What seemed simple at first, got suddenly confusing.

I'm loading for my G20.3 10mm, but I also have a kkm 40 s&w conversion barrel for it. Normally all I ever shoot is 10mm, yet wanted to try the 40 s&w route for something different to reload and shoot. Right now, the load is longshot and 165 grain pulled jacketed bullets from RMR. The Lee load data has a min oal of 1.125 and a max of 1.135, but online the min and max oal is all over the place, which seems dependent on mag length (that actually makes sense).

I only have one 165 gr seated to 1.135 out of 30 primed and charged cartridges. Should I or would you go back to the drawing board, dump the powder and start over again with load data for 180 gr bullets (those I have plenty of; xtp, hap and jacketed) and seat those bullets long to fit more of the mag length and use my 10mm glock barrel or continue on with the 40 s&w SAMMI spec for the kkm barrel? All I am wondering about is feeding issues with the 10mm glock magazines using 40 s&w cartridges. TIA

Eric

Set it at mag length and make sure the bullet doesn't contact lands/grooves.

Plunk test is your Huckleberry. If it plunks, it is good to go.

ymmv

The throat or leade on the 40SW chamber is long enough to allow you to load to the limit of your magazine. I load for an M&P40c, and I routinely set the COL to 1.16". My magazines will handle 1.17" before getting wonky.

Always check with the plunk test, but there is no reason not to build yourself some extra pressure margin by loading longer than SAAMI.

You can't do this with 9mm or 45acp, but 40sw and 10mm both have generous throats.

Edit: I just noticed that you are using 10mm magazines. In that case, don't load to the limit of your magazine as the 40sw throat isn't that long. Try 1.16", see if it plunks (it should unless you have a really fat bullet), load some up to whatever and see how well they function.

Thank you, Gentleman!!! I appreciate your advice. I'll seat some more bullets at different oal's, then plunk them into that kkm barrel.

I realized late last night I didn't want to get too far ahead of myself in the reload process with that 40 s&w cartridge before asking for more knowledgeable opinions. It would not be the first time I have had to pull bullets in silent regret for not raising my hand with questions.