Maximum Magazine Length

[Skywalker]

I was wondering about the USPSA rules for Limited division.

I read from Appendix US D7 of the green book that the max legal lenght is 140 mm for this division, and I acknowledge from Appendix F1 how to measure it.

Now my question: if you use a 140mm tube, what kind of base pad are you allowed to use? It looks like with that tube there is no room for a basepad.

Would you please enlighten me?

Thanks.

[TeamGE]

Skywalker,

The term "140 tube" is what the tube manufactures have named their product. The real measurement of the tube is 137mm, (+or- 1mm). You have 3 to 4mm to add in base pad length to fit the USPSA mag length guage at 141mm. All of my base pads are numbered as to the length they will add to the OAL of the tube, (2.5, 4, 6.5, and 11mm).

[Skywalker]

Thanks Beven,

that explains it.

I was playing with the idea of attending a match in the USA next year (at least I have the will...) and was also considering the possibility of buying at least one mag to keep up with USPSA capacity (my mags are SVI 126 mm tubes, IPSC box compliant 18-rounders, personally developed and tuned).

BUT, and this is the biggest problem, here in Italy we're not allowed to buy mags or other major firearms parts other than from armories where you can show your firearms license.

For this reason I was considering the idea of buying a tube and a pad from an on-line source in the USA, and then add spring and follower on my own.

I'll give your website a look.

[mai]

How about 170 mag for IPSC rule, can we set it up to 171mm or only 170mm is the limit.

mai

[Vince Pinto]

Hi Mai,

Sorry, there is no "+" tolerance. The maximum for IPSC is 170mm. See the diagram in Appendix F1.

[Skywalker]

mai,

as far as I know, there is no tolerance on IPSC mags measurements, i.e. 170 mm is maximum allowable lenght.

[mai]

But for standard box, we hvae the +, right?

mai

[Vince Pinto]

But for standard box, we hvae the +, right?

Yes, but that means the box can have "+1mm" dimensions, to allow a slight variance in construction of the box, but there is no "+" tolerance for magazines.

Hence, when conducting equipment checks, you measure the magazine first for compliance, then you insert the magazine into the gun, and then you place the gun inside the box, which can have +1mm dimensions.

[Dead Buff]

Hence, when conducting equipment checks, you measure the magazine first for compliance, then you insert the magazine into the gun, and then you place the gun inside the box, which can have +1mm dimensions.

This however does not mean that you can increase the dimensions of your gun by 1mm, because many boxes out there are very exact on the +0 tolerance....

[TeamGE]

The +or- 1mm quote I gave is the tolerances that are built into the mag tube themselves, without a base pad installed. Like IPSC, (with a box for gun and mag inserted) USPSA has a mag length guage, for Limited and Open mags. It will allow 141.25mm and 171.25mm to fit into it. IPSC does not allow the use of this guage, (for Open mags) so officals will be using the old fasion way of measuring, (a ruler) and the rule book does say 170mm. This is why I make a 2.5mm and 4mm base pad. You set up the mag for 171mm with a 4mm pad for USPSA, and then switch to a 2.5mm pad for IPSC. As little as it may seem, it does make a differance on loading that last round.

Skywalker,

Just to make it more confusing, your so called "126mm" tube, is only 120mm if you measure it the same way the book tells you to. Again, the manufactures of these tubes are not being consistant in their own measuring and labeling. Current mag tube lengths out there now, that fit the standard STI/SV grip are 120, 128, 137, and 167mm, with some other odd ball tubes out there that are no longer in production.