Load Development, Part Two

(In case you missed it, click here for Part One.)

Photo May 01, 12 13 32 PMReloading data for the 155 grain moly-coated LSWCs is sparse. The two books I have on-hand, Speer and Hornady, don’t list any bullets with this weight for 45 ACP.

Fortunately, Hodgdon’s on-line database does and, better still, it includes loads for two powders I actually have on-hand, Hodgdons Clays and Winchester 231.

I should note, the published loads are for plain lead, not the moly-coated I have. Common knowledge is that moly-coated bullets need a bit more push because they are slippery, leave the barrel sooner, and therefore “escape” before being pushed to the fullest extent. More powder equals more push before they “get away.”

While this suggests that a bigger load will be required, it is absolutely vital to remember that the Maximum Pressure and, hence, the Maximum Load, must never be exceeded. Safety demands that the Maximum is the Maximum, regardless of bullet coating.

The Clays load from Hodgdon is tight. It starts at 5.9 grains and runs to a maximum of 6.2. That’s only a 0.3 grain range.

The specifications for the scale I use, an RCBS Rangemaster 750, says it is accurate to ± 0.1 grains. That means that if the scale says a throw weighs 6.0 grains, it could be as low as 5.9 or up to 6.1 grains.

With the Clays limited to a range of 6.0 to 6.3 grains and a scale that is only accurate to ± 0.1 grains, at best there are only two weights I can test, 6.0 and 6.2 without running the risk of exceeding the maximum. For the task of finding an accurate load, Clays with this bullet leaves very little room to adjust up or down for accuracy.

The Winchester 231 loads, on the other hand, run from 6.0 to 6.7. Starting at 6.0 (5.9 – 6.1 actual), I can try four different loads before reaching the limit.

Accordingly, I decided to make some test loads with the 231 at four different throw weights: 6.0, 6.2, 6.4 and 6.6 grains.

But adjusting the throw on the 650 with precision, even with the micrometer powder bar, is time-consuming because there’s more going on here than meets the eye.

Before getting into that, however, let’s have a look at my log book.

* Important note: These are 10-throw totals. Divide by 10 for the load per round.

Step Goal* Actual* Remarks
1 60.0 61.4 Too much
subtract -0.010
2 59.4 Low now, add some back
add +0.003
3 60.0 Exact! Made ten rounds at 6.00 each
4 62.0 (Starting from 60.0) Low.
add +0.010
5 62.6 A little too much.
subtract -0.002
6 62.7 What? The weight went the wrong way?
Play in the gearing? Try again.
subtract an additional -0.002
7 62.1 Good. Made ten rounds at 6.21 each
8 64.0 (Starting from 62.1) Add some but compensate for suspected gear play
add +0.010 then take back -0.004
9 63.4 Need more
add +0.004
10 64.5 Oops, too much
remove -0.003
11 63.9 OK. Made twenty rounds at 6.39 each
12 66.0 (Starting from 63.9) Add some
add +0.010 then less -0.002
13 65.8 Close enough.
Made ten rounds at 6.58 each

* Again for safety’s sake: These are 10-throw totals. Divide by 10 for the load per round.

Some comments are in order.

  • Step #6 – Throw #5 was 62.6 grains and, by subtracting -0.002 on the powder drop’s micrometer adjustment, I expected the weight to go down. But it actually went the other way, up to 62.7 grains. WTF?
    This caused me to pause and consider what might be happening. My first guess was that perhaps there is some play in the gearing of the micrometer. It is, after all, reading out to thousandths of an inch but, if there is any “play” in the gearing, a change of only 1-3 thousandths might not actually move the powder bar’s slug.
    I decided to try and compensate for this over the next several throws by remembering which way I had moved the adjustment previously (plus or minus), and then adding (or subtracting) a couple of thousandths when the direction is reversed.
  • Step #10 – I forgot to do the “compensation” but, nonetheless, the drop decreased. In hindsight, this says my idea about “play” in the gearing is not correct. But at the time I didn’t realize this. (Senior moment perhaps?)
  • Step #11 – I made twenty rounds at the 6.4 weight, ten for the accuracy testing plus ten more to use when aiming the Ransom Rest and fouling the 1911’s barrel before the whole series.

So, what caused the inconsistency noted in step #6? There are several possibilities, one or more of which may actually be happening.

  • “Play” in the gearing and coupling to the slug that controls the powder bar’s reservoir is a possibility but the practice of throwing three loads before each group-of-10 drops to be measured should take that out of consideration with the forces involved in shoving the bar back and forth.
  • Clumping of powder due to humidity or static electricity is another possibility. I live (and reload) in Phoenix Arizona and, on this day, outside temperatures reached 100 — and it was very dry with humidity around the 10% mark. With that, static electricity is a concern. Accordingly, I carefully grounded my 650 to drain away any static build-up, and I wipe the inside of the powder reservoir with an anti-static cling sheet from the clothes dryer supplies from time to time. Still, some clumping remains a possibility if the particles of propellant have been that way since manufacturing.
  • With outside temperatures at 100 degrees, I run a small through-window air conditioner in the reloading workroom but, on this occasion, I started it at the same time I started this reloading session. As a result, temperature in the reloading room and therefore the temperature of the various parts of the 650, the powder and of the scale were all changing. In the past I’ve seen that this doesn’t make for dramatic changes of more than 0.1 to 0.2 grains or a couple thousandths of an inch in bullet seating but, nonetheless, it is another variable.

And undoubtedly there may be other contributors I’ve over-looked.

One person I know, a reloader and Bullseye shooter, says he “thumps” the powder reservoir each cycle to help ensure consistent drops. This would reduce many of the above effects. I’ve contemplated adding something like a cell phone’s “vibrate” device to my 650 but, at least for now, it’s just another item in the “To Do” list.

Next installment: We’re off to the range and the Ransom Rest!

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