Fluctuations in COAL

[OHW]

While seating 55gn FMJBT Winchester WB556MC55 with a Lee die in a Lee single stage press on mixed brass trimmed to 1.750 < I'm seeing a fluctuation of 2.238 to 2.214. Die set to 2.225. The long ones I spin and reseat to get down to 2.228<. the short few I left alone as the collet is still visible.

I stoped using a turret press to get better results. It seems the fluctuation is about the same.

Is this normal? Are the Winchester components irregular ? Or is it the seating die?

Also I got a Lee turret press and spare turret for sale. Only 100 rounds on it.

[30Cal]

It's the bullets. The seating plug doesn't push on the tip; it pushes closer down to the ogive which is what matters. OAL vary quite a bit even with match bullets--don't chase it; the seating die is doing its job just fine.

[rsrocket1]

If you measured with a cartridge length gauge rather than measuring off the tip, you would probably see much more consistent readings.

[gorblimey]

If you measured with a cartridge length gauge rather than measuring off the tip, you would probably see much more consistent readings.

This!

[Pubert]

Great question! I was wondering the same thing. I figured as long as all of my rounds were greater than the suggested COL that I was ok, but was wondering if variation in the length was standard.

Thanks for getting it answered!

[gorblimey]

Great question! I was wondering the same thing. I figured as long as all of my rounds were greater than the suggested COL that I was ok, but was wondering if variation in the length was standard.

Thanks for getting it answered!

Those cartridge dimension specs are all maxima for standard chamberings and typical bullets. The goal should generally be to stay under them, rather than exceed them. COAL is a somewhat fuzzy number, though, and needs to be determined for your specific situation:

http://www.gunsamerica.com/blog/case-overall-length-coal-reloading-tips/

In sum, since chambers and bullet profiles are different, you empirically determine the seating depth that has the bullet touching the lands, and that's your COL/COAL for that chamber and bullet. Then seat it 0.020" deeper and adjust the jump up and down during load development.

[30Cal]

In sum, since chambers and bullet profiles are different, you empirically determine the seating depth that has the bullet touching the lands, and that's your COL/COAL for that chamber and bullet. Then seat it 0.020" deeper and adjust the jump up and down during load development.

A little bit of a moot point with FMJBT. They'll be way out past magazine length before you get even close to the lands; even worse with a standard factory barrel.

[OHW]

A quick follow up. Today using the same case OAL in the same seating die, untouched for COAL, with Silver State Bullets 55gn FMJBT. The fluctuations were minimal, from 2.2245 to 2.228 most at 2.225 just as planned. Only 2 of 50 came in short at 2.220. Not bad. I think I will skip on the Winchester in the future.

Thanks for the case measure device idea. I think I saw a thread somewhere on making one. ????
Also does anyone have another source of consistent bulk component bullets?
Thanks for all the responses.

[Pubert]

Those cartridge dimension specs are all maxima for standard chamberings and typical bullets. The goal should generally be to stay under them, rather than exceed them. COAL is a somewhat fuzzy number, though, and needs to be determined for your specific situation:

http://www.gunsamerica.com/blog/case-overall-length-coal-reloading-tips/

In sum, since chambers and bullet profiles are different, you empirically determine the seating depth that has the bullet touching the lands, and that's your COL/COAL for that chamber and bullet. Then seat it 0.020" deeper and adjust the jump up and down during load development.

Whoa, that was kind of over my head - I'm loading for handgun, does this still apply? Can you explain this a bit more? I thought I had read that if the bullet is seated below the COL, then that could cause too much pressure?

Thanks

[gorblimey]

Whoa, that was kind of over my head - I'm loading for handgun, does this still apply? Can you explain this a bit more? I thought I had read that if the bullet is seated below the COL, then that could cause too much pressure?

Thanks

Oh, I see what you mean. The OP was talking rifle, I erroneously assumed that you were as well.

I mostly reload for bolt guns, slowly and anal-retentively, so the high-volume pistol stuff is over my head.

From first principles, though, it makes sense that for the relatively short and wide pistol cases, small reductions in COL can result in significant reductions in case volume and consequent increases in pressure.

Given a recipe that works well for your particular gun and reloading components, I suspect you're absolutely right to watch for rounds that deviate from that recipe (especially to the low COL side).