A review of the Saami drawing of a 2-3/4" chamber (pg18)

The only way to get a true measurement is to make a plug at .798ø, drop it in and obtain the measurement. The plug end that's inserted into the chamber must have a dead sharp edge and the diameter (.798) is a basic dimension due to the fact all dims are at maximum material condition..meaning, no tolerance at all for the plug ø. The Saami spec was issued May 1979 & was revised July 2015 however it doesn't say what revision it is. (e.g., A,B,C, etc). There's also a note that clearly states "chamber lengths (per the standard) have been lengthened. Without a review of all revisions since 1979, that indicates the 'official' lengths increased in 2015. Therefore, since the PR's were made long before the revision...you have 3" chambers in a SCC despite the fact they're marked 2-3/4".

Ed Muderlak often stated: The investigation continues . . .
 

Thank you Scot for helping to bring some clarity to the drawings.

In regards to Victor's 12-ga, 26" gun's 3" chamber length . . . I recall a thread or two in this forum where a poster that was quite close to the development of the SSS intimated or suggested that all 28" 12 and 20-ga. Repro barrels were factory chambered for 3" shells. Is there the possibility that all 12-ga. Repro barrels, 26", 28" & 30" lengths, have 3" chambers? I know that there are 20 and 28-ga. 26" Repros which were not chambered for 3" shells, but I have never owned a 12-ga. 26" Repro, nor have I measured, nor do I recall anyone posting - other than Victor - that their 26" 12-ga. Repro has 3" chambers despite them having only the 2 3/4" stampings.

Wouldn't it be great if owners of 12-ga. 26" Repros would weigh in with their findings?

You're welcome Greg. In the quick review I did make a bit of an overstatement stating in part, "the only way to obtain a true measurement". That should read the only practical way to..

Frankly, I think the topic's a silly hang-up on technical mumbo-jumbo to tell you the truth..

I have a 12 ga 2 barrel set. Both 26" and 28" are stamped 2.75 & 3" shells. In fact they are 3" chambers on both sets.

IMHO, the sale favored the buyer & I hope someone here got it.

Also, let me clarify what might have come across a bit snarky (unintentionally) - when I say the discussion's silly..I mean that it doesn't require an overabundance of hyper-technical dialogue. It's simple..drop a scale into the chamber, make sure it's edge is pushed down firmly against the chamber wall and take it to the forcing cone. If it's basically 3" to the forcing cone, have at it with all the 3" shells you wish to fire. Or, limit your ammo choice to 2-3/4" and never, ever worry about it. There's arguably an excessive margin of safety now built into the most current standard and I'd guess that likely has more to do with attorney's than anything else. That's not to say it's not interesting and thanks to Johnny for sharing the info, along with his perspective that isn't exactly right but isn't exactly wrong either. Now Johnny will show up and slap a revision on us from 1982 that shows chamber lengths were increased back then and we've all got it wrong..:rotf:

I've not checked my 12ga, but I will b/c I can't recall how it's marked. I think I recall John Allen sharing the factory all but insisted on multiples of 25 when accepting an order so their internal numbers made sense for a production run. That fact would likely explain inconsistencies in chamber length across the 12ga's, I would think, no?