OBT + QuickLoad experiences?

[AD5GB]

Ok, so I've been learning more and more about the software and OBT theory and kinda-sorta how to put the two together. Wondering who's done this before me and what those experiences might be. Naturally, I'm most grateful for any tips!

What I've done/learned thus far:

QuickLoad and real world results can differ - markedly. This didn't surprise me. I understand the variables involved. I've carefully measured things like case capacity, real barrel length, seating depth to lands for several bullets and have taken existing load and chrono data and by fudging the Ba (burn rate factor) have gotten QL velocities to line up with actual measured velocities. Next, I've adjusted powder charges to give me an actual barrel time for the load that aligns with the highest usable barrel node (spreadsheet calculation from a couple different sources). My first trip to the range last weekend produced velocities still higher than anticipated and thus above the targeted barrel node. Groups were just OK, .8" or so. I'm going to repeat the exercise again this weekend based on more adjustments from this exercise.

What I'm wondering:
1: What people might have found as a barrel time "window", meaning, how wide (+-) is the node in terms of mS related to the target time?

2: Are these burn rate factor adjustments portable to other bullets one might use in the same rifle? Meaning, can the adjustment used for H-1000 with a 212gr ELD-X be applied to a 190gr SMK in the same rifle? (assuming same powder canister of course)

3: Any experiences with using QL + OBT theory with powders not listed in the software. I'd like to apply this to IMR-7977. My .270 loves this stuff. It's really unfussy though, unlike my 300 winnie which seems quite finicky.

Much TIA for your thoughts!

 

[Mikecr]

I think you should not attempt to use OBT theories in lieu of load development.
This, because I've yet to see OBT as predictive to best loads. Instead it always seems hindsight correlations (often stretched to). Right? You're trying to correlate in hindsight.

It is no where near possible today to predict best load per barrel & bullet & powder lot, & primer lot, & case capacity.

 

[benchracer]

Ok, so I've been learning more and more about the software and OBT theory and kinda-sorta how to put the two together. Wondering who's done this before me and what those experiences might be. Naturally, I'm most grateful for any tips!

What I've done/learned thus far:

QuickLoad and real world results can differ - markedly. This didn't surprise me. I understand the variables involved. I've carefully measured things like case capacity, real barrel length, seating depth to lands for several bullets and have taken existing load and chrono data and by fudging the Ba (burn rate factor) have gotten QL velocities to line up with actual measured velocities. Next, I've adjusted powder charges to give me an actual barrel time for the load that aligns with the highest usable barrel node (spreadsheet calculation from a couple different sources). My first trip to the range last weekend produced velocities still higher than anticipated and thus above the targeted barrel node. Groups were just OK, .8" or so. I'm going to repeat the exercise again this weekend based on more adjustments from this exercise.

What I'm wondering:
1: What people might have found as a barrel time "window", meaning, how wide (+-) is the node in terms of mS related to the target time?

2: Are these burn rate factor adjustments portable to other bullets one might use in the same rifle? Meaning, can the adjustment used for H-1000 with a 212gr ELD-X be applied to a 190gr SMK in the same rifle? (assuming same powder canister of course)

3: Any experiences with using QL + OBT theory with powders not listed in the software. I'd like to apply this to IMR-7977. My .270 loves this stuff. It's really unfussy though, unlike my 300 winnie which seems quite finicky.

Much TIA for your thoughts!

I have done a lot of load work using OBT, along with QL and a good chronograph, during the past couple of years. I have found it to work very well.

The OBT/QL method does not replace load development, but it can make the process more efficient. I have also found it to be very helpful in developing stable long range loads.

OBT theory states that the window for a given node is typically +/- .020 ms. I have observed this to roughly translate to a velocity window that is about 60 fps wide, though the size of the window may sometimes be larger or smaller.

I don't personally adjust the burn rate factor. I believe the OBT method works best when seating depth testing is done first. I perform the Berger seating depth test with a starting load, using the velocity data from that test to reconcile actual results with QL predicted results. My experience has been that predicted velocities for nodes and max tend to be accurate, though the powder charge required to get there tends to differ between predicted and actual.

One of the biggest mistakes I see people make, when using QL, is the tendency to treat predicted powder charges as gospel. Doing that is a VERY BAD IDEA! Powder charges are heavily dependent on burn rate, which is probably the least static variable in the entire equation.

In the summer and fall of 2015, I experimented heavily with the OBT method of load development, trying to determine its limitations and how best to integrate it into my personal load development process. It was interesting to watch the ES and SD numbers narrow as the predicted node was approached and widen on the other side of the node. I successfully developed several long range loads by shooting them over a chrono, at short range into a backstop, tuning them solely with velocity data, before shooting them for groups at ranges varying from 100 to 500 yards.

I haven't personally attempted the OBT method with a powder not supported by QL. In such cases, I use the Newberry OCW method, which has consistently yielded good results for me. I used the OCW method before I owned a chronograph, though it could easily be paired with a chronograph for more refined results.

The OBT method gets me there with fewer rounds fired and is more versatile/flexible, though there is strong correlation between the two methods. Essentially, the OBT method gives you a velocity target and allows you to narrow the range of powder charges for testing. Being able to predict the velocity range(s) where the node(s) will fall is useful in selecting components and allows for greater adaptability with respect to available facilities during load development.

 

[AD5GB]

The OBT/QL method does not replace load development, but it can make the process more efficient. I have also found it to be very helpful in developing stable long range loads.

Thanks for the detailed response. To clarify my intent was definitely *NOT* to replace intelligent load development techniques - it's what I've tried to do for some 35 years. The intent is to, as you said, streamline the process as well as hopefully further refine what I already do know.

I don't personally adjust the burn rate factor. I believe the OBT method works best when seating depth testing is done first. I perform the Berger seating depth test with a starting load, using the velocity data from that test to reconcile actual results with QL predicted results. My experience has been that predicted velocities for nodes and max tend to be accurate, though the powder charge required to get there tends to differ between predicted and actual.

Excellent! I've done the Berger test with a couple bullets as you describe and have observed the differences between predicted and actual powder charges as well. To be sure I understand you, the goal then would be to achieve the QL velocity at the previously determined 'best' seating depth that corresponds with the barrel time you desire to achieve? This has been my thinking anyway. What I've found interesting with this is that different powders produce different MV numbers for a given barrel time. As much as 120fps difference between RL26 and IMR4831 in a 300WM 190gr SMK model for example. I get it, different powder characteristics, different acceleration rates etc. I was just intrigued. I've also observed differences in the predicted MV when changing seating depths and adjusting the powder charge (again within QL) to obtain the desired barrel time. Again, intriguing observation.

One of the biggest mistakes I see people make, when using QL, is the tendency to treat predicted powder charges as gospel. Doing that is a VERY BAD IDEA! Powder charges are heavily dependent on burn rate, which is probably the least static variable in the entire equation.

This I understood. I started with the QL/OBT experiments already armed with known charge/velocity data on hand from previous range sessions based on starting load information from loading manuals. I felt quite safe with what I'd come up with.

In the summer and fall of 2015, I experimented heavily with the OBT method of load development, trying to determine its limitations and how best to integrate it into my personal load development process. It was interesting to watch the ES and SD numbers narrow as the predicted node was approached and widen on the other side of the node. I successfully developed several long range loads by shooting them over a chrono, at short range into a backstop, tuning them solely with velocity data, before shooting them for groups at ranges varying from 100 to 500 yards.

Again excellent. I think I saw this with one of my tests actually. The load I came up with in QL was about 70fps faster than what it QL said I should have for the optimum barrel time. 190SMK, 71.1gr IMR7828. Predicted was 2916fps, actual was 2982av. ES 12 SD 8.08. Group size was disappointing but I intend to revisit this load with further changes in seating depth at this charge/velocity level.

Thanks again for taking the time with the details. Sounds like you've achieved what I set out hoping to. OBT theory and QuickLoad are both new to me.

As an aside I probably wouldn't be here at all if this particular rifle project had been as trouble free as my others. That said the experience and education will undoubtedly be valuable. Either I'll end up with another shooter or burn the barrel trying - LOL

 

[benchracer]

To be sure I understand you, the goal then would be to achieve the QL velocity at the previously determined 'best' seating depth that corresponds with the barrel time you desire to achieve?

Correct. When working with QL, I find it beneficial to provide the most accurate and complete data possible. Establishing preferred seating depth first gives you more accurate case capacity, which improves the quality of the data you will generate in QL. Moreover, I have found preferred seating depth to be bullet dependent, which allows you to try different powders without needing to re-test seating depth.

From there, it is a matter of tuning to the correct velocity range. I like to work past the OBT predicted node to establish the node center and the upper and lower bounds of the node. Providing you can achieve tight enough ES and SD spreads, choosing a powder charge near the center of the node can allow you to build some tolerance into your load for changing conditions.

This has been my thinking anyway. What I've found interesting with this is that different powders produce different MV numbers for a given barrel time. As much as 120fps difference between RL26 and IMR4831 in a 300WM 190gr SMK model for example. I get it, different powder characteristics, different acceleration rates etc. I was just intrigued. I've also observed differences in the predicted MV when changing seating depths and adjusting the powder charge (again within QL) to obtain the desired barrel time. Again, intriguing observation.

This plays heavily into my choice of components. I often look for a bullet/powder combination that yields a high node that is fairly close to max, thus ensuring that I am efficiently using the available case capacity.

This I understood. I started with the QL/OBT experiments already armed with known charge/velocity data on hand from previous range sessions based on starting load information from loading manuals. I felt quite safe with what I'd come up with.

That's generally how I try to do things, as well. I try to cross-check and sanity check things as much as possible.

Again excellent. I think I saw this with one of my tests actually. The load I came up with in QL was about 70fps faster than what it QL said I should have for the optimum barrel time. 190SMK, 71.1gr IMR7828. Predicted was 2916fps, actual was 2982av. ES 12 SD 8.08. Group size was disappointing but I intend to revisit this load with further changes in seating depth at this charge/velocity level.

You have pretty good ES and SD numbers with that load. It will be interesting to see if they tighten as you drop into the node. The top of the node should appear around 2950ish.

Thanks again for taking the time with the details. Sounds like you've achieved what I set out hoping to. OBT theory and QuickLoad are both new to me.

I am always glad to help wherever I can. I still consider myself to be pretty new at OBT and QL. It's nice to have some tools that help one to better understand how some of the puzzle pieces fit together.

 

[MarkA]

I have done a lot of load work using OBT, along with QL and a good chronograph, during the past couple of years. I have found it to work very well.

The OBT/QL method does not replace load development, but it can make the process more efficient. I have also found it to be very helpful in developing stable long range loads.

OBT theory states that the window for a given node is typically +/- .020 ms. I have observed this to roughly translate to a velocity window that is about 60 fps wide, though the size of the window may sometimes be larger or smaller.

I don't personally adjust the burn rate factor. I believe the OBT method works best when seating depth testing is done first. I perform the Berger seating depth test with a starting load, using the velocity data from that test to reconcile actual results with QL predicted results. My experience has been that predicted velocities for nodes and max tend to be accurate, though the powder charge required to get there tends to differ between predicted and actual.

One of the biggest mistakes I see people make, when using QL, is the tendency to treat predicted powder charges as gospel. Doing that is a VERY BAD IDEA! Powder charges are heavily dependent on burn rate, which is probably the least static variable in the entire equation.

In the summer and fall of 2015, I experimented heavily with the OBT method of load development, trying to determine its limitations and how best to integrate it into my personal load development process. It was interesting to watch the ES and SD numbers narrow as the predicted node was approached and widen on the other side of the node. I successfully developed several long range loads by shooting them over a chrono, at short range into a backstop, tuning them solely with velocity data, before shooting them for groups at ranges varying from 100 to 500 yards.

I haven't personally attempted the OBT method with a powder not supported by QL. In such cases, I use the Newberry OCW method, which has consistently yielded good results for me. I used the OCW method before I owned a chronograph, though it could easily be paired with a chronograph for more refined results.

The OBT method gets me there with fewer rounds fired and is more versatile/flexible, though there is strong correlation between the two methods. Essentially, the OBT method gives you a velocity target and allows you to narrow the range of powder charges for testing. Being able to predict the velocity range(s) where the node(s) will fall is useful in selecting components and allows for greater adaptability with respect to available facilities during load development.

+1! I use the methods above nearly to a tee. IMO shortens path to final load.

 

[Clark]

Google says OBT means Olympic Ballet Theatre.

I have been using Quickload since 1999, and I have not seen OBT on the screen.

 

[AD5GB]

Google says OBT means Olympic Ballet Theatre.

I have been using Quickload since 1999, and I have not seen OBT on the screen.

LMAO! Now that would be pretty remarkable.

 

[AD5GB]

Well, lookee there. There might be something to that thar OBT theory after all!

Group 1 was where I'd left off. It shot 2988 avg today. 2 and 3 were 2730 and 2743 averages. 4 came out to 2928 av. All had single digit SD numbers though. I guess I'll step over to the 500yd range next and stretch its legs a bit.

I'm encouraged that this thing might have some potential after all....

Thanks much all!