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Aforum55

170mm mags with 28 rounds

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Just had some 170 STI gen 2 mags tuned and put grams springs and followers in. Loaded to 29 rounds, the first round nose dives and won't chamber. Run 28+1 and it's no problem. Springs are brand new so I loaded mags to sit for a day or two. 

How many rounds is everyone getting in a big stick? 

 

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Mine hold 28

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28 with my own basepad and follower.Tried extremely low follower and decided that 28 is all it can do if mag is no longer than IPSC 170mm limitation allows. 

 

 

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28 with the gen 2 Sti mag. If i use a gen 2 mbx 170 I can 30+1 if I leave it with 29 loaded first night. Worth the extra money imo

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Fully reloadable 29 in my MBX mags.  I could barely squeeze 30 in, but it definitely would not be reloadable.

 

Leave your mags fully loaded for at least a week.  I generally do for two weeks.  After the springs take a set, you should have 29 with a little room to spare.

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I've been getting 29 in my STI and SVI Gen I's for a decade.

 

How did we lose a round going to an improved version ?

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I can get 29 in my STI gen 2 170’s with a tiny bit more room than my old style SV big stick. 

 

Grams spring/follower and Taran 3mm pad

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Sti gen 2 grams springs and followers TTI pads 29 reloadable 

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I've loaded the springs and will see what happens once they settle in. Seems like 28/29 is the standard u less you go with MBX. I'll let ya know

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Whenever I see anything with round nosediving related to magazines, I immediately think adjust the feed lips.

 

And it’s always worked for me in the past.

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Just did that. All feed lips are now perfect. Have to run 28+1. Can't start with 29 to start

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Posted (edited)

Even perfect feed lips will nose dive the first round if the spring is too strong. 

If your springs don't take enough set, you can go to a TTI +1 follower and spring  Add a gen2 3mm pad and you will easily get 29, possibly 30.

Edited by zzt

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29 re-loadable in a mbx 170 but can start with 30 + 1 if want to . When the springs are new i can't fit the 30 but after a bit of use it works.

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29 in ST mags with grams or TTI guts (28 reloadable) and 30 with MBX mags (29 reloadable). This would be for 9 major.

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17 hours ago, Aforum55 said:

Just did that. All feed lips are now perfect. Have to run 28+1. Can't start with 29 to start

Fool around with different bullet shapes.  Something with more of a shoulder that contacts the feed ramp higher would be my guess.  Feed ramp adjustment or longer COL might help too.

Try to simulate the failure with dummy rounds and take a very very close look at what's going on at the bullet/feed ramp.  That should tell the story.

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Sorry: only SV mags.  In general, reloadable 29-30.  Either a TT follower (and tuned by TT) or silver SV adds an extra round, 31 sometime reloadable but mostly non-reloadable.

 

Again. TT tuned my mags.

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Posted (edited)

With STI gen 2 tubes, Grams guts and TTI 3mm base plates I get 29 reloadable in 2 of them and 29 but not reloadable in the other 2. But it took a little while before I could reload the 2, they were too tight at first. The other 2 are just too tight so I use them to start with and save the others if I plan on reloading to big stick.

Edited by NamesNotMike

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Dang, I get 29 pretty easily in my STI with grams. I only get 28 in my SV's though. I have heard that removing some material in the bottom of the baseplate is helpful but I haven't had to do that in the STI. 

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