300BlkTalk

Not new to reloading but new to reloading the 300blk. Have heard good things about the Speer 125gr TNT and wanted to do some testing to see which loads will work well with my custom AR-15. All the published load data apart from Hornady and Hodgdon have the max charge of H110 being around 17.8gr. Hornady lists a 125gr at 18.8gr of H110 and Hodgdon states 18.5gr. Anyways, I see a lot of folks on forms who run 19gr all day with no issues. Just wanted some insight on starting from 17.5gr and working up to 19gr with COAL varying from 2.100" to 2.150" with the 19gr rounds.
Side note, this was a first for me, I made a dummy round to find out the max length that would feed and my round is coming out longer than when it went it. 2.150" upon clambering and 2.168" after manual extraction? Tight chamber maybe?

Check your crimp or neck tension, make sure the necks are clean.

More load data, 19 grains with H110/296 is no problem if you work up to it.
https://sierrabulletsblog.com/2017/12/2 ... load-data/

I think the slug is pulling its self when it chambers. Needs a crimp.

I load mine with 16gr of h110 with a wsr primer at an overall length of 2.050. it seems like when taking it to 2.15+ the bullet doesn't seem to be seated in very far. That is with the same 125gr Speer tnt round