Question on OBT

[MrBottleneck]

I was studying and learning more about the theories of OBT using in conjuction with QL.

I found this chart Steve Blair (thanks Steve) created.
http://forum.accurateshooter.com/threads/obt-chart-for-quickload-users.3796920/

So read Chris Longs (thanks Chris) papers here:
http://www.the-long-family.com/OBT_paper.htm

Talk about some good reading and awesome graphs.

My question is how many guys when they purchase a new BA Rifle with a certain barrel length actually turn to OBT to help them start in load development in conjunction with QL?
It seems like a great place to get good start considering it appears node testing seems to equate perfectly with OBT of a certain barrel length.

What you all say?

 

[Capt. Oblivious]

Ill turn to QL and OBT for a theoretical "load" before I decide on a caliber and barrel length with the bullet I plan on shooting. Now I can see what node I can achieve with barrel length X and what % fill rate I can be looking at with powders y and z, unfortunately we don't have the big selection of powders you guys have so its "harder" to get everything I want and QL/OBT helps allot in making the initial decisions

 

[savagedasher]

I was studying and learning more about the theories of OBT using in conjuction with QL.

I found this chart Steve Blair (thanks Steve) created.
http://forum.accurateshooter.com/threads/obt-chart-for-quickload-users.3796920/

So read Chris Longs (thanks Chris) papers here:
http://www.the-long-family.com/OBT_paper.htm

Talk about some good reading and awesome graphs.

My question is how many guys when they purchase a new BA Rifle with a certain barrel length actually turn to OBT to help them start in load development in conjunction with QL?
It seems like a great place to get good start considering it appears node testing seems to equate perfectly with OBT of a certain barrel length.

What you all say?

Bullet speed changes so much with twist and lands difference that with lot difference in powder and seating depth .
Not worth the effort to me. I don't use bullet drop charts Also . Bullet impact still works.
If chasing your tail is your thing go for it.
Larry

 

[linedrive301ft]

I use QL and OBT when looking for a new load. Saves on components and testing.
It has worked very well for me.

 

[Nomad47]

I also use QL and OBT. I've had the pleasure of a few short discussions with Chris Long. He is one smart individual.

 

[RonAKA]

I will be frank. I don't believe the computerized methods of predicting "nodes" is accurate enough or even based on valid theory. The good old fashioned Ladder Test is what I find works in practice and is based on sound theory.

 

[BCBRAD]

I use QL and OBT to get OCW.

A valuable tool in search of an accurate load.

An example is , I want to use my hunting rifle for a hunter class at a local club 1000 yard shoot, (many use specialized rigs that comply with the rules) I wanted to use my actual hunting rifle, it is a 30-06 Finnlight with a 6X Leupold and M1 turret thats been banged around in the bush and on the bars of a quad for years.
I also want to hold on the cross hairs, so I search for a bullet that has a high BC that I can drive fast enough to do this. 155.5 Berger Fullbore has the BC and I can drive it at ~2950 ft/s, so it needs 31 moa up to do this , the M1 has ~35 moa so I'm in.

Modeling a load QL tells me H-4350 is the powder, OBT gives me a node I can reach with 61 grains. Load looks promising at 100 yards.

At 1048 yards it printed a 0.7 moa 3 shot group and a 1.6moa 5 shot group.

No ladder test , no extensive fiddling, the limitations are the shooter, a 6X scope and a well worn rifle.

 

[Jeff A]

I always start with QuickLOAD and OBT. It saves me money in components and wear and tear on equipment.

 

[jlow]

I was studying and learning more about the theories of OBT using in conjuction with QL.

I found this chart Steve Blair (thanks Steve) created.
http://forum.accurateshooter.com/threads/obt-chart-for-quickload-users.3796920/

So read Chris Longs (thanks Chris) papers here:
http://www.the-long-family.com/OBT_paper.htm

Talk about some good reading and awesome graphs.

My question is how many guys when they purchase a new BA Rifle with a certain barrel length actually turn to OBT to help them start in load development in conjunction with QL?
It seems like a great place to get good start considering it appears node testing seems to equate perfectly with OBT of a certain barrel length.

What you all say?

The rifle’s specific quirks does affect its accuracy node, this is why when you have a new rifle/barrel, the first thing you do is to shoot what I call a pressure test – basically single round going from low to high, capturing MV and looking for pressure. With that information, you will be able to adjust QL so that it give you accuracy information, specifically where the accuracy nodes approximately are. Knowing that, you can then run an abbreviated OCW around the predicted node to find where the node actually is. You still need to sharpen things up with seating depth test and so forth but you are never left fumbling around looking for the accuracy node without an idea of where it is. Both a Ladder Test and OCW allows you to do this to certain extend but this just makes it even easier using one of those methods.

It's like having a guy whisper clues (although not necessarily the absolute answer) to you to help you get there faster - who would not love to have that?

 

[savagedasher]

If you pick a powder that the Z1 and Pmax Are one Line on or before the pressure the pressure curve it will always shoot . Larry

 

[MrBottleneck]

I appreciate everyones input. I was just fascinated by what seems like just another great starting point in load development. Using it with ladder tests or others in conjuction seem like they would give even more definitive nodes. Im all in on on learning new ways to help quickly pinpoint nodes especially when a new rifle I am not attune too is purchased.

Larry, I am not an expert on QL so, can you please eloborate on what you saying. The curve changes for every input of say charge weight etc. so, you kind of have lost me.
Any chance you could show a graph helping explain. Maybe an upload of a QL graph on what you personally look for then I can compare it to some I have run using the same graph. Have you found by your methods when you say "it will always shoot" does it correspond in any way to the nodes OBT show?

 

[savagedasher]

I appreciate everyones input. I was just fascinated by what seems like just another great starting point in load development. Using it with ladder tests or others in conjuction seem like they would give even more definitive nodes. Im all in on on learning new ways to help quickly pinpoint nodes especially when a new rifle I am not attune too is purchased.

Larry, I am not an expert on QL so, can you please eloborate on what you saying. The curve changes for every input of say charge weight etc. so, you kind of have lost me.
Any chance you could show a graph helping explain. Maybe an upload of a QL graph on what you personally look for then I can compare it to some I have run using the same graph. Have you found by your methods when you say "it will always shoot" does it correspond in any way to the nodes OBT show?

Pm sent. Larry

 

[Twoboxer]

Calibrating QL for my powder batch etc has been difficult for me. Getting QL to produce data where the MVs match the real world performance of 2 or more different charges has proven impossible for me. So how accurate/useful are its "predictions"?

What it can do - and has done for me - is give me an idea that a particular load might be tunable to a given node . . . and that may prove to end up being anything from meaningful to meaningless lol.

Sorry - just my experience.

 

[savagedasher]

Calibrating QL for my powder batch etc has been difficult for me. Getting QL to produce data where the MVs match the real world performance of 2 or more different charges has proven impossible for me. So how accurate/useful are its "predictions"?

What it can do - and has done for me - is give me an idea that a particular load might be tunable to a given node . . . and that may prove to end up being anything from meaningful to meaningless lol.

My H4350 was dead on. Varget was off 70' per second just from lot to lot. Larry

 

[savagedasher]

Calibrating QL for my powder batch etc has been difficult for me. Getting QL to produce data where the MVs match the real world performance of 2 or more different charges has proven impossible for me. So how accurate/useful are its "predictions"?

What it can do - and has done for me - is give me an idea that a particular load might be tunable to a given node . . . and that may prove to end up being anything from meaningful to meaningless lol.

My H4350 was dead on. Varget was off 70' per second just from lot to lot. Larry

 

[Twoboxer]

My H4350 was dead on. Varget was off 70' per second just from lot to lot. Larry

To be clear, I can "tune" it to match almost any ONE MV, but not multiple charges leaving all else the same . . . eg, 45gr, 47.5gr, and 50.0gr using same bullet/brass/primer and physical parameters.

 

[savagedasher]

To be clear, I can "tune" it to match almost any ONE MV, but not multiple charges leaving all else the same . . . eg, 45gr, 47.5gr, and 50.0gr using same bullet/brass/primer and physical parameters.

Every time you change powder the fps can be off so you must check each powder to adjust it accordingly. . That is the reason I don't use OBT. The speed calculation at base off the powder manufactured burn rate .
Larry

 

[Nomad47]

I also use QL and OBT. I've had the pleasure of a few short discussions with Chris Long. He is one smart individual.

I would love to listen in on a conversation between Chris Long and Bryan Litz, although I probably wouldn't understand 90% of the conversation.

 

[/VH]

I would love to listen in on a conversation between Chris Long and Bryan Litz, although I probably wouldn't understand 90% of the conversation.

Nomad,

Sometimes I have that same 90% problem just reading these threads.

 

[Nomad47]

Nomad,

Sometimes I have that same 90% problem just reading these threads.

LOL. I gotta agree with that.