So I am working on training and starting to compete more and more but my local steel match on Monday (they don't really care what you do as long as it's safe) and idpa matches have rules that I understand and follow.

Now that I'm leaning towards 3 gun and possible uspsa matches I'm curious about mixing magazine counts. I run my stock SR1911 (paying for a wedding so I won't be buying a new gun until after October) I've got 6 8 round mags, 1 ten round, and 1 seven round.

My thoughts are (if legal) to use the 10 round as a Barney mag and start with the 7 round. Thus essentially giving me 1 more magazine so I can have 6 on my belt and 1 in the gun for a total of 56 rounds.

Can I legally do this? I figured mixing 7, 8, and 10 round mags all Willy Nilly would be illegal but this seems like it's possible.

I don't think I need that many mags but if one guy with a double stack has 5 mags he's carrying 75... I'm no sharpshooter either so I would like the extra mag

I'm not sure of 3gun,I shoot USPSA, and in that, you can use any magazine that keeps your gun within the size limit. It only matters how many rounds are in the magazine at the start of the timer, and the division you shoot in determines that. For instance, I shoot Production Division, and I have both 10 rd mags and 16 rd mags. At the start of the timer I can only have 10 rds in each of the mags I use in the match. Meaning I can have a 16 rd mag as a Barney mag, as long as it's not used in the match. Hope this clears it up! Also here's the link to the USPSA Rulebook

https://www.uspsa.org/document_library/rules/2014/2014%20Rules%20Changes.pdf

I would recommend shooting Single Stack in USPSA so you get Major scoring and are more competitive.  Production would be a waste with that gun.

I'd use the 8 rounders to start and use the 7 as a barney so you could use it in the match just in case.

I shoot USPSA Production.

I am limited to 10 rounds per mag.
I have 10, 17, and 18 rounders.

I just load them at 10....except the 1st one, its 11, unless I have to put it on a bbl, can, chair, or hung from a tree.