.40 S&W Compressed Load - Unique and 180 gr

[hpops]

Back when the bullet shortage was at it's worst I was able to buy some "pulled" .40 S&W bullets from Rocky Mtn. Reloading that were advertised as Federal HST 180gr. The majority were 180gr with a lot of other weights mixed in, but that is another story. I was wanting to load some of these 180gr. bullets with Unique powder, and Alliant website shows a 180gr. Gold Dot at 6.7 gr with 1000 fps out of a 4" barrel with a 1.12 min COL. Handloads.com shows an unidentified 180 JHP at 6.4gr and 1.125 COL with a velocity of 1065 and a pressure of 33,800 psi, also noting a 5.8gr starting load suggested. So I started to load some new Winchester brass at a load of 6.0gr. When I dropped the Unique and looked in the case and then looked at the bullet it appeared that there wasn't much room left in the case to seat the bullet to correct depth. The bullet has a length of 0.640 in, the case is 0.842 in for a total of 1.482 in. and subtracting the MAX COL of 1.135 for this cartridge leaves a seating depth of 0.347 in. I measured the depth to the powder in the case (which has some variation since it is Unique) and got around 0.300 to 0.310 in. So my question is....does this difference of roughly 0.025 to 0.050 cause this to be considered a compressed load? I don't see any references to compressed loads with Unique and 180 gr. JHP bullets anywhere, even with 6.7 grains and 1.120 COL so this has me puzzled. Nor do I have a 180gr Gold Dot bullet to measure and compare to the HST. I realize that compressed loads are not necessarily unsafe, but without a reccomended load from a good source that notes that it is a compressed load I am a little reluctant to proceed. With a flake powder like Unique 0.050 in doesn't seem like hardly any compression, but wanted to get some more knowledgeable opinions before I proceed. Shooting from a Glock (gen3) also doesn't help the situation either. So please jump in with your thoughts. Thank you.

 

[Kevin Rohrer]

6.7 gr is a max load according to Alliant. Bump it down to 6.0 and see what happens.

There is no problem with compressed loads, but I doubt that you are getting one unless you are seating the bullets too deep. Don't overthink this.

 

[LiveLife]

While SAAMI max length for 40S&W is 1.135", I found most factory barrels to accommodate longer OAL/COL to 1.143" - 1.155" (depending on TCFP/RNFP bullet nose profile) which also improves accuracy from reduced gas leakage. So determine your max and working OAL then calculate your max case fill. Using longer working OAL should allow you to use more powder - http://www.thehighroad.org/showthread.php?p=9639622#post9639622

Comparison picture of RMR 180 gr RNFP loaded to 1.135" vs 1.155"