Anthonyasphalt wrote: ↑Mon Oct 28, 2019 9:47 pm
The poly tip on the sst is just a little longer, the cannalure's are at roughly the same spot.
ignore cannelure placement. its (mostly) irrelevant to this caliber. those cannelure's are based on
typical bullet seating depths in cartridges like the 308, 30-06, etc.... we just happen to be cannibalizing those already designed projectiles for use in the 300 blackout. Thats not to say that proper and/or published seating depths for the blackout WONT hit the cannelure - all i'm saying is that you needant be concerned if you do or dont happen to hit the cannelure based on published data.
as dellet mentioned, once you get some experience under your belt then you can experiment if you want to start fiddling with OAL, but that requires GOOD data on YOUR guns before you can start to do so
SAFELY. for now... just work within what is known good info and go from there.
wildfowler wrote: ↑Tue Oct 29, 2019 8:32 am
I’m looking at page 382 of my Hornaday ninth edition book and they list eight different 150 grain bullets including the 150 SST and the 150 FMJ-BT as having an oal of 2.2”. And using 1680 powder list charge range from 15.4 - 22.0 grains.
first off - you need to reference the published errata data that hornady has online. if you look there you'll see that the OAL for the 150fmjbt has been Corrected to 2.090" and that the SST is 2.210" for hornady's 9th edition. please follow the following link to get that data to update your manual
https://press.hornady.com/assets/pcthum ... 702177.pdf
i highly suggest that you print that out, stuff it in the front of your book and make notes on the appropriate pages for calibers you reload.
for those using other versions - the full current list of errata is published here
https://www.hornady.com/support/load-da ... ook-errata
the takeaway is this - punishing errors happen. thats one of the very reasons that the rule start at minimum and work up until you see pressure signs. that way even in the event of an incorrect OAL published, you're significantly less likely to hurt yourself. the 2nd takeaway is - dont just automatically follow what you see online for reloading data. if a major publisher can make a typo, *ANYONE* can. try to find *similar* data before you go ahead with stuff, especially those of ya'll out there who are relatively new to reloading. you cant be TOO careful.
These eight Hornaday bullets all have the same load data even though as you discovered the ogive is in a different position for various bullets.
while ogive placement is important to the discussion, i would suspect that the *primary* reason they can share the same load data is that their seating depth - how far the bullet goes into the case and therefore case capacity left for powder - is nearly identical based on the varied recommended OAL. Sadly my selection of 150gr bullets is extremely limited so i cant give a proper comparison, but based on the fact that max load data is based on safe max pressure, and pressure is directly proportional to case capacity/seating depth... logic would tend to support the theory.
The 300 blackout has a relatively generous throat/lead area of the chamber (compared to other calibers), so while jamming a bullet into the lands before exceeding mag length is possible, there arent very many bullets out there that can do so without exceeding mag length. some of the light for caliber bullets will literally be falling out of the case mouth before they can even touch the lands. so bearing that in mind, you can see why for the most part people dont worry about it other than as a benchmark for consistency on our reloads.
so unless you have an out of spec chamber with a short throat, or are loading beyond mag length to try to increase velocity, you should be in pretty good shape of not worrying about a bullet jamming into the lands causing pressure issues as long as you stay with published data below max mag length of 2.260" oal.
hth