The chicken or the egg... powder load or jump, which first?

[thefitter]

How do you go about starting to develop a load for a completely new caliber? My tendency when starting something completely new is to read up on what others are using first for powder. Then I find a powder node that gives good speed and groups well (.5 moa or better) and then start experimenting with the jump to tighten things up even more.

How do you do it. I'm open to new processes.

Thanks

 

[Larryh128]

Way I do it. Opinions will vary but I think you need a starting point before you mess with seating depths.

 

[gme]

some may disagree but this method has worked well for me
http://optimalchargeweight.embarqspace.com/

 

[thefitter]

I just realized I did not put this in Reloading... :

Can someone move this?

Thanks

 

[NorCalMikie]

Adjust powder charge for best group. (accuracy) After you found the most accurate node, then start with bullet seating. Change only one thing at a time or you'll end up chasing your tail.

And, I start off with ALL my bullets (except my gas guns) jammed about .010 into the lands. I can always back off from there but so far, I havn't seen the need.

 

[bheadboy]

i always start load workup with a .020 jump, when that seems to provide reasonable groups with one of a number of powders/gr weights , i then begin alter the jump to see if improvement is available.

Bob

 

[artbosco]

How do you go about starting to develop a load for a completely new caliber? My tendency when starting something completely new is to read up on what others are using first for powder. Then I find a powder node that gives good speed and groups well (.5 moa or better) and then start experimenting with the jump to tighten things up even more.

How do you do it. I'm open to new processes.

Thanks

Here's a guide I often use as is, or you can modify it to your needs:

Working Up a Load …. by Lee Euber

1. Polish bullet with steel wool. Initial seating depth achieved when bullet is marked by all lands. Tony Boyer likes to see a “square.” [Although this pertains to the 6PPC, you can modify it for your caliber of choice]

POWDER

2. Load 3 cases in a low grain load. Increase each 3 case load by .5 of a grain, and then shoot. Increase loads until primers show pressure.

3. Identify shots that grouped well, not so good, and then good again.

4. Pick load that shot the best. Load 3 cases with .1 grain less, and 3 with .1 grain more, for another comparison.

5. After picking charge for use, load 30 cases with the same powder charge.

SEATING DEPTH

6. Load the 30 cases in groups of 3, increasing the seating depth from touching the lands to jumping about .040 of an inch, in increments of .005 of an inch.

7. Shoot all 30 rounds without cleaning or clean after each 10.

8. Use ONE fouling shot after each cleaning.

9. Select load that shot best. Load 5 cases with that powder charge and seating depth.

10. Load 10 cases, 5 with seating depth .005 less than benchmark figure and 5 with .005 more.

11. Can compare more than once or change seating depth by .001 or .002.

12. Once you’ve picked the best seating depth, load 15 cases at that depth.

POWDER

13. Check first test by varying charge by .1 grain, for each 5 shot group.

14. Shoot in a medium wind condition, letting the gun do the work.

SEATING DEPTH

15. After picking the best load jumping the lands, compare it with the load that touches. Compare these loads again and again, on different days, in varying conditions, deciding which one is best.

16. If it doesn’t shoot to your satisfaction, restart with a different powder.

NECK TENSION

17. If you decide on the load that puts the bullet in the lands, be sure neck tension is tight enough to hold the bullet uniformly.

 

[284driver]

some may disagree but this method has worked well for me
http://optimalchargeweight.embarqspace.com/

+1

 

[JDMock]

I would recommend that one does both. An example would be for a 6PPC using a 65-68 gr. bullet and N133 powder.

29.0gr. 29.5gr. 30.0gr.

At Jam-

.003 off jam-

.006 off jam-

.009 off-

.012 off

.015 off-

.020 off

Shoot 3-shot groups with each seating depth and the three charges. After this one can see that one seating depth will handle all three charges well. From this one can determinehis best load. Of course, one may want to tweek either the seating depth or the charge, but the seating depth that shows the same orientation of groups on the target is the proper seating depth. Good shooting. PS- This system or one close to it is used by Tony Boyer, Jack Neary, Joe Krupa and several other top shooters. James Mock

PS- The charges were selected from previous experience....but, one should try one mild (29.0), one moderate (29.5) and one hot (30.0) . If this is not in your comfort zone, start at perhaps 28.8, then 29.4, and 29.8. Also, Tony has changed his method over the years and he starts at a seating depth which barely touches the lands. He tries three charges at that depth (usually 29.8, 30.1 & 30.4). From that he goes INTO the lands by .002 at a time. He started using this method when he switched to cut-rifled barrels. Good shooting...James

 

[SS427]

I tried the method described above when I got my first 6PPC and after I read Tony Boyer's book. It worked amazingly well. Much better than any other method I had tried before.

I had a load for my 6BR that I thought was the best load, but out of curiosity, I tried this new method. I ended up with a different powder charge, different seating depth, and a more accurate load.

 

[finnaddict]

Here.

Read this post by Erik. He and along with others covers the whole spectrum. Charge weights, how to read the groups and seating depth methods.

http://forum.accurateshooter.com/index.php?topic=3814361.0

 

[thefitter]

I would recommend that one does both. An example would be for a 6PPC using a 65-68 gr. bullet and N133 powder.

29.0gr. 29.5gr. 30.0gr.

At Jam-

.003 off jam-

.006 off jam-

.009 off-

.012 off

.015 off-

.020 off

Shoot 3-shot groups with each seating depth and the three charges. After this one can see that one seating depth will handle all three charges well. From this one can determinehis best load. Of course, one may want to tweek either the seating depth or the charge, but the seating depth that shows the same orientation of groups on the target is the proper seating depth. Good shooting. PS- This system or one close to it is used by Tony Boyer, Jack Neary, Joe Krupa and several other top shooters. James Mock

What determined the 3 powder charges?

Thanks

 

[fx77]

As said by Outdoorsman above...

 

[broncman]

Too much room for group variation in some of the ladder tests. I like the method descrubed by JDMock as it provides a map if all the data is overlayed in a graph. You can clearly see seating depth nodes and accuracy nodes that are common and this shows areas you can then go back to and fine tune.

Track velocity averages, ES for all groups along with powder charge and seating depth and enter them into a spreadsheet, convert to a graph that overlays them and you end up seeing the common points or nodes. Powder charges basicaly give you a target velocity you are looking for as long as you are safe in the pressure sign area..

 

[cjmac]

as you can see there different methods of doing this ... like said before ONE thing at a TIME

 

[mac86951]

I think it is well covered above. The Process Engineer method is to make functional ranges or "windows"
that slowly decrease to wind up at the ideal load. Don't get in too much of a hurry and make small windows as you might jump past the best load for one that isn't quite as good, or might be very picky to external conditions. This will narrow down your experiment set with each iteration of the process. The trick is to keep notes on every detail. You don't want to pick a load if instead accuracy was improved because of cleaning, or less wind. Temperature can help too, you might find a load that is looking accurate, but on the edge of a pressure problem, which might work fine in winter. Likewise your winter load might be too hot in the middle of summer, so be CAREFUL!

Your results will depend on your notes too. I've seen powder lot variations, as well as bullet variations that will need my 'ideal' load tweaked by 10% in powder charge, or 0.005" in jump to regain performance. If you are loading out of a 100 bullet box, I would stop at the end of #3 and pick something within the acceptable range. If I had a 1000 bullet box, I might do two or three iterations, so supply will determine how much you do, and as mentioned several times before change only ONE variable at a time.

1. 'Safe Pressure' Range (initial OAL)
I would first do the powder/pressure test with a listed OAL from reloading manual. Work up to determine range for safe pressures. This determines a "large" window of powder charges. You can do this in groups and inspect the groups for an "accurate" window of powder charges within this 'safe pressure' range.

2. 'Powder Charge Accuracy Window' (note this will be for initial OAL)
Determine a window of accurate powder charges for the initial OAL (say +/- 0.5gr, or 20% don't worry about narrowing it down closer at this time). Ladder Testing works well, as does Group testing at 100y

3. 'Jump Accuracy Window'
Determine an accurate range of bullet jumps to lands (work toward JAM in say 0.010")

4. Repeat #2 with your accurate range of 'jumps' Some go back and repeat #1, its up to you and your results which will deem what you'll need. Go for more accurate loads this time, say 10% or 0.2gr whichever is smaller. Shoot groups with more shots, or several to start comparing without errors. Repeat this experiment in Summer and Winter to get different temperatures.

5. Using powder from #2, repeat JUMP Window experiment within your set found in #3 (say jump of 0.005")

-Mac

 

[masterblaster1]

Great thread gents.

 

[mikecr]

You didn't say whether the load would be for long range or short.
I believe the egg came 1st, and with this I see seating as prerequisite to incremental load development, and test it with Berger's seating test during case fireforming.