Min or Max Saami Spec Reamers

[J E Custom]

This has been an interesting debate and the main reason that I posted was to prevent the original
poster from getting a reamer that "could" cause problems if he did not know the effects of subtle
changes in the SAMMI dimensions.

I hear horror stories all the time about a chamber reamer that has been modified without the
owner understanding what the change may cause if not dealt with.

An experienced shooter/re loader may have a specific reason to change the SAMMI dimensions
and knows how to deal with the change.

As a smith I do not recomend any thing other than a SAMMI spec reamer unless the person
understands exactly what he is doing (Cause and effect) and the pluses and minuses that come
with changes to the standard and knows how to deal with them.

It does not take a special reamer to build an accurate rifle.

J E CUSTOM

 

[EddieHarren]

"It does not take a special reamer to build an accurate rifle" True.

 

[gunaddict]

Any other thoughts on how much freebore for the ultramags when ordering a reamer?

 

[ken snyder]

minnimum and maximum dimensions exist for both chamber and cartridges they are maximum manufactureing deviation tolerances. anything within those tolerances is a standardized cartridge or chamber In my earlier threads my objection was and still is the use of the words min spec. or max spec. when we are actually refering to modified cartridges. I am certain most are aware of the difficulties Smitty's have with the general public and not at all interested in explaining poor nomenclature. For many of us it is a liability issue or at the very least a reputation issue as well.

 

[milanuk]

Just to clarify... because this subject is of considerable interest to me on another front....

There is a SAAMI spec for the chamber dimensions, with a plus tolerance.

There is a SAAMI spec for cartridge dimensions, with a minus tolerance.

The idea is that (factory) ammunition that is at or below the maximum SAAMI cartridge dimensions should still pass into and out of any chamber that is at or above the minimum SAAMI chamber dimensions.

Yes/No/Maybe?

As a result, these 'minimum SAAMI spec' reamers are not truly 'SAAMI spec', but custom ground reamers that are at exactly the minimum chamber dimensions plus/minus nothing, correct? Or are they cut to maximum SAAMI cartridge spec? As an example, .308 Win min SAAMI chamber spec is listed as .344-346 at the neck (tapered), +0.002, but the cartridge spec is listed as a *maximum* of .343 (no taper)... which is a lot closer to what I see in some 'match' chambers - they pretty much start at .343 and go on down - .342, .341, etc.

 

[azgutpile]

Where does a"Match Grade" reamer fall into all of this?

 

[ken snyder]

This is a very interesting thread and perhaps one that we are shareing the same general thought. It is not possible to manufacture anything exact. all reams have unimportant differences. Unless specified, a tool grinder will not manufacture a ream that will cause him headache because it is too small. A Resizeing die manufacturer will not make dies that do not re-size far enough, because neither receive complaints about a cartridge that will chamber. any thing other than that is a custom modification available only by request. How ever military and police have strange requirements including fluted chambers. ( I leave their strange world totally alone). Even at that, the small differences in same designation dimensions is tremendously out weighed by the accuracy of the lathe being used to do the chambering and the skill of the operator. A poor set-up will never make a chamber smaller than the ream it will always make a hole larger than it. Shoddy examples can make massively oversized chambers with the best ream that any man can make.

 

[Edd]

Where does a"Match Grade" reamer fall into all of this?

"Match Grade" is a term that most likely falls smack dab in the middle of the marketing department. I would only want a match grade reamer if I had a match grade barrel and was shooting match grade ammo that had been loaded with match grade bullets in a rifle that had been built with match grade tolerances. Where is George Carlin when you need him.

 

[shortgrass]

Match Grade and Custom drop-in,,,,,,,,,!!!!!!! Ken Snyder's got it right on manufacturing tolerances, nothing is exact. Neck diameter is about all most gunsmiths can measure on a reamer, most don't have a 'shadow graph' to be able to measure anywhere on the tapers. The finished chamber tells the story. I have had a couple of 'specials' made. On those Manson works within +.0005. I think most SAAMI spec reamers made that are for the custom trade are on the 'minimum' side.

 

[ken snyder]

kind of funny now that shortgrass mentioned floating a ream, personally I think they are a cats meow, with very good results. I know some guys that would rather run one of the set-true style chucks and they get real good results as well. The funny part is the "which end of the barrel goes in the chuck" debate - well I think its funny !

 

[shortgrass]

'Shadow graph' is the slang name for an Optical Comparator, which is a measuring device. It has nothing to do with chucks or holders.

 

[ken snyder]

Sorry about that, thought you mentioned "manson" floating ream holders. Maybe they are Mason I'll have to look! The first time I used a shadow graph was in 1985. Two different kinds 1 a comparator with a calibration grid and the other a profile scope that had interchangeable templates. Now days most of them are sitting in the corner of a grinding shop covered with coffee cups and dust. The new griniding equipment has a resolution of up to .000005, with their own measuring sensors. pretty much makes the old stuff obsolete. but sure was fine back in its day.

 

[shortgrass]

Manson makes a floating holder, but, his company also makes tools and does a da^% fine job of it, too. I've tried most all the tool makers we hear about on the web and some, very few have heard of, and I'll choose a Dave Manson reamer over most. His turn around times are very good and customer service is second to none. Tools from him are right the first time. As for 'floating holders', yes , I use one. Mine is unique to my lathe, as it was made after a couple of days of leveling and alinement and then all work possible was done buy feeding the work, held in the tail stock, into the tools held in the 4 jaw chuck. The same process used by machine manufactueres when they make tool holders for their machines (only they usually use collets). That tool holder becomes 'dedicated' to that particular place on that particular machine and may not be accurate if used on another machine. It makes it very easy to make a chamber the same size as the reamer. I use a 'floating' holder instead of a 'pusher' because my feed rates are higher than most use, made possible by, my home made, pressure flush coolant system. My 'shadow graph' has a cover over it, but not coffee cups and dust!

 

[ken snyder]

shortgrass I hear you loud and clear. I used to make my living by being a mech-elect for companys that built the equipment that many of us are using today. Your building of your own specialized equipment built specifically for your machine is absolutely the best way to get a job done correctly. The new super equipment is fantastic but whenever I ask my son-inlaw how much it would cost to manufacture parts with the tolerances I want, I don't know whether to laugh or tell my daughter to get a divorce. ( just kidding he's an outstanding young man) Someday guys like us will be history.
But for now we rule and the rest can only slobber on themselves.