Process questions...

[daved20319]

When loading test ammo, say you're trying out a new powder, what charge increments do you use, and how many rounds do you load at each increment?  And what range do you test at?  I realize the latter is dependent on the type of shooting, for now, assume targets and small groups as the goal, vs. tactical or gaming.  If it matters, I'm currently focused on .45 ACP for my 97 BD.  Later, and thanks.

Dave

[painter]

It depends on the load window, to a degree. If the load window is large, say 10 grains, I'll load 5-10 each at .2 grain increments then drop to .1 grain increments when I find the range in the window that performs best. If it's a short window I'll load 5-10 each at .1 grain increments. I rarely go all the way to max load, unless accuracy is best with the testers close to max.

YMMV.

[daved20319]

Well, you just described my process, so thanks fo being reasonable and doing it my way  .  Later.

Dave

[Wobbly]

? Painter told you basically what I do. The way I achieve my numbers is to divide the "load window" by 5. In that way a powder with a range of ~1.0gr with end up with 0.2gr increments.

? You don't want to load more than about 8 rounds per increment. Not all these tests work out, and sometimes you end up spending a long time with your kinetic hammer. That's not fun at all.

? I like to do all my accuracy testing at 30ft, or 10yds. That way I can compare targets from 10 years ago to ones I do today. If I had it to do over I might pick slightly further out, but it's done. Definitely not closer! The other thing I did was buy a 500 pack of 5x8" single bull targets. These store easily and I know I got the same sight picture for all my testing.

? I'm also aware and will admit to myself that from time to time I have flyers on those targets. If the light is strange or the old eyes are giving trouble, then I'll allow myself to ignore the worst hole on the target. Hey, I'm human. 

 

[M1A4ME]

It depends on the load window, to a degree. If the load window is large, say 10 grains, I'll load 5-10 each at .2 grain increments then drop to .1 grain increments when I find the range in the window that performs best. If it's a short window I'll load 5-10 each at .1 grain increments. I rarely go all the way to max load, unless accuracy is best with the testers close to max.

YMMV.

Works for me, too.

[daved20319]

? Painter told you basically what I do. The way I achieve my numbers is to divide the "load window" by 5. In that way a powder with a range of ~1.0gr with end up with 0.2gr increments.

? You don't want to load more than about 8 rounds per increment. Not all these tests work out, and sometimes you end up spending a long time with your kinetic hammer. That's not fun at all.

? I like to do all my accuracy testing at 30ft, or 10yds. That way I can compare targets from 10 years ago to ones I do today. If I had it to do over I might pick slightly further out, but it's done. Definitely not closer! The other thing I did was buy a 500 pack of 5x8" single bull targets. These store easily and I know I got the same sight picture
for all my testing.

? I'm also aware and will admit to myself that from time to time I have flyers on those targets. If the light is strange or the old eyes are giving trouble, then I'll allow myself to ignore the worst hole on the target. Hey, I'm human. 

 

Still right in line with what I'm doing, although my previous testing was done at 40', that'll teach me to pull out the tape measure BEFORE I start shooting  .  I also load 10 rounds per increment, that gives me two 5 shot groups per charge, helps even out those momentary lapses in concentration, or even just fatigue.  I also test round robin style i.e., if I have 5 increments, I'll put up five targets, then shoot one of each charge until I have 5 on each target, vs. 5 of the first increment, then the next, etc.  That also helps level out variables, both in the shooter and the gun.  I don't bother saving targets, I just take pics then run it through On-Target so I know what I REALLY did, not what I told myself I did  .  Yeah, I'm human too  .  Later.

Dave

[IDescribe]

First, pick your test parameters and stick with them forever.

I found that there were differences with SD based on 5 round  strings vs 10 round strings, but not significantly so  between 10 round strings and 20 round strings, so I do 10 round strings.

After you have a lot of test data in the books, you can take a bullet you have never shot, and you can reliably predict how it will perform with a powder you are familiar with.

Like Painter, I will break a ladder up based on the size of the load window.  If my load window is 3.6 - 4.2, my ladder probably goes:
3.6
3.8
4.0
4.1
4.2

I used to test accuracy (and chrono) at 30 feet.  When I switched to coated lead, I found that groups were simply TOO similar, so I switched to 45 feet to make differences more easily visible and measured.  Sticking with same distance is valuable as it allows you to look at a lot of targets and simply by visully comparing them to past targets in memory, say "Nope, not acceptable.  This does not meet my standard."

After identifying most accurate load, retest at/around that load with small OAL tweaks. 

When you chrono or test accuracy, tap the magazine back down on the tabletop before inserting into pistol. This breaks up any clumps, improves consistency of powder position, and makes the burn more consistent. I can't say for sure that it improves accuracy, but it does improve SD.


edited to fix a couple of type-os and improve clarity

[M1A4ME]

You don't mean "clumps" as in the powder sticking together due to moisture/degradation, etc.  Do you?

I "assumed" you meant move it towards the back of the case vs. being piled up at bullet end or not in consistent locations in the case.

Do you mean tap the back of the magazine on the table to help get the powder near the primer flash hole?  Or tap the bottom of the magazine on the table?

I think I understand the reason for wanting powder either near the flash hole or consistently in the same position vs. the flash hole.  Though I've never loaded pistol powder for reduced lead bullet loads in rifles I know some people put something in the case on top of the very light powder charge to insure powder stays near/over the flash hole.

Just making sure I understand what you typed and I'm not running into something I'd not heard before.

Thanks for any clarification.

[IDescribe]

I mean tap the back so that the powder all moves toward the flash hole.  NOW, I don't think it stays there.  I just mean to tap in that direction.  Once the slide starts cycling, the powder is going to do what it's going to do.

My understanding is that the tapping is just to get all the powder particles moving freely from one another.  I quite frankly don't know what powder is doing inside the case after a loaded cartridge has been sitting around for a while.  But I did find SDs to improve when I started tapping the mag before inserting into the pistol.

[M1A4ME]

I've not seen evidence of clumping together in powder cans when I pour powder out.  If I did, I'd be afraid it was degrading and not safe to use.

I started to also mention powder from cases I'd pulled bullets from, but by the time I smack that kinetic puller three or four times on the concrete floor that wouldn't be a good example.

I do believe consistent powder location in relation to the primer makes a difference.  The most accurate loads I ever fired through my rifles (M1A and 03A4 at longer distances were loaded with IMR4350 and were compressed loads.  So far, the most accurate 9MM loads I've made for my CZ's is also a slow burning powder that results in a compressed load.

I'm not saying you can't have accuracy with fast burning powders as my best .223 loads years ago in the M700 and today in the AR15's are with a faster burning powder that doesn't fill the case.

But sometimes, it works out that way.

[Pistolet]

First, pick your test parameters and stick with them forever.

After identifying most accurate load, retest at/around that load with small OAL tweaks. 

edited to fix a couple of type-os and improve clarity

How much is a small tweak in 9mm and in .45ACP? And how much would be too much?

[Wobbly]

I do believe consistent powder location in relation to the primer makes a difference.  So far, the most accurate 9MM loads I've made for my CZ's is also a slow burning powder that results in a compressed load.

With 9mm it's fairly easy to get good case fill with most any powder. Where you really need to watch out is 38 Spcl with dense powders like TiteGroup. With light loads of TG, it actually makes a difference in velocity and accuracy as to whether you point the gun up or down before you fire.

[Wobbly]

How much is a small tweak in 9mm and in .45ACP? And how much would be too much?

I'd have to say that depends more on the powder than the cartridge. You can see big changes in a powder like TG with a change of 0.1gr. With more moderate powders like HP38 and W231 you can see a change on the chrono with 0.1gr, but only a measly ~5 fps. If you want to see a change on the target, then it usually takes 0.2gr or more.

"How much is too much" depends upon which end of the charge spectrum you're looking at. A graph of Chamber Pressure vs. Amount is not a straight line, it's a steep curve. Changes of 0.3gr at the lower end of W231 will start getting results faster. (Often though, with gaps you need to go back and fill in.) However, changes of 0.3gr at the top end of the scale can push you into danger areas without any warning.... especially if you are chasing a specific velocity.

The only data most of us can collect during testing is Velocity using a chrono. Velocity and Chamber Pressure behave in a 1:1 relationship within the "load window". But somewhere above Max Load, the 2 characteristics part ways. Velocity begins to flatten out,  while Chamber Pressure continues to climb. The cartoon below tries to explain this (the safe loading zone is represented by the green oval)...



I'm no expert on any of this, but these are the things I try to keep in mind as I test.

Hope this helps.

[Pistolet]

Thanks for the answer Wobbly. I was also curious about how big is a small OAL tweak as stated by IDescribe, though I suspect the answer will also be that it depends on the powder used. Just like he goes by 0.1 or 0.2gr increments for powder, I'm just wondering what the OAL increments  might be.

[IDescribe]

I consider small .01-.02

And note that as you shorten, you may need to reduce charge weight.  My Shadowline will show definite tightening or widening of groups in particular velocity ranges.  If I determine max OAL for that barrel is 1.14 for Bullet X, and I hit the tightest group at 3.9gr of Powder A, that is the baseline.  If I want to tune for OAL, as I shorten that, I will adjust the powder charge down to keep the velocity the same.  There's more than a bit of trial and error there. 

The reason I personally consider .01-.02 small is that as you shorten OAL, peak pressure climbs, and velocity climbs, and shortening by .02 is not a big enough change to be concerned about so long as you aren't already operating at max pressure.  If you want to go shorter than that, then go shorter, but drop back to starting load and work up a new ladder.  That's best/safe practice, anyway.