Boolits Lengthening When Sized Down

[NVcurmudgeon]

BruceB referred to this phenomenon in his .404 mould thread. Not wishing to hijack his thread, I am posting a little experiment of mine here. I measured five unsized Lyman 314299 boolits from one cavity of my mould. They were all 1.172-1.173" long as cast, with a diameter of .314" to .315" (out of round.) Next I sized them to nominal .314". Diameter remained measureably unchanged at .314 to .315", still out of round, with length increasing to 1.174-1.175". It appears that very little sizing took place here, with only a slight increase in length. Finally, the same five boolits were sized to nominal .310". This time there was a substantial increase in length to 1.180 to 1.181". Diameter went to .3105", nice and round this time. Not as dramatic an increase in length as BruceB reported, but more than I expected, course we all knew already that squeezing boolits makes the metal go SOMEWHERE. These boolits were cast of ACWW + 2% tin, and not gas checked, as I wanted to measure only the changes in the cast boolit.

[grumpy one]

So, where does this leave the theory that sizing bullets only "works" the surface of the driving bands? To get longer the whole bullet would have to be worked, and the whole bullet should lose hardness.

[Bass Ackward]

Yes the whole bullet is worked. And the bullet sizes two ways. It sizes forward from the half way point and then extends backward from the center following the path of least resistance. It is also why sizing bullets that were water dropped is a negative too. You disturb the structure through and through and won't get what you expect.

This effect is why I nose first size. If a bullet base is allowed to be unsupported while this .... lengthening is going on and you have an air bubble in the base, this defect will need to compress before lengthening continues. In the mean time the other part of the bullet continued. So you get a base out of square. Pushing from the back end prevents this by keeping the path of least resistance as forward. Now some will argue that a defective bullet is still a defective bullet, but I have taken bullets weighing as much as 5 grains in weight difference in 35 caliber and still held 1 1/2 MOA.

This is another reason that sizing cast gained the bad reputation it has. But if you only size say .001 to true up it doesn't really seam to matter.

[StarMetal]

Bass,

A member sent me a handful of his reject Lyman gaschecked 45 Colt bullets to make a gascheck tool for. The bases were good enough for measurements. Anyways I took six of these very badly filled out bullet and loaded them over 9.0 grs of Unique and fired them out of me Smith Model 25 for the hell of it. I was shocked. three bullets into one ragged hole, the 4th openned it to one inch, and 5 & 6 were truely flyers. Not shabby at all for BAD bullets. This was at 25 yards by the way.

Joe

[9.3X62AL]

Joe/Bass--

If there was ever a place to "Never say never, never say always", it is the hobby field of cast boolit shooting. About the best we can do is eliminate as many of the variables as we reasonably can, abide by dimensional integrity as much as possible, and do our best at the range or in the game fields. While I strive to do good work with those first two factors, the gun carriage part of the assembly (me) is usually the weak link in the chain.

[felix]

Boolit weight variation typically does not harm a load. It's the out of balance generated by air bubbles. Being able to shoot a good group with boolit weight variation assumes an ignition characteristic which is quite wide in consistency (ideal). ... felix

[NVcurmudgeon]

One of the oldest articles of faith of some casters has been, "sizing cast bullets always ruins them." A somewhat more modern corollary of this is, "sizing cast bullets down more than .00X" destroys accuracy." I believe that these two beliefs may have originated in the bad old days when the leading brand of sizing dies had a pronounced step in them and often produced bullets sized off-center. I saw this deplorable condition myself in the late fifties and early sixties. Today, with improved sizing dies, I have shot many excellent groups with boolits sized down as much as .005". The late Bob Milek once wrote an article describing his sizing .44 CB to .41, and .41 CB to .357. His revolvers gave good accuracy. Most of my rifle CB are launched at 1200-1700 fps, all are cast of WW +2% tin, and all use either NRA formula Alox/beeswax or Felix's World Famous Lube. It may be that my CB are not operating in very demanding conditions, so I have not been troubled by altered surface hardness caused by unusual amounts of sizing. Shhh! I'm not asking any questions as long as it works.

[Bass Ackward]

Bass,

A member sent me a handful of his reject Lyman gaschecked 45 Colt bullets to make a gascheck tool for. The bases were good enough for measurements. Anyways I took six of these very badly filled out bullet and loaded them over 9.0 grs of Unique and fired them out of me Smith Model 25 for the hell of it. I was shocked. three bullets into one ragged hole, the 4th openned it to one inch, and 5 & 6 were truely flyers. Not shabby at all for BAD bullets. This was at 25 yards by the way.

Joe


Joe,

I agree. I have shot visual inspected bullets rejected by my relatives as inferrior and just whipped the pants off them. The only exception? PB pistol bullets with defects on the base. Here life ain't what it should be.

Felix,

There is so much to be said for full case loads from ignition to lack of filler, to forgivness of sins in bullets. I need every advantage I can get in life. Can't win fair, cheat!

[felix]

BA, you already know how to cheat. Case size for the weight of boolit of choice is number one, and number two is the twist necessary to barely stabilize that same boolit for the entire distance. We are talking no more than 2400 fps max with that boolit at 14 max twist rate. ... felix