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140mm tubes and pads


Skywalker

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Hi all,

I just received a Brazos tuned 140mm .40" tube, and a couple of Grams basepads (a 2.5 and a 4mm).

My question now is: according to your knowledge/experience, what will be the USPSA legal setup for such a mag in Limited Division?

Is a Grams Engineering pad legal on a 140mm tube, or does it anyway exceed the max allowed lenght of the mag?

If it is allowed, what is the max lenght of the Grams pads that is still legal? 2.5mm? 4mm?

Thanks for answers, I'm a newbie when it comes to USPSA rules.

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Thanks Vince,

I read it.

But since I read on these forums that USPSA uses sort of a box to verify mag compliance with divisional requirements, I prefer to get feedback from "field users" instead of measuring with a caliper the OAL of the mag+pad (which, BTW, is quite variable depending on how you place the caliper on the spots showed in figure in Appendix F1: I got different measurements differing at least for 1mm depending on how and where the caliber was placed... :unsure: ).

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Thanks Flex,

I'll try and contact Beven if I don't get enough feedback from forum members.

I was wondering because I just finished to set up the mag and discovered that, applying the internals I use for my IPSC mags to a 140mm tube and 4mm Grams pad, I can get a .40" 21-rounder which is also an easy relaodable 20... :blink::) , while with the 2.5mm pad capacity gets downgraded by 1 round.

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Yeah,

I did and I recall it (I took my alzheimer pills this morning...did I? :unsure::D ).

But I am looking for specific feedback on specific components, rather than the general explanation I requested a month ago.

I have also searched the forums and got quite a few general indications that a 140mm tube, fitted with a Grams 4mm pad should fit (even if very tight) in the mag gauge, but, as I said before, I was looking for specific feedback on the components... ;)

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Luca,

The USPSA gauge is actually 141.25 mm. Using an STI tube and a Grams 2.5 pad will pretty much in every case fit the gauge without modification to the tube. With the 4mm pad almost every tube has to be modified to fit the gauge. Material usually needs to be taken off at the top rear of the lips as viewed from the rear. The USPSA gauge has an upward angled piece where the measurement is taken at the top of the mags.

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It's a little tricky to answer your question. 140 mm mags don't always measure what they are supposed to. Over the last 15 or so years STI and SV have had a couple different dies for the magazines. My understanding is that the only way to get 21 in a 40 mag is to use one of the original STI 140 mm magazines. Beven could probably answer better, but all my Beven 140 mm mags only hold 20.

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That's the one Luca. I like to use Beven's internals because I know the mags will be reliable, once you start cutting coils and using different springs/followers you may be able to get one more round but reliability suffers.

I'll pass on your kind words to Ingi.

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The 2.5mm pad is for those that just want to slap the pad on and go. It will be under 140mm. The 4mm pad is for mags that have been tuned (at least by Beven). They both allow for 20 rounds with his internals, but the 4mm is much easier to reload to with 20 in the mag. HTH. :)

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300lb'er got the end results right, Mr. Brazos explained the mechanics correctly, and Lawman got the 21 round story almost right. In the old days, STI made a "Competition Mag tube" that measures 128mm long. This tube is not made today. With a custom made base pad, and alot of tuning and polishing, I can make them hold 21 rounds. Thanks guys for jumping on the info so fast. I hope Skywalker got his question answered.

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In the old days, STI made a "Competition Mag tube" that measures 128mm long. This tube is not made today. With a costom made base pad, and alot of tuning and polishing, I can make them hold 21 rounds.

Hmm.. I probably have a bunch of those and don't even know it. Now taking bids! :D

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I bought both the 2.5 and the 4mm. The 2.5 made it easily into the gauge. (I have a gauge at home) If you want to go with the 4mm, it will fit with only minor modifications to the back of the feed lips as Bob pointed out. I only needed about 2 light short swipes with a file to get it to fit. Polish it back up and you're ready to go. However, I wouldn't do it without the gauge. If you aren't going to get the tube tuned, just get the 2.5 and be done with it. I saw some of Beven's work last weekend... It's worth the money.

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There are also some 21 round custom tubes floating around. Just like I have a 19 rounder that fits in the box for IPSC Standard, my buddy has two 140mm compliant 21 rounders for when he goes up to the US Nats.

Tubes seem to be custom made, and there appears to be more to the follower and spring than anything else.

Just FYI

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Does anyone have time to photograph the 2mm, 4mm, 6.5 and 11mm together...just curious of what they look like in relation to each other...

thanks..

Never mind....figured out where the difference are between the 2mm and the 4mm pad are...

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Looks like the one I have..from EGW..which I am told they make the official one for USPSA and are allowed to sell replicas of that to the public..

It is marked 141.5mm on one side and 171.5mm on the other..

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Thanks everybody for replies,

I think I have all the info I was looking for.

I'd be glad to be able to have either Beven or Bob doing their magic on mags, but sadly if I buy complete mags anywhere else than in local (italian) gunshops I'd be legally prosecuted, due to local laws that consider mags as main part of a firearm (like frame, barrel, slide), thus I have to buy them from authorized dealers showing my carry/sporting license... :(

I can however buy single components (as tube and pads) and assemble my own mags (provided I have the police add this mag to my firearms declaration)... :)

For this reason I'm resorting to tuning my own mags... ;)

Vince,

as eerw pointed out, the mag gauge manufactured by EGW (see here) is made for USPSA tolerances, thus it's 141.25 on one side and 171.25 on the other:

"The gauge is CNC machined out of aluminum and is anodized black.  It measures both 140mm (141.25mm) and 170mm (171.25mm) length magazines. The gauge fits all known combinations of magazines and basepads."

But I guess it would be a nice addiction to the IPSC shop if IPSC could manage to make an official IPSC 170mm compliant version... ;)

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