoots your tightest and most consistent groups, go with the group result every time.

JMO
 
hoytcanon said:
Who cares what the ES is if the combo groups 0.33" @ 200...
Click to expand...

That's what I was thinking..
Add in the accuracy of the chrony is +/- 1% (26 fps)
You were only 42 fps each side of average (well within 95% STD)
You didn't give the data (just the Ave) so maybe there are some data points to ignore...

I would be happy with the grouping.
 
best group was .66 inches (.33 MOA),
I also tested some "dropped charges", and group was more like 1MOA, with even one round 100 fps more than the average. Probably a larger drop. i usually weight all match ammo because of this. it went flying somewhere else.... not in the group.Some of the dropped charges made good groups (had another group of 4 touching at 200y, but then a flyer half an inch outside). others not.

What I notice is that the effort to seat the bullet is not constant, even with norma brass. (probably not the same batch, didnt weight).


I will try all recommendations, including weighting the cases, larger charges, and crimping the bullets, will report, thanks.
 
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Funny thing, same load, same charge, with FC and Norma brass, I get a POI shift of 2 mils up and 2 mils right. That's quite a lot for just switching brands of brass. average velocity is the same +-4 FPS, shouldnt make such a POI shift at 200 yards.

Weird isnt it? Even if velocity is the same, I get a repeatable POI shift switching the 2 brands of brass.
Click to expand...

That's crazy. Over 14 inches high and 14 inches right over a brass change?
 
I've found the chrony much more stable either on a covered day, or late evening about 2hr before sunset, still enough light but none right on it, then it will read single digits, same load in bright sunlight it jumps all over the place +/- 30fps and/or errors.
I recently made a bigger sunshade to cover the whole thing for sunny days and it seemed to help some, I used 2.5mm corrugated plastic, its about $17 for a 4x8 sheet of the stuff. Makes a decent mirage shield for the barrel too.

Having matching brass from one brand like Lapua definitely helps.
 
It could be inconsistent neck tension. You could try annealing your brass or possibly crimping the loads will reduce that deviation.

Neil
 
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