Inconsistent velocities with copper solids

[358156hp]

Very interesting. Thanks for sending this info. I'm at the "good enough" stage of this project, and don't want to order more bullets to run another series of tests. So I'm going with liquid Alox. Supposedly, dusting the exposed bullet after seating with graphite powder eliminates the stickiness of the Alox coating.

Oh absolutely, whatever works best for your circumstances. A popular option to Lee LA, is a mixture known as 45/45/10 which is 45% Lee Liquid Alox, 45% Johnsons Paste Wax, and 10% mineral spirits. It is also available commercially mixed from Lars at LS. Johnsons paste wax is no more but there are copies of it available. The big advantage to it is that it goes on thinner, clumps less, dries harder, and is more tack free. There are also other versions of it available.

Some info if you're interested:
https://forum.castbulletassoc.org/th...10-simplified/

https://www.lsstuff.com/

Again, I have no interest in these companies, I'm just trying to help.

[Lost River]

@Clusterfrack

For clarification,

Your original issue was that you were using the same powder charges and you were getting very large extreme spreads w/the copper solids, versus the poly-coats?

Or simply that the copper solids were just having very large extreme spreads?

[Clusterfrack]

Polycoated Bluebullets were highly consistent in velocity at any charge weight, as were XTP and lead hardcast.

The copper solids without lube were mostly consistent, except for low velocity outliers in ~1 in 5 rounds.

Copper solids with lube are now consistent at the charge weight I tested.

@Clusterfrack

For clarification,

Your original issue was that you were using the same powder charges and you were getting very large extreme spreads w/the copper solids, versus the poly-coats?

Or simply that the copper solids were just having very large extreme spreads?

[Clusterfrack]

...I chronographed the Underwood Xtreme penetrator and 200 grain hard cast load. Didn't do the Cutting Edge as I ran out.
The Underwood Xtreme penetrator is advertised as 1,500 fps. These were the first three shots, and I was surprised by how slow the average velocity was, 1,340 fps.
...

I decided to shoot a few more rounds, and they felt noticeably faster. So I shot seven more rounds and they averaged 1,423 fps. Clusterfrack had recently experienced significant variation with two copper bullets in his 10mm, so this got me wondering.

Then I shot five Underwood coated hard cast, and these didn't have as big a variation in velocity.

Lee liquid Alox: heat the bottle in hot water, apply a few drops to bullets in container, tumble, let dry on wax paper.

[willie]

My opinion which may be unqualified. A common reason for larger velocity variation is difference in bullet pull among rounds tested. Variables are brass thickness and crimp pressure and diameter of expander..

Alox can build up in seater die and affect overall length and thus crimp pressure. I doubt that this is a factor here. A guess is that overall length differences caused by press linkage may be. Presses have slop or unintended movement in their linkage when the ram is up and the handle pulled all the way down. Thus, this fact can cause variation in seating depth which affects crimp pressure and bullet pull.

To test the linkage factor, you can fit a hose screw clamp around the ram in such a way that when the case enters the die performing seating and/or crimping. The clamp controls ram travel. Linkage movement has been removed. You can place two headless bolts on opposite sides of the clamp. Adjust by letting the die hit them and force them down to equal length. Then tighten screw.

Back when I tested loads in pistols, I fired the 1st round into the ground. I was convinced that doing this a
lowed the subsequent fired rounds group into a smaller circle. Another opinion. Extreme velocity variations can affect dwell time and hence affect grouping.

Everybody knows that pistols require powder having a narrow range of burn rate and that slow powders are not suitable. The first place I would look is powder choice if I were concerned with variation.

Being out of date, I do not understand using lube on a copper bullet.

[Clusterfrack]

[Clusterfrack]

Tested after soaking in water for 24h. (Primers sealed).