Short oal and pressure

[Garmil]

Is there an equation to use for figuring pressure on loads other than what is published?

Just started loading 125gr rn blue bullets and to pass the plunk test i have to load at 1.08.

I'm using csb-1 powder 3.8 gr and getting about 1020fps.

Just wanting to make sure this is safe.

[cnote]

Lots of guys run loads that short for their CZs,

Same advice as always, start low, work your way up to desired PF

always checking for signs of pressure.....etc.....

[rtp]

I load several bullets in 9mm to 1.065" between a CZ and PPQ...I find the shorter OAL worth .1-.2gr in 'most' powders, meaning I load lighter by that much vs someone loading at 1.10-1.15" OAL, but - YMMV, no exact formula, and different powders behave differently, etc.

Short version is I don't randomly go beyond mid-range loads w/out chrono when loading short, but also am not particularly concerned by loading short, either.

Edited November 17, 2014 by rtp

[Garmil]

Thanks that helps a lot. My load data says 3.8 to 4.4 for a 124 rn but they don't give an oal.

[Steve RA]

CSB-1 is roughly equivalent to Unique, according to a commercial reloading friend, so it should not develop any unexpected pressure spikes that might occur with one of the really fast powders.

[Garmil]

CSB-1 is roughly equivalent to Unique, according to a commercial reloading friend, so it should not develop any unexpected pressure spikes that might occur with one of the really fast powders.

Thanks I had heard universal but that's real similar to unique. I've shot a few of them now and they are working good and feel nice and soft so I should be safe.

[noylj]

1) The whole concern about COL and pressure started when one company printed their findings about bullet set-back.

The round went from ~30,000 psi at std. COL to ~60,000 psi when the bullet was pushed back 0.25" (¼"). No, there is no formula to calculate the effect a change of COL will have, as it would be dependent on the powder, the case geometry, and the bullet geometry. For normal COL variation, the change in pressure is very small.

2) Find the COL that works in your gun (load a couple of inert dummy rounds and use them to test function) and then work up your load from the starting load. Did you work up the load to where you are or did you jump right in?

3) Best accuracy is generally with the bullet bearing surface as close to the lede/rifling as possible and load work goes from there.

4) Other powders may be similar to Unique, but that does not mean they are as well behaved.

Edited November 18, 2014 by noylj