STi tubes, 9mm how many rounds without follower problems?

[seanc]

I have a couple 170 mm tubes. With either grams or tti spring and follower I can get 27 rounds in with the factory STi basepad,

When I put either a grams or TTI basedpased on, I can get extra rounds in, but it always ends up the very first round in gets by the follower and gums up the works.

What am I doing wrong?

[Racinready300ex]

I can get 29 rounds of super with TTI follower and pad. Hard to say what is causing your problem though.

[Pat Miles]

You're not doing anything wrong. The stiffener/caliber specific ribs that run vertically on the sides of the tube do not extend down far enough for more than 27 rounds in with an extended base pad. The spring, follower and first cartridge are allowed to extend below the stiffener on the left side and fall over turning the mag into a salt shaker. There are 3 remedies to get the extra rounds in and sitting correctly.

1- Arredondo makes a base pad insert that has fingers extending upward that keep the bullet(s) that go below the ribs in a vertical orientation so they don't tip over.

2- Extend the ribs on the left side of the tube downward so the bottom bullet(s) stay upright and don't tip over. Some smiths can do this for you and can get pricey. I have a steel insert that I made which slips into the STI tube so I can use a punch to extend the ribs.

3- Buy SVI tubes which have one wide stiffener/caliber specific rib on each side and extend down far enough so the bottom bullet(s) don't tip over.

[jnr88]

MBX magazines also provide increased capacity.

[brytec]

I can get 30 in with Dawson pads

Sent from my iPhone using Tapatalk

[echotango]

STI tubes with grams guts, spacer and dawson 9mm basepad fit 28. No issues.

Tried tti basepad with space below the tube and it did as described by OP.

I'm fine with a reliable 28.

Edited May 20, 2016 by echotango

[Hi-Power Jack]

I get 29, reloadable, in my STI 170's.

[seanc]

Thanks everyone. I got that it was going past the ribs, just wondering if I was missing something else.

I was thinking it wouldn't be to hard to spot weld a thin piece if steel below the ribs to remedy. My nephew is a professional welder that works with very thin parts so this is a pretty simple thing for him.

thanks again everyone.

[S&W686]

My STI big stick I get 29 with grams follower and my MBX I am also getting 29.

[Sarge]

Thanks everyone. I got that it was going past the ribs, just wondering if I was missing something else.

I was thinking it wouldn't be to hard to spot weld a thin piece if steel below the ribs to remedy. My nephew is a professional welder that works with very thin parts so this is a pretty simple thing for him.

thanks again everyone.

I have TTI/Bolen pads with Grams guts in my 170 STI tubes. But can't use more than 4mm pads to keep follower above ribs and also legal. 28 9mm easy

[Ultimo-Hombre]

When I started shooting open I set up STI tubes with Dawson pads and grams guts. Was able to get 29, tight but worked +1 to start. (30 in the gun) after a while I started to get rounds under the follower and reliability problems ensued. I suspect it was the springs breaking in or something. A malfunction totally kills a stage whereas 1 less round in a big stick... Meh.

Nowadays I don't push it. 28 in STI's and 29 in MBX's

Reliability over capacity has served me well.

[seanc]

When I started shooting open I set up STI tubes with Dawson pads and grams guts. Was able to get 29, tight but worked +1 to start. (30 in the gun) after a while I started to get rounds under the follower and reliability problems ensued. I suspect it was the springs breaking in or something. A malfunction totally kills a stage whereas 1 less round in a big stick... Meh.

Nowadays I don't push it. 28 in STI's and 29 in MBX's

Reliability over capacity has served me well.

Mine seem to slip past at 28 though, I just want 28 reliable, not trying for 29/30.

In any case, fix's above offered, I wasn't missing some mysterious thing and know how to get where I need to be.

[Ultimo-Hombre]

When I started shooting open I set up STI tubes with Dawson pads and grams guts. Was able to get 29, tight but worked +1 to start. (30 in the gun) after a while I started to get rounds under the follower and reliability problems ensued. I suspect it was the springs breaking in or something. A malfunction totally kills a stage whereas 1 less round in a big stick... Meh.

Nowadays I don't push it. 28 in STI's and 29 in MBX's

Reliability over capacity has served me well.

Mine seem to slip past at 28 though, I just want 28 reliable, not trying for 29/30.

In any case, fix's above offered, I wasn't missing some mysterious thing and know how to get where I need to be.

Oh.

That's odd.

28 should be ok. Is this just one tube doing this?

If so I'd consider sending it back.

Not being able to get 28 reliable with aftermarket pads and guts is abnormal in my opinion.

Good luck amigo!

[EkuJustice]

I can get 29 with grams follower and spring and TTI 4mm pad. I use a TTI spacer that I epoxy in so it sits higher and dosent drop below the bottom of the tube. I use E6000 and run a bead down the middle then spread out with finger. It holds tight and is vibration and shock resistant so won't crack and fall off spacer has been it like that over 2 years. You can get 28 rounds with factory base pad and spacer and grams guts. With grams I do like the feedlips a little tighter to control the follower more. One of our Jr shooters is using the factory base pad setup and is 22 and 28 rounds