Mirror Finish Polishing STI Magazine Tubes

[Tactica]

I'm new to the sport as I've mentioned before here. I realize this may just be a newb question, so I didn't want to clutter up the gun smithing section.

I bought some STI Superior Firearms mags from Shooters Connection recently. They appear to be well worth the price. STI tubes, grams springs and followsers, Dawson base pads, mags are tuned. However, they have almost what I would describe in lamens terms as a galvanized look / feel to them. Finer than that, but not a high polish to the body of the mags. I was 'expecting' to receive a high polish 'mirror' finish tube.

This is probably because my limited STI Edge gun's STI tubes have that 'mirror' polished finish to them. I had a 'perceived' notion that high polish = quality = drop faster.

I called Superior Firearms today and spoke to Joe and talk about these mags. He was quite courteous and patient with this new competition shooter's questions. From memory, he explained that the tubes go through a 3 day polishing process, followed by a soda blast (I don't know what that is). Then, another 2-day polishing process.

I told him I didn't have my new gun yet, but was curious if the mags would drop as cleanly from the 9mm open as they high polish or 'mirror' finish ones would from my Limited 40 gun.

He explained that although the new 9mm tubes may appear to be 'rougher' than the 'mirrored' looking .40 tubes I have, they should drop as fast if not faster than the .40 tubes. He said in his experience, mirror finish creates a larger surface area for binding to occur. He explained that due to the 9mm tubes being polished through his process, they should have very smooth and consistent planes along the body. However, if magnified enough, they should also have millions of microscopic rounded surfaces creating less surface area and allowing the mag to drop fast.

I had no argument, I'm new, this all seemed logical and made sense.

Since I can't 'try' it until I get the new gun in, I was wondering if anyone else familiar with this philosophy or if anyone ever tried different surface tuning to the body of mags. If so, what were the results?

Does anyone swear by high polish 'mirror' like finish? If so, why?

Thanks for your time,

Rob

[Tactica]

I guess this also begs the follow up question... is mirror finishing on mag tubes, bad?

Cheers,

Rob

[Sarge]

From my limited understanding having just gone to 2011 this summer.. The most important part of the mag to polish the shiznit out of is the inside of the tube. This provides smoother function and less chance of any hangups. Polishing The outside of the tube for the most part seems to be cosmetic but to me I think they are slicker when polished so in my mind they will drop more reliably.

As for the Superior mags dropping free, the ones I have seen being used have always seemed to drop free just fine. However, many have needed to have feed lips adjusted right out of the box. Once that was fixed they seem like good mags.

You can put a wooden dowel in a drill and wrap a cloth around it and apply some polishing compound of some kind and polish the inside yourself quite nicely. As for the outside use a buffing wheel or do them by hand.

I read that somebody puts them in a tumbler and polishes them. That might be worth a shot.

Polishing certainly does not hurt a mag. It makes them look good and that is what it's all about sometimes.

[Tactica]

Thanks for the reply. I hadn't read about the cloth and dowel yet. I will definitely keep that in mind.

I understand the inside needing to be cleaned up good. I expected there to be more opinions / feedback on the outside of the mag finish, but I guess they can get plenty dirty in the course of a match... so perhaps if you just keep them clean enough and they are droping, then you are good to go. Hmm.

Cheers,

Rob

[Chris Keen]

Polish up the insides real good. Thats where the real problems occur.

[want2race]

You don't want the top round to pop out of the feedlips too early. If the mag doesn't hold onto that top round well enough it can induce double feeds.

[BlueOvalBandit]

followed by a soda blast (I don't know what that is).

Can't help you on much else but soda blasting is essentially sand blasting with industrial baking soda. It's not as harsh as other abrasive medias and is not very effective at removing rust, works great on removing paint because I used it at home on a car restoration, but it also doesn't pit and peen metal or get it hot. Main thing is you can wash the part and remove the abrasive (soda) unlike say sand which no matter how many times you blow out and vacuum sand still is coming out of places. The soda also resists rust too.

[Tactica]

^ Two the last couple of posters:

Good point about top round. I'll keep that in mind. I wonder if a high polished 'inside' of mag can cause unwanted double feeding... that is, if you get things too fast inside the mag. Hmm...

Also, thank you for the soda blasting definition! I have never read a description of what that process was exactly, but I've heard more than one person mention it. Still not quite sure what value it brings to a magazine tuning, but I suppose it's helping remove any fine imperfections.

Since the new open gun is getting close to being done, I think I'm just going to drop off the mags with the smith and have him double check them all. Make sure they fit to the gun well, etc.

Cheers,

Rob

[Sarge]

I wonder if a high polished 'inside' of mag can cause unwanted double feeding... that is, if you get things too fast inside the mag. Hmm...

That's just crazy talk! Why do you think so many mag tuners polish the insides of mag tubes? To lessen friction, resistance, whatever and make them slicker, faster and more dependable.

[kaiserb]

He explained that although the new 9mm tubes may appear to be 'rougher' than the 'mirrored' looking .40 tubes I have, they should drop as fast if not faster than the .40 tubes. He said in his experience, mirror finish creates a larger surface area for binding to occur.

I would think a nice polished finish would make something smoother, thus it would drop faster out of the gun. Unless this person is referring to binding on a molecular level, in which case he has the surface really, really, smooth

[Tactica]

I wonder if a high polished 'inside' of mag can cause unwanted double feeding... that is, if you get things too fast inside the mag. Hmm...

That's just crazy talk! Why do you think so many mag tuners polish the insides of mag tubes? To lessen friction, resistance, whatever and make them slicker, faster and more dependable.

LOL - got it. Will polish inside. Thanks for setting me straight!

[Simon]

I put my mag tubes in the tumbler for 2-3 hrs with corn cob and dillon polish.

Works for me

[Chris Keen]

That works too. But Flap Honing, or polishing with different (increasing) grits will yield a better surface finish. Takes a little more effort, but so worth it.

PS I know the tumbler will get into corners that the hone, or polish mop can't get into, but the important surface to polish here is not the corners, but mostly the sides, and the front and back a little bit too.

Edited December 22, 2011 by Chris Keen

[ima45dv8]

That works too. But Flap Honing, or polishing with different (increasing) grits will yield a better surface finish. Takes a little more effort, but so worth it.

PS I know the tumbler will get into corners that the hone, or polish mop can't get into, but the important surface to polish here is not the corners, but mostly the sides, and the front and back a little bit too.

Amen.

"Flap Honing" (I didn't know that's what it's called....but it works for me) is an investment that pays huge rewards. That's more work than I'm setup to do, but I know and appreciate the result. I want my springs to move freely. Dragging and the resultant binding are a game-killer.

*Though it hasn't been the focus of this thread, I'll add a word about mag guts.

Chris Paty (CPWSA.com) advised me to use the 170mm Open division spring sets (Grams, 13-coil) in my 140mm Limited magazines instead of the Grams 11-coil 140mm kit. He said reliability would be drop-dead certain at 19 rounds and pretty darn good with 20 (depending on SV vs. STI mags). He was right. They've been like Energizer Bunnies.

I've been running those spring sets for a few years now with no ill effect. I'm guessing I might need to refresh the springs in a year or two.