Load development method

[jsthntn247]

Which method would you use to work up a 1k load, 1 or 2. Will I end up at the same place using both?

1.
A. Load bullets jammed .005 and shoot a powder test to find a powder charge node using the Cortina method
B. Use best powder charge and load from 10 jam to 25 off in .003 increments to find the best seating depth.
C. At the best seating depth shoot .1 grain increments .3gr above and below the charge node
D. Shoot the best of the above with different neck tensions

2.
A. Take a random powder charge and shoot a seating depth test from 10 jam to 25 off
B. Take the best seating depth and shoot 2 ladders back to back at 1k in .2gr increments to find a powder charge
C. Shoot groups with the best of the above at 1k with different neck tensions

 

[Sniper338]

I do something more like #2. Works for me.

 

[Ned Ludd]

For an F-TR load:

1) I do charge weight optimization first with bullet seated at .015" off the lands. I typically use a variation of Erik's method, where I am looking for the minimal ES/SD window, rather than movement of the group center around a specific point of aim. Frankly, I usually don't see much, if any, of that at 100 yd. Minimal group spread is most often (although not always) associated with this window, but I use that as a secondary (not primary) indicator. Grouping will be optimized later using seating depth. Consistent velocity/resistance to velocity excursions (i.e. combustion) is the primary goal in the first step. If you can't obtain decent ES/SD numbers, meaning ES below ~12-15 fps for a .308 load with under 10 fps being optimal, or below the low 20s fps range for a .223 with the mid-upper teens being optimal, try different primers to find one that gives lower ES. You may have to redo the load development almost completely over from scratch if the velocity with the new primer(s) changes significantly, but it will be well worth it in the long run for the improved velocity numbers and vertical consistency.

2) I then do a seating depth test from .006" to .024" off the lands (Note that the initial .015" off seating depth is the center of this range, which means you're moving the bullet only half the total range in either direction during seating depth testing). Look for at least two successive increments with minimal group spread, and load to the longest.
3) Shoot a 20-25 shot string under simulated match conditions at 300-600 yd to validate load is performing as expected.

For many people, trying to do load development at 1000 yd is almost impossible. Either they do not have access to a 1000 yd range, or the typical conditions are such that it is almost impossible to properly evaluate the load performance at that distance. Try to get it close at shorter distance, where you can be reasonably certain that any change you're seeing is the effect of a load parameter, and not the wind conditions. You can tweak it as necessary if you have access to the longer range.

I do better than 90% of my load development at 100 yd, then typically validate at 300 yd. I've never had a load that shot well at 100 and 300 yd that didn't also shoot well at 1000 yd. In fact, I do not discriminate between loads based on precision at some specific distance. As long as the bullet/BC is appropriate, I'll shoot any given load/rifle at 100 yd, 300 yd, 600, or 1000 yd. It just really doesn't seem to matter when the load was developed properly. Note, I am not suggesting this is an approach for BR load development, so BR shooters please don't go into a frenzy about why this won't work for BR. It works very well for F-TR.

 

[eric32]

What type of bullet are you using? Secant ogive and tangent ogive bullet require different seating depth testing.

 

[KenOath]

Which method would you use to work up a 1k load, 1 or 2. Will I end up at the same place using both?

1.
A. Load bullets jammed .005 and shoot a powder test to find a powder charge node using the Cortina method
B. Use best powder charge and load from 10 jam to 25 off in .003 increments to find the best seating depth.
C. At the best seating depth shoot .1 grain increments .3gr above and below the charge node
D. Shoot the best of the above with different neck tensions

2.
A. Take a random powder charge and shoot a seating depth test from 10 jam to 25 off
B. Take the best seating depth and shoot 2 ladders back to back at 1k in .2gr increments to find a powder charge
C. Shoot groups with the best of the above at 1k with different neck tensions

Method #1 works for me but I do all testing at 200m, or 300m in perfect conditions. I find at the longer distance I can see more distinct differences in groups and elevation than I can at 100m.

Cheers Rushty

 

[Ned Ludd]

What type of bullet are you using? Secant ogive and tangent ogive bullet require different seating depth testing.

Not necessarily. They MAY require different different seating depths for optimal performance, but that is only a very generalized trend between secant and tangent ogive bullets, not a hard and fast rule.

As an example, I have a .223 F-TR load with the Berger 90 VLD, which is a secant ogive bullet. Some using this bullet have found they need to seat them into the lands for optimal performance, but I do not. In my hands they perform best between .015" and .018" off the lands. This is likely due to the very long and tight freebore (0.169" long, .0002" over bullet diameter). When using the Hornady OAL gauge to find "touching", it is actually necessary to push pretty hard on the plastic rod before they will even begin to move into the freebore. I believe that because of this, once the loaded round is chambered, it has nowhere else to go but straight into the bore. In this case, the sharper transition between the ogive and bearing surface of the secant ogive bullet and its effect on entering the bore is rendered less significant by the long tight freebore.

Due to the differential pressure issues associated with seating bullets well off the lands versus into the lands, I view the two scenarios as almost completely different from a load development viewpoint, because the optimal charge weight may change significantly depending on whether a bullet is seated off, or into, the lands. For that reason, I start everything at .015" off the lands. Only if I fail to find an acceptable load will I do a new and separate load development with the bullet seated into the lands. YMMV.

 

[eric32]

Your seating depth prove bergers VLD test at .010 +/-.005 Jump, in your case a little bit more was needed but it was on the ball park.

http://www.bergerbullets.com/vld-making-shoot/

This test works i have used it in the past and will continue to do so.

 

[Ned Ludd]

Actually, it doesn't prove anything like that. It simply demonstrates that secant ogive bullets don't necessarily need to be seated into the lands, which seems to be a common misconception in many places. I am fully aware of Berger's seating depth recommendations for VLDs. I did not follow that approach with this rifle, nor would I likely ever need, or choose, to use it. I'm sure it can work, but requires close attention to charge weight and pressure when moving the bullet that far in either direction. IMO, it may be very useful for factory rifles, where the freebore length is more likely require those kind of seating depth changes in order to find a "region" that actually shoots well, without having to load/test such a large number of rounds.

However, in custom F-TR rifles for which I have had specific reamers made, it is completely unnecessary. Most F-TR reloaders know exactly how their chamber has been cut, and within a fairly short window, where the bullets will need to be seated in order to optimize the load characteristics. If I can't get a specific bullet to shoot somewhere between .010" into the lands and about .024" off the lands, I'll switch to a different bullet. The Berger method moves the bullet over a total range of 0.130", in order to find a window within that range of about .040". That large of a total seating depth range largely undermines the whole reason for having a reamer made to cut a specific freebore with the idea of fully maximizing pressure and velocity for competition purposes.

The OP is a very talented F-TR shooter that I'm sure knows his exact rifle chamber specs. He will not need to test a total seating depth range of .130" to find the sweet spot, but was asking to possibly help discriminate between using one of two fairly commonly used load development approaches. In fact, given the limited options for bullets I envision he will use, I strongly suspect he will find the optimal seating depth will be between about .009" and .018" off the lands. None of the better choices available should require being seated into the lands in order to shoot well.

 

[eric32]

I see your point, i believe we are pretty much getting at the same outcome.

 

[bsbxl]

Actually, it doesn't prove anything like that. It simply demonstrates that secant ogive bullets don't necessarily need to be seated into the lands, which seems to be a common misconception in many places. I am fully aware of Berger's seating depth recommendations for VLDs. I did not follow that approach with this rifle, nor would I likely ever need, or choose, to use it. I'm sure it can work, but requires close attention to charge weight and pressure when moving the bullet that far in either direction. IMO, it may be very useful for factory rifles, where the freebore length is more likely require those kind of seating depth changes in order to find a "region" that actually shoots well, without having to load/test such a large number of rounds.

However, in custom F-TR rifles for which I have had specific reamers made, it is completely unnecessary. Most F-TR reloaders know exactly how their chamber has been cut, and within a fairly short window, where the bullets will need to be seated in order to optimize the load characteristics. If I can't get a specific bullet to shoot somewhere between .010" into the lands and about .024" off the lands, I'll switch to a different bullet. The Berger method moves the bullet over a total range of 0.130", in order to find a window within that range of about .040". That large of a total seating depth range largely undermines the whole reason for having a reamer made to cut a specific freebore with the idea of fully maximizing pressure and velocity for competition purposes.

The OP is a very talented F-TR shooter that I'm sure knows his exact rifle chamber specs. He will not need to test a total seating depth range of .130" to find the sweet spot, but was asking to possibly help discriminate between using one of two fairly commonly used load development approaches. In fact, given the limited options for bullets I envision he will use, I strongly suspect he will find the optimal seating depth will be between about .009" and .018" off the lands. None of the better choices available should require being seated into the lands in order to shoot well.

Interesting clarification concerning the different requirements for custom (F-TR) rifles and factory rifles!

I am developing a new load for my (factory) Tikka T-3 in .308W (S&B primer, Lapua Case, 155gr Scenar bullet and Reload-Swiss RS-52 powder). Taken into account the above mentioned differences between a custom and a factory rifle, what would be the best procedure? I suppose the procedure used by gstaylorg for his custom F-TR rifle, or the variation described by Cortina (in another thread), would not be optimal to develop a load for a factory rifle with a chamber dimensioned to safely handle a wide variety of bullet weights and shapes. Would one of the following two procedures (or another one) be more suitable?

1) First use the Berger procedure with a safe load to get a general idea of optimal seating depth. Then do a charge weight optimisation at the found seating depth. And finally fine tune the seating depth using the optimised charge weight.

2) Being more prudent by staying closer to the COAL given by load guides, e.g. 2.795" (Vihtavuori guide for .308W and 155gr Scenar). First determine optimal charge weight at 2.795" +0.010" followed by a seating depth optimisation in a COAL range from 2.795" - 2.815" (or till max magazine length?). This would also ensure there will be enough bullet bearing surface in the case neck.

 

[Ned Ludd]

I think you misinterpreted what I was stating. For someone with a custom rifle for which they have the chamber specs (reamer print), it is typically not necessary to test seating depths that cover an extremely wide range (i.e. > .120").

On the other hand, with a factory rifle the owner may or may not have reliable chamber specs and may have to go "fishing" in terms of seating depth to empirically determine where the rifle shoots optimally. Given the wide range of chamber specs possible in factory rifles, that may require covering a much wider seating depth range than for a chamber with known dimensions. Berger's test for quickly identifying a more narrower seating depth range when using VLD bullets is just such a test. You cover a wide range with a few seating depths initially to narrow down the range, then go back and cover a region only within that range in much finer increments. The limits for such an approach when loading to mag length can be that to cover the wider range may require going longer than mag length, or seating the bullet fairly deep in the case. In such cases, the limits are obviously set by the physical constraints imposed by the specific rifle setup.

Regardless of whether a rifle is factory or custom, if you can seat a bullet at "touching" the lands and still have sufficient minimal bearing surface in the neck, you should be good to go with regard to a normal seating depth test range. If you cannot seat a bullet at "touching" without it falling out of the neck OR exceeding mag length, then you have to determine the working seating depth range you can realistically cover, and take it from there. Some factory rifles can have exceedingly long free bores; long enough that some bullets cannot be seated out to "touching, or into the lands, and still have sufficient bearing surface remaining in the neck. The more you know about your chamber specs, the less work it is likely to be in terms of testing and optimizing seating depth.

In your example above, the very first thing I would is determine whether you can realistically seat a bullet out to "touching". If so, how much shank is left in the neck? If there is sufficient shank engagement in the neck AND you are within mag length requirements (if necessary), I would simply start your charge weight testing with the bullet seated at .015" off the lands. Once you find your optimal charge weight, test seating depth in .003" increments to either side (i.e from about .003" or .006" off to about .021" or .024" off). I have yet to find a load that hasn't grouped well somewhere within that range. If you cannot seat out to "touching", then you may want to use the book COAL values and anticipate that you may need to cover a wider range during seating depth testing, while remaining within mag length requirements, if necessary.

There are a number of different ways to accomplish this goal. I am a simply fan of using whatever information I have available, or can determine on my own, to make the process as easy as possible.

 

[bsbxl]

Gstaylorg, thanks for your reply.

Per the method described by Cortina, I made a dummy round to get an idea of were the lands are (CBTO to jam). This dummy round has a COAL of 2.905". Given the bullet measurements in Litz's book, I estimate the bullet bearing surface in a standard COAL of 2.795" to be about .300" (about a calibre). At 2.905" this would be 0.110" less bullet bearing surface in the case neck: 0.190", still more than half a calibre (if my numbers are right). Would that be sufficient to work from?

I already did a first powder charge test at 0.020" from jam with loads from 44gr to 46gr in 0.5gr steps. Vertical spread from the 44.5gr and 45.0gr loads was very close. Tomorrow I will do some fine tuning with loads from 44.6gr to 45.4gr in 0.2gr steps.

When I have settled on a powder charge weight, I will test for optimal seating depth. Would a test with seating depths at 0.015" to 0.029" (in 0.003" steps) from jam be a good idea? Estimated bullet bearing surface in this test would vary from 0.202" to 0.219".

Gstaylorg, in your method you use velocity ES/SD to determine the best charge weight. How many shots do shoot per weight and what weight steps do you use?

 

[StevenDzupin]

Which method would you use to work up a 1k load, 1 or 2. Will I end up at the same place using both?

1.
A. Load bullets jammed .005 and shoot a powder test to find a powder charge node using the Cortina method
B. Use best powder charge and load from 10 jam to 25 off in .003 increments to find the best seating depth.
C. At the best seating depth shoot .1 grain increments .3gr above and below the charge node
D. Shoot the best of the above with different neck tensions

2.
A. Take a random powder charge and shoot a seating depth test from 10 jam to 25 off
B. Take the best seating depth and shoot 2 ladders back to back at 1k in .2gr increments to find a powder charge
C. Shoot groups with the best of the above at 1k with different neck tensions

What ever you try,change only one thing at a time and keep accurate notes.
Prevents a lot of frustration and wasted components.

Regards,

Steve

 

[Ned Ludd]

I prefer to keep the boattail/bearing surface junction somewhere between just above the neck/shoulder junction, and about halfway up the neck. If you're concerned there may not be enough shank in the neck, your numbers sound ok, but you can always give a dummy round the old finger twist test. With about .002 neck tension, you should not be able to move the bullet easily with just your fingers trying to twist/pull it out.

I usually do fine increment testing in 0.1 gr increments for both .223 and .308, using 5-shot groups for everything. I use a MagnetoSpeed chronograph, which attaches to the barrel and can alter barrel harmonics. For that reason, I load 10 rounds at each charge weight, shooting 5 shots for MV with the MagnetoSpeed attached, and 5 shots with it off for grouping. You want to cover your potential accuracy window such that you can define the boundaries on either side and load to the middle.

About the only place I ever do "jam" is on toast. Regarding seating depth, I don't do "jam" unless it's absolutely necessary, and perhaps not even then. FWIW - "off" is out of the lands, "touching" has the ogive just barely touching the lands, "into" the lands can be anywhere from .001" in to as much as .025 or so in. In many cases, a "hard jam" may require seating the bullet from about .015" to about .025" into the lands. Something like .010" into the lands does not usually constitute a "hard" jam. My recollection is that Erik's method may index from hard jam, but I may be wrong about that. I would suggest not mixing and matching different people's variations on these approaches. Erik's approach works very well and if you have started out using that, particularly with regard to seating depth, I would continue that to conclusion. I view "jam" and "off" as almost two completely different load developments, like if I were switching lots of powder or using a new bullet. That is one reason I try to keep bullets out of the lands of possible. The typical bullets I shoot do not require seating into the lands, so I do the charge weight testing at .015" off, then seating depth over a range of about .003"-.006" off to .021"-.024" off. Note that .015" is in the center of that range, meaning you're only moving the bullet half the total seating depth range in either direction. This minimizes velocity excursions due to moving the bullet far enough in/out during seating depth testing to significantly affect pressure. Most all of the bullets I have used tuned in somewhere between about .009" and .018" off the lands.

 

[bsbxl]

Gstaylorg, thanks again for your reply.

My dummy round passed the finger twist test so that should be ok.

The "jam"-vocabulary comes indeed from Erik Cortina. I used his method to create a dummy round to make the relative measurements from for seating depth. His method prescribes closing the bolt on a long seated dummy round. I did it with three rounds and the results were very consistent. I also have the Hornady tool but I could not get consistent results with it, too much variation. Perhaps I should practice more with it.

I would certainly prefer to stay off the lands also. If "jam" is already .015"-.025" into the lands, I should probably do my seating depth testing from .020" -.040" from jam, just to be sure of staying away from the lands.

I like the idea of using both velocity (ES/SD) and groups to determine the best charge weight, although it augments the round count of the test. I will probably implement this in my next load development cycle.

Gstaylorg, one last question: the fine increment testing in 0.1gr increments, is that after you have determined a promising charge weight zone in a previous coarser test? Or do you start your test with 0.1gr increments? I started with a coarse test over 2 full grains of powder in 0.5gr increments. In a second session I do a test with 0.2gr increments over a 1 grain spread in the most promising zone from the first test.

 

[Ned Ludd]

Without opening a whole new can of worms, I use a reloading program, Quickload. After initial calibration of the program to a particular rifle load using a known charge weight, QL allows me to go directly to fine increment charge weight testing (0.1 gr). So I rarely need to do coarse charge weight testing. Obviously there is a lot more to the story than just that, but I'd rather not go off on that tangent in this thread. As long as your charge weight test covers both the lower/upper boundaries of the window, you should be able to define the center, regardless of what increment charge weight you used to cover the window region, unless it was unreasonably large for a given cartridge. The 0.1 to 0.2 gr range should be fine most work.

Even though I start directly in at the fine increment level, I still have to load enough increments to cover the window, and I still have to shoot the loaded rounds for MVs and groups. The larger the case, the larger the charge weight increment can be and still give satisfactory results. In my .223s, I would not be satisfied with 0.2 gr or larger increments, the case is simply too small and you might actually miss something. In the .308, I also use 0.1 gr increments, but it may be overkill as I mentioned.

It seems as though you have already gotten well along with Erik's method, so my best advice at this point is to continue with it exactly as he has outlined. I think you will be very happy with the results and you gain a better feel for the total process. If you have questions about variations or alternative reloading approaches at that point, ping me and I'll be happy to talk more about it. I just really don't want to distract you too much from your chosen approach at this point, because I know it works well. As I mentioned before, mixing and matching things from different approaches, even if they're pretty close, is much more of an experimental issue. That's fine when you plan to do it to specifically try out some new procedural modification, but the first time through it's better to follow the established protocol religiously.

As far as the Hornady OAL gauge, it can be tricky with some bullets and/or chambers, but with a little practice it shouldn't be too difficult to develop a good feel for when the bullet just barely "touches" the lands. I'd recommend practicing with a single bullet until you can get reproducible measurements (i.e. within ~.001" or so variance for several measurements). Then try it with several different bullets and see how it works. I typically pick 10 bullets at random from a new lot, number them with a Sharpie and measure using the Hornady OAL gauge with all 10. The average +/- SD from all ten measurements is the figure I use for "touching" on subsequent load development. I label and set those 10 bullets aside as the "measurement set" I will use for measurements with that specific rifle over the useful life of that particular lot of bullets, mainly to measure land erosion.

 

[jsthntn247]

I shot back to back ladders at 800 today. The largest node duplicated and was easy to see as 43.6 - 44 had lesss than 1" of vertical on both. However this was not the charge range I picked at 100 to test seating depth and fine tune powder with. I went back and looked at the initial charge test at 100 and I had misread it. Seems I went with the bug hole group instead of the range with no poi shifting. When the largest group at 100 is .5" it is easy to misread one.

 

[Ned Ludd]

Sounds like 43.8 gr is likely to be the spot. Is that Varget? H4895? Any idea yet of the velocity you're getting in that charge weight range? Anyhow, sounds like you're on to the loading you want. That's always a good beginning.

 

[jsthntn247]

Varget. my shoot through chrony varies so much in different light its' not even worth trying. I do have a magneto speed but don't want it to influence load dev. I have a feeling it's going to be slower than what everybody else is shooting them.

 

[fredo]

I do my own personalized/streamlined version of method #1 for load development.

1. Use QL to determine a likely powder & charge range for a chosen bullet.
2. Determine OAL to hard jam & back off .005" (still touching)
3. Load a ladder. One round at each charge weight, up to just beyond QL estimated pressure threshold.
4. 0.3gr steps for smaller cases, 0.5gr for larger cases
5. QL will help narrow down the 10-12 rds you'll want to use
6. Shoot ladder @ 300yds, use the a single POA
7. Use a chrono (if possible)
8. After firing each round, take note of any perceived heavy bolt lift along the way (pressure indicator)
9. Inspect every fired case for ejector swipe/ primer condition (pressure indicator)
10. Determine potential nodes, via vertical group dispersion.
11. If using chrono, make note of velocity gains, or lack thereof.
12. The leveling off of velocity gains can be a third indicator of over-pressure situation...

That's it.
In ~10 rounds, you've pretty much narrowed down the following:

1. a maximum charge weight to abide (from pressure indicators)
2. a good indication of powder performance, (from the chrono)
3. what potential node(s) to test, further (from the target)

Rinse & repeat the above, with different powder(s) and/or different bullet(s).

Once a potential node is ID'ed, I back off seating depth .010" from initial (touching OAL). IMHO, backing off .003 at a time is too laborious. If you're gonna jam a bullet, jam it! If you want to jump it, then jump it! Work back in .005-.010" depths from there, as necessary and depending on how anal you want to be...

Focus on testing those charge weights by shooting groups in/around that node. 3-5rds, your choice. Whatever gives you a good idea of accuracy potential.

If sizing a bushing FL die (I do), start with bushing -.002" of loaded rd. for smaller case & -.003" of loaded rd. for larger cases. No reason why, that's just what I start with...

Depending on #/shots per group, you could realistically find a very nice load with only another 12-15 rounds fired! Once best group is determined, load a bunch more and let 'em rip!

If subsequent shooting sessions determine a need for further improvement to meet your accuracy standards, keep tweaking til your heart's content. Play with seating depth again, different bushings, annealing, etc. However far you wish to test is only limited by your will & desire to do so...



Some reloaders take much pleasure in the 'tinkering' aspect of reloading, and are always testing, testing, testing. I prefer to cut to the chase, find a good load, make a bunch of em, then shoot!
When using the above method, I can get real close to finding happiness (for me) in well under 50 rounds, per powder/bullet combo. That is soup---->nuts, from knowing zilch, to having a pretty dang good load. With a well built rifle, load development just should be any harder than that!

Obviously, this might not be the recipe for success if you're a competition shooter seeking to tweak the ultimate load. But I'm not so, the above is just another couple pennies to ponder...

Good shooting!