Load development ...




Gwain

New member
#81
I’m not sure that I understand your process. If you will help me by addressing the following questions, I'd be greatful:
  1. Do you start with a profile that indicates charge range for your ladder test and then, using the node from the ladder test, modify your QL profile to match the node? Or, do you run an arbitrarily selected range of charges in your ladder test and then build your QL profile around the node you find?
  2. What is an OBT calculator?
  3. What are 3.5 and 4.5 half mark nodes?
Thank you for your support.
Go here get calculator. http://www.the-long-family.com/optimal barrel time.htm

You can input barrel length and node start point. To get the half node, change first node to -.5. That is a negative .5. These barrel times are what you match to OBT in QL. I can use QL and load manual to develope starting load. Typically run 3 or 4 charge weights in .3 grain increments. Once fired I have fired case H2O capacity and velocities to help true QL. Now I can find the OBT that is under max, typically the 4.5 node and then I load across that node. So if QL says 42.5 is the node I run 42.4, 42.5 and 42.6 to find the actual accuracy node the rifle likes. I can finish by running seating depth test once I have the charter weight. Hit node inside 50 rounds last time. So I kinda use the velocity ladder and QL together to build profile and find optimized load.

Screenshot_20190118-110752_Hancom Office Cell Viewer.jpg
 

LongRange

Obsessed Member
Forum Supporter
#83
I’m not sure that I understand your process. If you will help me by addressing the following questions, I'd be greatful:
  1. Do you start with a profile that indicates charge range for your ladder test and then, using the node from the ladder test, modify your QL profile to match the node? Or, do you run an arbitrarily selected range of charges in your ladder test and then build your QL profile around the node you find?
  2. What is an OBT calculator?
  3. What are 3.5 and 4.5 half mark nodes?
Thank you for your support.
Gwain is my buddy i said id get over here...as you can see hes into QL as well.
 

LongRange

Obsessed Member
Forum Supporter
#84
Thanks for asking about that. I don’t use any purpose built custom target rifles. So, I’m not concerned about reamers and free bore. Every rifle I have, with exception of two, are factory Rem 700s with premium triggers. One exception is a 300 WM that was built with a premium quality chasis, action, barrel, and trigger. It consistently shoots .3 MOA. I also have a factory stock Rem 700 300WM that consistently shoots .4 MOA. The custom rifle cost five times more than the factory rifle. Was it worth it? No. The other exception is the RPR 6.5 CM that we will use for the test. It now has a recently installed Proof Concept barrel on it, otherwise it's all factory stock.

fair enough.

I don’t accept everything that QL comes up with. It’s just a tool. Although it’s a really nice tool for cartridge design and charge estimation, it isn’t absolute. Using QL eliminates having to run dozens of combinations of variables in order to find a cartridge design “sweet spot” to go test.
I chose .040 off of the lands from a seating depth test. See attachment. I can go to 2.850 before I’m on the lands. To be at.025 off of the lands I’ll use a COAL of 2.825. The test result indicates that 2.830 – real close to 2.825 - might have been a better choice than 2.810 (.040 off lands). I chose 2.810 because the ES (19) and SD (7) were better than the 2.830 ES (33) and SD (14). I’ve been kicked too many times by simply choosing the load that makes the best group or least vertical spread. So, in the past couple of years, I’ve chosen the load that has the lowest ES and SD provided the group size is .5 MOA or less.

To get to 3/4s of the way, the COAL would to be 2.890. Can’t accommodate that. The test COAL of 2.825 (.025 off lands) leaves 100% of the bullet shank in the neck.

you misunderstood what i meant by 3/4 in the neck but thats ok because you have enough bullet in the neck with the chamber in your RPR.

In summary, I’ll run charges (H4350) ranging from 41.0 gns to 42.8 gns in steps of .2 gns. Components will be NEW Lapua brass, GMM 205 primer, SMK 142 bullet. COAL will be 2.825 for .025 off of the lands.

Sound okay?

Thanks again for your support.

curious to see/hear how this works out...im betting you find a better node with better numbers higher in the charge weights.
now as far as selecting the best group goes...when i shoot my load developments im looking for 3 groups that are near the same but more so close in numbers i then pick the middle node(most times)because if it gets hotter or colder that center load will shoot pretty much the same.
that said i have been known to shoot a little looser load if its fast....no sense running a top fuel dragster on pump gas.
 

rw blakemore

Member
Forum Supporter
#85
Go here get calculator. http://www.the-long-family.com/optimal barrel time.htm

You can input barrel length and node start point. To get the half node, change first node to -.5. That is a negative .5. These barrel times are what you match to OBT in QL. I can use QL and load manual to develope starting load. Typically run 3 or 4 charge weights in .3 grain increments. Once fired I have fired case H2O capacity and velocities to help true QL. Now I can find the OBT that is under max, typically the 4.5 node and then I load across that node. So if QL says 42.5 is the node I run 42.4, 42.5 and 42.6 to find the actual accuracy node the rifle likes. I can finish by running seating depth test once I have the charter weight. Hit node inside 50 rounds last time. So I kinda use the velocity ladder and QL together to build profile and find optimized load.

View attachment 38652
Thanks … very happy to hear this! Your approach is essentially what I have been doing for the past few years. Before I found Long’s OBT work, QL results were hit or miss at best. Using Long’s OBT and revised QL burn rates make QL work. I haven’t used a load manual in years.

Knowing what node velocity I want and an approximate charge, I'll shoot 4 rounds each of 4 different charges. Using the charge that runs closest to desired velocity I try 4 shots each for three different neck tensions. Choosing best combined result from charge and neck tension evaluation, I then shoot a spread like that shown to find the best seating depth (see attachment). That’s another 25 rounds. Total rounds fired, 53.

It seems we're on the same page.

I can’t find the OBT calculator on the web. Can you give me the link? I still use Long’s table to pick off node values. I’d like to see how the table compares to the calculator.

Seating Depth.jpg
 
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rw blakemore

Member
Forum Supporter
#87
i know you use quick load because i know how it works and by the info your posting....we will just have to agree to disagree about quick load...personally i think its a waste of time but then again like i said im always looking for ways to cut loading times not spend more time to get to the same end result.

in your creed why are you running .040 off the lands? because QL told you thats OBT im guessing? or so you can load in a mag? also if your compressed at 41.7g+ do you know the freebore of the reamer that was used to chamber that barrel?
it must be short because most saami/match reamers are .199-.188 free bore which would leave you with not much bullet in the neck with a 142 touching the lands.

my load in my 6CM was 42.9g H4350 .025 off the lands with a 115g DTAC and no where near compressed with a .109 freebore.

as far as trying my way it dont matter either way to me...if QL is working for you then by all means stick with it...it works for my buddy to but it just takes more to get to the end result IMHO....and yes he is every bit as knowledgeable with QL as you are...ill get him over here.

now if your going to actually try my way then by all means run every thing the same EXCEPT your seating depth...run it .025 off the lands regardless if you can run them in a mag or not...the only reason id say go deeper is if you do not have the bullet seated about 3/4s of the way in the neck...minimum 1/2 way.
Okay, I’ll bite.

I’m going to be open minded and try your approach using my 6.5CM. I’ll load 3 round each for as many cartridges as are needed to run from 41 grains to a full case. I’ll use new Lapua brass and the same powder, primer, and bullet as I have been using. I’ll also run a QL model and we’ll see how it compares to the field test. Will try to get this done sometime during the next few weeks. I’ll report back to you.


Hello LongRange,
Shortly after our exchange I ran a QL model for the cartridge configuration we discussed (.025" off of the lands). QL estimates 40.9 grains for 2720 fps which is the optimum velocity for Long’s Node 5 coefficient.
Today, I ran the ladder. Results are attached. Loads using 41.1 grains, 41.7 grains, and 42.3 grains all look good to me. If I correctly understand your load selection approach, you would use the 41.7 grain load. Is that right?


RPR65 Ladder 1.jpg

RPR65 Ladder 2.jpg
 

rw blakemore

Member
Forum Supporter
#88
Thank you LongRange.
Hello Gwain,
Go here get calculator. http://www.the-long-family.com/optimal barrel time.htm

You can input barrel length and node start point. To get the half node, change first node to -.5. That is a negative .5. These barrel times are what you match to OBT in QL. I can use QL and load manual to develope starting load. Typically run 3 or 4 charge weights in .3 grain increments. Once fired I have fired case H2O capacity and velocities to help true QL. Now I can find the OBT that is under max, typically the 4.5 node and then I load across that node. So if QL says 42.5 is the node I run 42.4, 42.5 and 42.6 to find the actual accuracy node the rifle likes. I can finish by running seating depth test once I have the charter weight. Hit node inside 50 rounds last time. So I kinda use the velocity ladder and QL together to build profile and find optimized load.

View attachment 38652
Hello Gwain,
QL v. ladder results are shown in #87. I'd appreciate hearing your thoughts on which load/charge to use.
 

rw blakemore

Member
Forum Supporter
#90
I think your odds are good.

QL works very well when I have some dope on powder burn rate and barrel nodes. Otherwise, it's kind of sketchy. If you have any interest in running QL for a load you are having trouble with I’d be happy to do it for you.

For the upcoming test I’ll run a 142 grain SMK/Lapua brass/H4350/RPR6.5CM-Proof Research barrel. Only recently installed the Proof barrel. Approximately 130 rounds on it. Based on tests run so far, it likes 41.4 grains, 2710 fps, .040 off lands, .4 MOA (see post # 70).

Just finished the QL model for the test. Charge will range from 41.0 to 42.8 grains (compressed load) in .2 grain steps. QL predicts three nodes, 2605 fps, 2720 fps, and 2925 fps for best precision. Will skip the low node and the high node. Low node not interesting. Can’t put enough powder in the case to reach the high node. Need to put 44.6 grains in the case (anything over 41.7 grains is a compressed load) to reach the high node and max case pressure would be 77100 psi or about 14000 psi over the SAAMI recommended limit. I expect to see 2700 fps for the 41.0 grain charge and 2815 fps for the 42.8 grain charge.
See post #87 for results.
 

LongRange

Obsessed Member
Forum Supporter
#91
Okay, I’ll bite.

I’m going to be open minded and try your approach using my 6.5CM. I’ll load 3 round each for as many cartridges as are needed to run from 41 grains to a full case. I’ll use new Lapua brass and the same powder, primer, and bullet as I have been using. I’ll also run a QL model and we’ll see how it compares to the field test. Will try to get this done sometime during the next few weeks. I’ll report back to you.

Hello LongRange,
Shortly after our exchange I ran a QL model for the cartridge configuration we discussed (.025" off of the lands). QL estimates 40.9 grains for 2720 fps which is the optimum velocity for Long’s Node 5 coefficient.
Today, I ran the ladder. Results are attached. Loads using 41.1 grains, 41.7 grains, and 42.3 grains all look good to me. If I correctly understand your load selection approach, you would use the 41.7 grain load. Is that right?


View attachment 39238

View attachment 39239
i would run the 42.3g load(for 3 reasons)and not because of the group size...1 because of the group sizes on either side of the 42.3g load are tighter...the low right shot in 42g is you not the load so see you have 3 charge weights that pretty much shoot the same so if its hotter or colder the 42.3g load will shoot...a .6g spread and it is a very stable load...2 because you have a pretty nice flat spot there...3 personally ill take a little bit looser load for a little more velocity.

so now id load 15 rounds(with a couple extra in case you have a pulled shot/called flyer)at 42.3g 5 .seated .035 off 5 at .025 off and 5 at .015 off and shoot them at 400-500yds(or close to half the distance you plan to shoot)and the best group wins.
with the way those groups look you should be somewhere in the low teens or less with your ESs when its all said and done.
 

rw blakemore

Member
Forum Supporter
#92
i would run the 42.3g load(for 3 reasons)and not because of the group size...1 because of the group sizes on either side of the 42.3g load are tighter...the low right shot in 42g is you not the load so see you have 3 charge weights that pretty much shoot the same so if its hotter or colder the 42.3g load will shoot...a .6g spread and it is a very stable load...2 because you have a pretty nice flat spot there...3 personally ill take a little bit looser load for a little more velocity.

so now id load 15 rounds(with a couple extra in case you have a pulled shot/called flyer)at 42.3g 5 .seated .035 off 5 at .025 off and 5 at .015 off and shoot them at 400-500yds(or close to half the distance you plan to shoot)and the best group wins.
with the way those groups look you should be somewhere in the low teens or less with your ESs when its all said and done.
Will do. Thanks for the guidance and support. I'll leave the brass alone, no annealing. Will report back with the results.
 

rw blakemore

Member
Forum Supporter
#94
what do you normally do to your brass after you fire it?
I anneal after firing, then full length size with Redding bushing die.

For the 42.3 grain COAL test you recommended, I want to use the Forester FLS die again and not anneal the brass. This will eliminate a couple of variables (tension and neck material hardness). Okay?
 

Gwain

New member
#96
What barrel length? Did you look at the 4.5 barrel time number? I agree with Longrange, and I would verify the obt in ql against the 4.5 node. Mine always seem to land on the half nodes. I adjust the Ba factor to show the actual velocity I am getting the find the obt that matches. I always seem to be within a tenth or two of the grain and within 5 fps when done. I change the node in the calculator to .5 this gets you the half nodes. I always look at 3.5, 4 and 4.5 nodes. Those are always the high end nodes. Find those optimal barrel times in ql and i bet it is around the 42.3 load.
 

rw blakemore

Member
Forum Supporter
#97
What barrel length? Did you look at the 4.5 barrel time number? I agree with Longrange, and I would verify the obt in ql against the 4.5 node. Mine always seem to land on the half nodes. I adjust the Ba factor to show the actual velocity I am getting the find the obt that matches. I always seem to be within a tenth or two of the grain and within 5 fps when done. I change the node in the calculator to .5 this gets you the half nodes. I always look at 3.5, 4 and 4.5 nodes. Those are always the high end nodes. Find those optimal barrel times in ql and i bet it is around the 42.3 load.
Thank you for the reply. I put together a worksheet that compares QL’s calculated BT to Long’s OBT. See attachment.
I adjusted QL’s Ba value until the QL calculated bullet velocity agreed with observed (chronograph) velocity values. Then I divided the corresponding QL BT by Long’s OBT value for the nodes of interest. The results show that something in the range of 41.4 to 41.7 grains and 42.3 to 42.9 grains produce a BT that is within 1% of Long’s Node 5 and the half node 4.5. I don’t know how to decide from this if I should develop a load that’s in the range of 41.4 to 41.7 grains or one that’s in the range of 42.3 to 42.9 grains. I’d appreciate hearing your thoughts on this.
I’m concerned about using half nodes. If we use fractional Long node values to find a match with QL’s calculated BT, why not use quarter or eighth or sixteenth nodes? Somewhere in the infinite range of fractional node values there would be an exact match to QL’s BT. Then, every load we tested would seem to be the best load if we relied solely on QL.
It’s my understanding that Long’s node values correspond to barrel times that are optimum for a given barrel length. For example, we should design to 1.102 msec, 1.228 msec, or 1.308 msec for our 24” barrel. If the bullet time to travel down the barrel does not correspond closely to one of these times, the “traveling pulse wave” moving back and forth along the barrel will not be in its optimum position when the bullet leaves the barrel. This mismatch will produce a loss of precision (large groups) even though the ES and SD values might look good.
I look forward to hearing your comments. If I’m wrong about Long’s intended use of his OBT parameters, please let me know. If you don’t have the time to “school me” no hard feelings.
Thanks again for your support. I’ve enjoyed discussing this topic with you and LongRange.


RPR65CM     QL Long half node analysis.jpg
 

Gwain

New member
#98
Not sure where you are getting the OBT from. I posted screen shots of a 24" barrel from the calculator. The 4.5 node is 1.153ms. The 5 node is 1.228 ms. You should be looking for these barrel times in QL once you have trued QL with H2O, Ba value etc. I just did a new 6cm. Fired 30 rounds for break in then a ladder from 38.5 to 40.5 grains of RL16. Trued QL, found OBT at 39.7. Best group out of ladder was 40. So I know it is close. Next I will shoot 39.5, 39.7 39.9 and see what happens. The node is there.
 

rw blakemore

Member
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#99
Not sure where you are getting the OBT from. I posted screen shots of a 24" barrel from the calculator. The 4.5 node is 1.153ms. The 5 node is 1.228 ms. You should be looking for these barrel times in QL once you have trued QL with H2O, Ba value etc. I just did a new 6cm. Fired 30 rounds for break in then a ladder from 38.5 to 40.5 grains of RL16. Trued QL, found OBT at 39.7. Best group out of ladder was 40. So I know it is close. Next I will shoot 39.5, 39.7 39.9 and see what happens. The node is there.
Half nodes are shown at the top of the page. The half node I used , 1.165, was obtained by dividing the sum of nodes 4 and 5 and then dividing by 2. The half node value obtained from the calculator is not half way between nodes 4 and 5.

I trued the QL model. For node 5 (1.228) 40.9 grains 2720 fps. For node 4.5 (1.165) 42.7 grains 2830 fps. I'll run these and let you know how they work.
 

LongRange

Obsessed Member
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no one take what im saying here wrong but once again here goes the over thinking with reloading the most over thought thing in the world...NASA puts men in space and dont think about it this much LOL!!!!

if you just like tweaking...doing load development...trying different combos then by all means continue...i personally do not....id rather be shooting out to distance gathering dopes and working on becoming a better/more consistent shooter.
ive played with QL in the past and it is a waste of MY time because it just adds another step to the reloading process and my goal has been to cut reloading times.

ive just proven that you can build an accurate load with a minimal amount of rounds and time compared to QL...if you want it slower or faster then run another load development with adjusted powder weights but the 42.3g load is money...i dont care what QL says most rifles have 3 speeds they like to shoot in and your most accurate/precise/consistent loads will be when the bullet exits the barrel at the highest point of the barrel whip.

if you are chasing loads with .1g increments in powder or seating depths of .005 increments or neck tension in .001 increments i can pretty much guarantee your load is not stable because we are talking about factory rifles with factory barrels...if we were talking about $10 and $15,000 dollar bench guns then sure they are capable of shooting those small changes....your factory rifle is not and neither are most shooters.