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someone with Quickload run a couple scenarios?

cali_tz

cali_tz

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Full Member
Minuteman
Oct 4, 2010
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NorCal
I'd like to understand the effects of my RCBS Chargemaster being accurate to the 0.1 grain.

So can someone with Quickload tell me what the difference in MV would be between say 44.0, 43.9 and 44.1 grains of Reloder 15 powder. Pick a 308 case size that you know of, Fed 210M primer, and a 26" barrel. I am just curious as to how big of a difference is predicted when you are above and below your target powder by 0.1 grains. If you could also do the test at 43.95 and 44.05 just to see the difference of half of the stated accuracy that would be great, many thanks.
 
Re: someone with Quickload run a couple scenarios?

quickload is not accurate enough to provide that type of data ( and have that data be reliable)

i wouldn't even trust a chrono to tell me something like that.

you could easily have a variance in case capacity that would neglect/offset any idea's of a .1 differece in charge weight.

and then there's variations in BC's , effects your exterior ballisitis.

but a .1 difference , it can't be anymore then 20 fps , probably less 10 , even 5 , i wouldn't be surprised if you had varying charge weights of .1 and still had a low ES/SD

why kind of scale are you using ?
 
Re: someone with Quickload run a couple scenarios?

why is this a no-no?

I am using an RCBS Chargemaster which incorporates a RCBS 1500 digital scale. I believe its stated accuracy is 0.1 grains, but is that +/- 0.1 grains or a total of 0.1 grains which would +/- 0.5 grains? If it's +/- 0.1 grains then from one round to the next we could have 0.2 grains difference in powder. Looking last nite at how many grains of RE15 makes up 0.2 grains, it's not alot obviously, but it's not 2 or 3 particles either. So I am just wondering if you were to take the Chargemaster at its word and use only loads that said, in my case, 44.0 grains... what MV ES would you end up with, if all case internal volumes/neck tension/primer/everything else was equal.

I thought Quickload could provide some insight into this theoretical scenario.
 
Re: someone with Quickload run a couple scenarios?

There is a rule here against asking someone to run Quickload data for you. It was instituted because the folks that sell the program would rather you buy your own copy than mooch of those that have.
 
Re: someone with Quickload run a couple scenarios?

ok, makes sense. well then don't give me any info from QL... but any insight to the core question would be interesting.
 
Re: someone with Quickload run a couple scenarios?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: cali_tz</div><div class="ubbcode-body">ok, makes sense. well then don't give me any info from QL... but any insight to the core question would be interesting. </div></div>

Resolution is .1 grains, accuracy is usually expressed as '+/-' X, Y or Z.

Like the guy above said, .1 grain in most rifle carts isn't going to amount to much of an increase/decrease in FPS. It's probably greater for pistol carts.

Any difference noted could/can be attributed to various reasons, such as inconsistent neck tension, temperature of the barrel as cycles heat it up and expand the bore, changes from primer to primer, in the amount of spark, et al..

Chris
 
Re: someone with Quickload run a couple scenarios?

This is probably going to sound stupid because I may not get it worded correctly. Sit down with a really good digital scale, loaded (for example) 43.9 grains of powder and then slowly added one kernel at a time until the scale read 44 grains. How many kernels did it take? Then, add one kernel at a time until the scale reads 44.1 grains. It surprised me just how much difference in kernels you can have inside that 43.9 or whatever grain charge.
Now, if I didn't loose you, seeing that there can be enough difference inside that .1 grain to effect your 43.9 grain load, why not just take time to ensure that all your charges weigh the same each time. I never vary charge weight from the one I want. Not even in one round. Believe me, at long ranges, it will make a difference.
 
Re: someone with Quickload run a couple scenarios?

well it's nice to say that each throw reads 44.1 grains, but that is absolutely never the actual weight. When you say 'really good digital scale' ... what is really good? Tell me an accuracy, and tell me the brand of scale that gets that accuracy.

The RCBS 1500 accuracy is +- 0.1 grains. So even if every throw stabilizes on 44.1 read out, the actual weight being measured can be, according to the stated specification, anywhere between 44.0 and 44.2 grains.

So back to my original question, assuming every other factor is the same (neck tension, primer, everything) in a Win 308 piece of brass, and the only variable was a 0.2 grain swing from shot 1 to shot 2... would be the difference in MV between shot 1 and shot 2. If it was 10fps or less, that would be great to know.

If 0.2 grains causes like 30-50fps, that would be good to know too.
 
Re: someone with Quickload run a couple scenarios?

I use a RCBS 1500 but I also have check weights and a beam scale to check it by.
Here is an example of some chrono data on my 308. The powder charges were weighed on my RCBS Chargemaster:
308 Win
175 SMK
FGMM primer
Lapua brass (match prepped)
2705
2726
2742
2739
2736
Average velocity is 2730, extreme spread is 37 FPS and SD is 12 FPS.
This data was recorded at 68 degrees.
I have never in all my years of using a chrono (and no matter how charges were weighed) had five rounds provide the exact same velocity. I don't think I ever will. So what you are asking here is likely a moot point. My point was that you should make every load the same according to readings your scales, etc are providing.
 
Re: someone with Quickload run a couple scenarios?

well you didn't quite answer my question directly, but it's interesting to see your data. Your ES and SD is quite good, in my experience reloading the exact same configuration. I get lots of DUPS on my CED chron. I don't have a good theory on why, because like you I think it's highly unlikely.

Thanks for posting your data. Now it would be interesting in Shooter to see what difference in drop, at say 1000 yards, a change in 37fps would cause?
 
Re: someone with Quickload run a couple scenarios?

And now lets say your chrono has +/- 1% error and the chrono reads 2600fps...is it really 2600fps? Or is it 2574fps? Or 2626fps? Or somewhere in the middle? Personally, I only use a chrono to give me average muzzle velocity. I let the target tell me the rest. Sure, I look at the ES and SD, but don't really pay them much attention.

FWIW, I've tried (not very hard...but tried some, anyways) to find major chronograph manufactures acceptable margins of error only to find that they don't publish that information. I use the 1% mentioned above because it seems reasonable to me that is what it "could" be....
 
Re: someone with Quickload run a couple scenarios?

Then I am not sure what your question is.
My point of posting the data was to show you that even when I carefully prepped my brass and removed all variables I could in loading that ammo I still saw a 37 FPS extreme spread. Now, how the hell will you ever know if that extra kernel or .1 grain of powder caused a variation in FPS? BTW, the load I use as an example will and has provided 1/2 MOA consistently [not all day long
smile.gif
] out to 600 yards.
Again, I have to say, you are the one missing something here. I am trying to tell you remove ALL the variables you can. That includes measuring every charge the same, If you want 44.1 in every case then put 44.1, no more or less, in every case.
Also, at shorter distances, I would think that if you are in an accuracy node that the .1 grain difference shouldn't take you out of the node.
 
Re: someone with Quickload run a couple scenarios?

A calm day and keen brass prep is in order, but the best test is to go out and shoot a long string at 600 yards (or farther) and take an average of say 20 shots varied 0.1 grains at a time.

You could then extrapolate an average of 0.1 grains.
It will track left and right but a patter will emerge.

Bet you buy a Denver scale when your done
smile.gif


Peace
 
Re: someone with Quickload run a couple scenarios?

@shoot4fun, you can't really remove variables when those variables are inherently somewhat random. 44.1 on the RCBS scale doesn't mean 44.1 but somewhere between 44.0 and 44.2, and 2600fps doesn't mean 2600fps (as sawgunner correctly points out), and so on and so forth.

At the end of the day, if you have a load, however developed, that shoots 1/2 MOA all day, then all this discussion is moot. However, I am NOT there at ELR distances, and so I am trying to understand what are the important sources of variation in the load and how to remove them. I understand my shooting skills are one of those variables. I would also bet that you are right in that 0.1 grain difference won't substantially affect the accuracy node, esp after reading the following....->

I found this thread elsewhere about OCW (http://optimalchargeweight.embarqspace.com/) and some further thoughts on why OCW works (http://www.the-long-family.com/shock%20wave%20theory%20summary%20explanation.pdf). These are definitely worth a quick read. Alot of what I found in reloading I find validated in these websites. And I will try their method for finding the OCW. Ideally I'd like to calculate a starting point using Quickload and barrel length and see how that changes things.
 
Re: someone with Quickload run a couple scenarios?

The info you posted is just what I was trying to tell you (probably didn't communicate that too well, sorry). Once you do the OCW and find the right node very minute variances in powder charge caused by scale inaccuracy won't (shouldn't) have any adverse impact on performance.
I was taught OCW by a well respected rifle builder on his white board but the first site you linked is so good I have book marked it. Thanks!
Good luck and happy shooting, my friend!
 
Re: someone with Quickload run a couple scenarios?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: shoot4fun</div><div class="ubbcode-body">
308 Win
175 SMK
FGMM primer
Lapua brass (match prepped)
2705
2726
2742
2739
2736</div></div>

Using this data in JBM at the high and low velocity:
2705fps 1000 yds 37.4 moa
2742pfs 1000 yds 36.2 moa
Thats a 10.2" difference in elevation.
2705fps 1500 yds 87.6 moa
2742fps 1500 yds 84.9 moa
Thats a 40.5" difference in elevation (roughly).

It's pretty easy to see what a change in velocity will do to your elevations at distance.
 
Re: someone with Quickload run a couple scenarios?

Goin'Hot... thanks for posting. Now the question is ... how much powder (for shoot4fun's example) difference does it take to cause his 175SMK to go 2705fps vs 2742fps...?

I am shooting at 1500+ with my 338LM and 40"+ is the difference between hit and total miss, obviously. I think OCW concept definitely is valid, and mutually exclusive with reducing MV spreads. OCW may help to dominate group size at small distances (<500) where the barrel harmonics dominate the bullet dispersion, compared to dispersion caused by 30-40fps of bullet variation. However at long distances where the bullet slope starts to get really steep due to non linear acceleration downwards, as your analysis shows, perhaps the MV spread starts to dominate bullet dispersion. So once we nail down the OCW, then we still have to chase reducing MV spread.

I am hoping that the inherent max 0.1 grain inaccuracy of my RCBS 1500 is the reason for perhaps a 10fps difference in MV. And that any further spread with MV has to do with differences in neck tension (which I don't know how to control other than some neck turning exercises).
 
Re: someone with Quickload run a couple scenarios?

It's not just a powder charge weight or neck tension issue. If the brass weights different, that means there is a volume difference inside of the case and that will cause a change in velocity due to pressure. Primers are also not 100% the same from piece to piece. Slight differences in the bearing surface of the bullet will also cause a velocity change. Quality components make a difference but, you can only do so much.
 
Re: someone with Quickload run a couple scenarios?

Food for thought Cali, on a recent ladder test I had 4 shots @ 300 with 4 different powder weights starting at: 45.6,45.9,46.2,46.5 of h4350. The vertical was .6 of an inch. The velocities were: 2966,3001,3014,3004.
The last velocity was probably a chrono hiccup. As you can see .9 of a grain had decent vertical. The accuracy of your ammo with a +/- .1 of a grain will shoot very well. These examples were the high node for this rifle/load combination.
 
Re: someone with Quickload run a couple scenarios?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Goin'Hot</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: shoot4fun</div><div class="ubbcode-body">
308 Win
175 SMK
FGMM primer
Lapua brass (match prepped)
2705
2726
2742
2739
2736</div></div>

Using this data in JBM at the high and low velocity:
2705fps 1000 yds 37.4 moa
2742pfs 1000 yds 36.2 moa
Thats a 10.2" difference in elevation.
2705fps 1500 yds 87.6 moa
2742fps 1500 yds 84.9 moa
Thats a 40.5" difference in elevation (roughly).

It's pretty easy to see what a change in velocity will do to your elevations at distance. </div></div>

WOW! When you put it that way maybe I'm not such a bad shot after all. You know, after doing a lot of reading and some shooting at 1000 with a couple of different calibers, I think the 308 is lacking when compared to the 260, 7MM-08 (168 gr bullet) and even the 243 (115 DTAC). I certainly shoot much better at that distance with the 7MM-08. Come to think of it, my velocity variance and SD are much lower with it too.
Now, as far as loading goes, my brass is weigh sorted to within .4 grains, and I keep a close eye on powder charges and seating depth too.
 
Re: someone with Quickload run a couple scenarios?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Rthur</div><div class="ubbcode-body">Food for thought Cali, on a recent ladder test I had 4 shots @ 300 with 4 different powder weights starting at: 45.6,45.9,46.2,46.5 of h4350. The vertical was .6 of an inch. The velocities were: 2966,3001,3014,3004.
The last velocity was probably a chrono hiccup. As you can see .9 of a grain had decent vertical. The accuracy of your ammo with a +/- .1 of a grain will shoot very well. These examples were the high node for this rifle/load combination. </div></div>

That's interesting... I really wonder if that was a chrono hiccup or was there a seating or primer difference... I always have to justify irrational chrono numbers like this too. It's like whackamole with reloading... you think you are onto a logical trend and then your chron tells you something very unexpected.

I would have thought you would get more vertical dispersion than that... does that 0.6" agree with a ballistics program prediction?
 
Re: someone with Quickload run a couple scenarios?

I'm taking some libertys here since Rthur doesn't state what caliber or bullet. Assuming he's shooting a 6.5x47 with 123 Amax bullet.......

2966 fps at 300 yds 3.6 moa
3014 fps at 300 yds 3.4 moa

That claculates to a drop or difference of 0.6"
 
Re: someone with Quickload run a couple scenarios?

Sorry Cali, that load is for a 260 with berger 130 vld. The seating was checked with a comparitor on these loads. My ballistic info is from KAC bullet flight. I just believed what the bullet was telling me. I am going to test this node at greater distance when I can get time and better weather. My short range is well protected and helps with load testing @300 and 400. With the numbers on my load I will be testing in what looks like the middle of the node. That way any small variance in powder charge will be absorbed by my inaccuracies. btw those chrono numbers were from a oehler 35p.
 
Re: someone with Quickload run a couple scenarios?

Thanks... I would love to compare the CED vs Oehler, have them one right behind each other and see what the difference in reported speed is...
 
Re: someone with Quickload run a couple scenarios?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: cali_tz</div><div class="ubbcode-body">Thanks... I would love to compare the CED vs Oehler, have them one right behind each other and see what the difference in reported speed is... </div></div>

I have not tested CED vs Oehler but did one a while back testing the PACT against an Oehler 35P. The velocity data was quite close. If any difference at all it was within a couple of FPS. At the time this was a comparison of a $100 unit to a $350 unit.
Now, here is where the big difference is. It's in the eyes. THe 35P will work accurately in conditions the PACT will not work at all in. It has also been my experience that this holds true when comparing 35P to CED.
 
Re: someone with Quickload run a couple scenarios?

Thanks, that's interesting data.
 
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