Order of march, Velocity Sweetspot or Bullet Depth Sweetspot.

[mlcasmey]

I'm starting to load for bolt guns now along with my AR types, so I can actually find a Bullet Seating depth sweetspot without having to worry about it fitting in a magazine. My question is what do you do first. Find the sweetspot for velocity of Bullet seating depth. I assume they interact in a way that means one has a greater affect on accuracy and should be done first. So if I load tests for velocity first what depth should I pick? And if I load for depth, what velocity should I use. I've read quite a lot about incremental loading tests for velocity and used if for my magazine fed AR's, but they never really address the affect depth has on the test.

Mike.

 

[necchi]

" I've read quite a lot about incremental loading tests for velocity and used if for my magazine fed AR's, but they never really address the affect depth has on the test."

You should try some of those incremental tests, they actually work quite well.
Now to your question; People do it both ways ??? :
And both ways are correct. It's simply a matter of personal preferance and basic elimination of 2 variables we as loaders have. It really depends on your gun and it's chamber. Is it a factory with a larger chamber or is it a custom with tight tolerances?

I generally go .020 over sammi and run an OCW for charge, then go back and mess with seating moving out,,then back to a smaller range of charge weight to dial it in.
Others will start at say .020 off the lands and load for charge weight then start stuffing the bullet or pulling back. Bolt guns are still limited by the magazine length unless your loading single.
Someone that knows their gun well from previous loadings may start with a jam and leave it there,,?? (loading single ALL the time)

My point is there isn't a carved in stone proper way to find your best load, beyond working with both variables, keeping it safe and constantly watching for pressure signs as you change things.
Hope that helps,,

 

[artbosco]

I'm starting to load for bolt guns, so I can actually find a Bullet Seating depth sweet spot. My question is what do you do first. Mike.

Here is a response I provided on another thread where velocity was the issue:

The best way to use a Chronograph? Tune your load first.

Find the best bullet, powder, primer, seating, and neck tension combination for your barrel that puts bullets through the same hole or creates tight clover leaf groups.

When you've achieved that: Then chronograph the load and record your velocities for future use of the same powder but of a different lot. That will help you get close to your tune with the new lot.

There's nothing magical about a chronograph. Most folks try to back into the best load by using the chrony/chronograph first. That's time consuming and more often than not an aggravating experience.

To tune for the load you should try something like this FIRST:

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.” (My added comment.)

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.

Once you've found your best load then you can fine tune even further by trying different neck tensions via a F/L sizing die with BUSHINGs. Have fun!

 

[mlcasmey]

Now that is a heck of a procedure. Reminds me of my old days test flying for the military. Let me print this out and study it a bit. Too bad I'm retired deep in frozen Minnesota and will have to wait till spring to put all of this into practice.

Thanks!!!!!!!!!!

Mike.

 

[carrollshooter]

I have a different procedure that I use although I cannot disagree with the one Outdoorsman posted. With a new gun or barrel I start with one type of bullet. I load a medium load using several powders that have been known to produce good results with that weight of bullet and cartridge. Usually this is five or less powders. I chronograph these for two reasons. If two or more loads produce good groups I look at the chrono data to see if there is a significant difference in extreme spread or average velocity and make a decision on which powder or powders to pursue based on those criteria. If there is no sign of excess pressure I might go up about 2 or 3% in powder charge and try that test again. After I select the powder I want I then adjust seating depth and charge weight (one at a time of course). The most uniform velocity loads are not necessarily the most accurate at 100 yards. Uniform velocity becomes important at long ranges because of vertical spread. Thus the most accurate load at 100 yards may not be the most accurate one at 600 yards. This is more work but I have an advantage over most people in that I have my own private range with covered bench in by back yard. This may be too much hassel at a range used by many people. Part of the fun of shooting is testing loads and recording the effects of variables as you make adjustments. Load, test, shoot, enjoy.