Acceptable Powder Charge variance

The only methods and equipment with even the slightest possibility of reaching a valid conclusion might, and I say MIGHT, be Sierra bullet company or the likes of that. Barrels clamped in a 2-ton fixture, mounted on a 24" thick reinforced concrete slab, with 1000s of rounds fired down range.

Life is too short for the average person, no matter the extreme degree of the OCD.

The jury is in. No doubt for long.range and extreme long.range shooting the more accurately you weigh your powder the better your long range accuracy. Weighing to the last kernel is becoming more popular as rifles and shooters get more and more accurate.

Now there are many more variables out there that can keep you out of the 10 ring. If you aren't serious enough to address all that are in your control then you certainly don't need a $500 powder scale
 
Don't be disappointed when it doesn't. Because it won't.

I view this subject in the same way I view one-a-day vitamins. You can take one a day for your entire life, and on your death bed still never know if they were of any value.

There are too many competing variables to ever be able to determine the value to precision of 0.01gr powder weight tolerance versus 0.1gr powder tolerance. Spend your entire life trying to document the value contributed to precision, and still never know one way of the other. Might as well join the pets chasing their tails. Or maybe worse, chase fairy tales.

I think I should stop. Already used the sledge hammer. No need for a pile driver.

I think I more or less belong to this school of thought and I'm still just starting out so I have far more questions than answers but what I strive for is what I would consider practical accuracy. What I mean and try to find are the things with the biggest returns for my efforts. Things like keeping charge under 1/10 variance, seating depth within .001, shoulder bump, case capacity and so on. I don't know yet which factors are bigger than others but as I test I hope to learn and I would focus on those factors that showed me definite gains.
 
The smaller the case capacity, and the smaller the bore, the greater the variation in MV with small changes in powder charge weights.

Yesterday I fired 5 rounds each of two different loads in my .223 Rem. It's an AR-15. Everything except the powder charges were identical. The powder charges were weighed on a RCBS Chargemaster, to within 0.1 grain.

Weight-sorted Lake City cases, Rem 7 1/2 primers, annealed case necks, cases hydrosonic cleaned, outside necks turned & primer pockets uniformed & flash holes deburred with K&M tools, cases trimmed to same length & case mouths chamfered & case mouths polished with high rpm turning in steel wool after chamfering, HBN coated bullets, cases all resized with a Forster full length sizing die (custom neck honed to 0.2435" to avoid use of the neck expander after resizing), lubed interior case necks with Hornady Unique resizing wax and finally; all case necks crimped on the Hornady 60gr Vmax bullets with a Lee Factory Crimp Die after seating bullets to depths measured to within 0.001" from case head to Ogive.

First set of 5 bullets fired over triplicate chronograph setup:
27.0gr Hodgdon CFE223 . . . Avg MV 2877fps
Second set of 5 bullets fired over triplicate chronographs:
27.1gr Hodgdon CFE223 . . . Avg MV 2923fps

The 0.1gr difference in powder charge produced a 46fps difference in average MVs. If I ever experienced this with the cartridges and rifles I hunt game with at long ranges, I'd be interested in maintaining lowered tolerances on my powder charge weights. But I've never experienced such large changes in velocity with such small changes in powder charges in the larger capacity cartridges/calibers I hunt game with at long range.

Excellent chronograph conditions yesterday, and no recorded bullet velocity on the 3 chronographs differed by more than 2fps. In other words the extreme spread of recorded velocities for each of the 10 bullets across all 3 chronographs, was 2fps or less.

Of the rifle cartridges I reload, the .223 Rem is by far the smallest cartridge case capacity, and is the smallest caliber. This 46fps change in velocity for a 0.1gr change in powder charge is amazingly large, in my experiences, even with the .223 Rem. I've chronographed many bullet velocities in each of the following cartridges: .223 Rem, .280 AI, 7mm Rem Mag, 300 Win Mag, 30/375 Ruger Improved, 338 Win Mag, 338 Imperial Magnum, 338 Edge, 338 Lapua Improved, and 375 Weatherby.

I MAY see a 5fps change in MV for a 0.1gr change in powder charge in the larger cartridges, or I may not. A 0.1gr change in powder charge is on the threshold of causing a measureable change in MV in these larger cartridges/calibers, in my experiences. I've NEVER seen a 46fps change in velocity with 0.1gr changes in powder charge for 280 AI and larger capacity/bore cartridges.

I suspect the powder charges I weigh on my RCBS Chargemaster are generally measured to a tolerance within +/- 0.04gr, although I'd need a Gempro or something similar to really know. I trickle the last of the powder in with the Chargemaster, and stop when the digital readout changes to the intended XX.1gr charge weight. This would mean my powder charges would have been between 26.96gr and 27.04gr for the 27.0gr charge. And 27.06gr and 27.14gr for the 27.1gr charge.

The OPs initial post stated "I should note, I am not a competitor of any kind. I do take classes to be able to shoot long, but that is for hunting purposes, not competing."

I don't think the OP would benefit by controlling powder charge weights to 0.02gr even if he hunts with the .223 Rem. But if he hunts with the 270, 280, 30-06, and larger capacity cartridges most folks hunt with, the only purpose for measuring powder charges to 0.02gr would be for the satisfaction of being able to say you've set a goal, and attained it.

It's every person's right to decide which powder charge tolerance is acceptable, and to spend their money and time to achieve their chosen tolerance limit. At least in this country. Thank God for that.
 
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Just curious.

What was your ES and SD on those .223 rounds

I considered that prior to posting. The ES/SDs were not great. But I still felt it was tough to dismiss the fact that there was a large difference in MV.

5 velocities @ 27.0gr Hodgdon CFE223: ES 86 . . . SD 33

5 velocities @ 27.1gr Hodgdon CFE223: ES 47 . . . SD 20

I've spent a lot of time loading and shooting a variety of 60gr Vmax's over my chronographs, with 5 different powders, in the effort to obtain lowered ES/SD. I've been forced to the conclusion that the gas activated actions on the AR-15s cause larger ES/SD compared to fixed/bolt action rifles. It makes some sense to me. The bolt and bolt carrier in the AR-15 action are in motion while the bullet is still in the barrel, which creates another variable affecting the MV. At least that's what I've concluded.

Just so you don't think I'm completely full of ****, I started a Thread that evolved into that very topic. My posts in that Thread document a small portion of my efforts searching reduced ES/SD.
http://www.longrangehunting.com/forums/f111/hodgdon-varget-223-temperature-sensitive-161154/
 
I considered that prior to posting. The ES/SDs were not great. But I still felt it was tough to dismiss the fact that there was a large difference in MV.

5 velocities @ 27.0gr Hodgdon CFE223: ES 86 . . . SD 33

5 velocities @ 27.1gr Hodgdon CFE223: ES 47 . . . SD 20

I've spent a lot of time loading and shooting a variety of 60gr Vmax's over my chronographs, with 5 different powders, in the effort to obtain lowered ES/SD. I've been forced to the conclusion that the gas activated actions on the AR-15s cause larger ES/SD compared to fixed/bolt action rifles. It makes some sense to me. The bolt and bolt carrier in the AR-15 action are in motion while the bullet is still in the barrel, which creates another variable affecting the MV. At least that's what I've concluded.

Just so you don't think I'm completely full of ****, I started a Thread that evolved into that very topic. My posts in that Thread document a small portion of my efforts searching reduced ES/SD.
http://www.longrangehunting.com/forums/f111/hodgdon-varget-223-temperature-sensitive-161154/

The difference in velocity between your two owder charges is almost half of your extreme spread?

There is no validity to your test.

You are most definitely not in an accuracy node. An OCW test is in order.

With all the prep work you do and the results you are getting i would be disapointed.

I have an AR and my SD runs around 6. I found the secret for me was very accurate powder charges. Try trickling on a gempro to +/- 0.02 grains. With all your prep work you deserve better.
 
The difference in velocity between your two powder charges is almost half of your extreme spread? Correct for the 27.0gr Avg velocity. Not correct for the 27.1gr Avg velocity.

There is no validity to your test. Makes me smile. :) I seriously don't understand the basis for your statement. The test was valid, and the results/velocities are what they are. You might try to claim the velocity results are lacking utmost validity to support the cause and effect of 0.1gr change in powder charge on Velocity. I'd love to have SDs less than 10, but it hasn't happened yet. If the lower powder charge had produce 46fps higher velocity, then "no validity" would be correct - something flawed within the test.

With all the prep work you do and the results you are getting I would be disappointed. I've not been happy with the ES/SDs with the Hornady Vmax in this AR. ES/SD dropped by 66% when loading the Nosler 64gr Bonded Solid Base bullet. So I tried the same ingredients with the Hornady Vmax and again no luck. If you review my Posts in the linked Thread, you'll see I've already got plenty of time into load testing. Not hours - days. Tested multiple different powders and powder charges. KO'd with every effort with the Hornady Vmax, even though the bullet is very accurate in my rifle. One of the members who's owned 8 ARs says ES/SDs are normally higher due to the gas operated actions. I have to agree...

I have an AR and my SD runs around 6. Consider yourself blessed. It's not most normal from the searching I've completed on various Forums. My gun is accurate enough with almost each load I've fired in it. Some less than 1/2 moa. Almost all less than 1 moa. Good enough for what I use the gun for.

I don't believe 0.02 grain powder charges are going to get my SD down to less than 10. I've already got enough expense and effort into it. I still periodically test for lower ES/SD - more for knowledge/curiosity than a necessity with this rifle. If this was my sole long range hunting rifle, I'd work harder at it. Instead this rifle is for plinking, practice, home defense, and occasionally a ground squirrel.

Again, I've never seen such large changes in MV due to small changes in powder charge weights in larger capacity cartridges/rifles, having chronographed more than 1000 (perhaps 1000s) bullet velocities over the years.

Here's the details from the Oehler 35P, Oehler 33, and PACT PC^2 chronographs.

Charge . 35P . . . 33 . . . Pact
27.0 _ _ 2814 . . 2814 . . 2812
27.0 _ _ 2883 . . 2883 . . 2881
27.0 _ _ 2850 . . 2850 . . 2849
27.0 _ _ 2796 . . 2797 . . 2796
27.0 _ _ 2831 . . 2831 . . 2829
Avg 2834 fps . ES 86 . SD 33


Charge . 35P . . . 33 . . . Pact
27.1 _ _ 2908 . . 2908 . . 2908
27.1 _ _ 2884 . . 2884 . . 2883
27.1 _ _ 2862 . . 2862 . . 2860
27.1 _ _ 2862 . . 2862 . . 2860
27.1 _ _ 2886 . . 2888 . . 2886
Avg 2880 fps . ES 47 . SD 20
 
Opinions Vary

I built an 18" grendel. Checked velocities with factory hornady SST ammo to input into my kestrel with my V3. I was totally shocked. Ten shot test with an SD of 8. It is not an anomaly. Many on the grendel forum have the same results. Wonder how Hornady accomplished that.

I built it for hog hunting. Don't even bother to reload for.that one. That store bought ammo shoots great.

Now my 6mm AR turbo 40. Accurate powder charge among other reloading techniques make a huge difference. When it is right extremely low SD's and quarter inch 100 yrd groups
 
I have a chargemaster. Basically just use.it to throw powder charges and.trickle on a gempro. Sold mine on ebay this week. Found it.faster to use my gempro, lee dippers and.my little dandy trickler. It is also much more accurate

I believe you are mistaken on the accuracy of.your chargemaster. The link.below pretty much confirms my results. If that is good enough for you then so be it

http://www.longrangehunting.com/forums/f28/rcbs-chargemaster-accuracy-test-72153/
 
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