Sammi specs

[Snuby642]

I went to sammi . Org and downloaded thier specs..
Over half of them are illegable. I could read the 308 but not 223 or 300blk well enough to use.
It downloaded on a pdf format and is not good quality.

Is there some place I can get better.

Working on shoulder bumps etc.

 

[antithesis]

Knock yourself out...

https://loaddata.com/Cartridge/223-Remington-556mm/2535

https://loaddata.com/Cartridge/300-Whisper-300-AAC-Blackout-300-Blackout/1652

Just plug in what you are looking for: https://loaddata.com/Search

 

[Snuby642]

Both of those drawings were missing the shoulder to datum measurement I need.
I need the chamber measurements as well.

 

[Snuby642]

For an example in 308 chamber is 1.630-1.640 @ 0.400 datum.
Case is 1.634-1.627 @ shoulder datum.
New factory loads are running 1.627 exactly.

My first fired magteck cbc is running 1.630
And my fc gmm is running 1.628 - 1.6285

I dont think I have filled my chamber on the first firing.
Now that I have a neck sizing die I should be able to find it.

The 223 and 300blk are fls dies and certain I am over working the brass.
That is why I need those measurements but can not read them from
the sammi poor quality pdf.

 

[antithesis]

For the chamber, you need the reamer dimensions. There are at least several different reamers for each with different tolerances, different dimensions. Some tight, some loose, some long neck, neck turn, no neck turn, etc.

 

[Snuby642]

So I have downloaded saami specs on my phone, tablet and full sized computer.
The 223 and 300blk specs are illedgable.

I need the shoulder datum and min max dimensions for chamber and cartridge.

The pdf saami posts is bad quality even when magnified.

Does anyone know where I can get a ledgabale copy or the dimensions I need?

 

[cornhusker86]

 

[cornhusker86]

 

[Snuby642]

@cornhusker86
Thank you very much!
Those are clear enough to not need my glasses.

It came to our attention that several dies we have were setting the shoulders back excessively,
when set per manufacturer instructions.

Untill we got our head space comparitor we had no idea it was possible.

We had been using case gages and luckily are still alive.

Also did not know till we started neck sizing that fire formed brass may well not happen
on the first fireing. All the threads seem to imply fire once and bump back 0.002 - 0.004.

In the case of our 308 brass it put us below saami min using fls die.

Suprised at some of the accuracy we got with our bad practices.

Maybe a warning on case Guage would be nice, and the first fired brass thing.
I doubt I'm the only one to have done this.

Thanks for the help!

 

[MtnCreek]

I don't know why saami spec matters for your loads in your rifle.

 

[Snuby642]

I like to keep within known standards for piece of mind.

The specs just like a case gage, headspace comparitor and bullet comparitor
is just another tool.

After reading saami spec for 308 for example noticed that all of our new factory ammo
was at minumum.
Cbc brass grew 0.003 "to saami min chamber" and fc gmm only grew 0.002 at the most.
That was first fired and reasonably sure not the max for my chamber at all.

I plan on shooting neck sized brass till it drags on closing then bumping it back.

I also figure any chamber sold as a standard barrel not match grade has been sent out at
maximum saami spec, probably most factory set closer to max on the chamber.

So far it appears first fired is not fire formed enough.

 

[MtnCreek]

FWIW. Use a FL die set to not touch the shoulder will likely increase cartridge headspace.

 

[Snuby642]

Luckily on the 308 we have a neck die, when I find my chamber I will set the fls die.
I have not done all the measurement on the 300blk or 223 yet wanted specs to compare.

Since I dont have neck dies for those will try backing off 0.002 at a time and checking in chambers before loading and stay in spec along the way.

I did not know store ammo was 0.003 below chamber minumum, in a chamber
with +/- 0.010 tolerance.

The 300blk is used in 2 "identical" guns, will now segragate and find tighest chamber.

The 223, a bigger problem at last count 7 different barrels, but I may at least try min
chamber spec instead of min ammo spec. Maybe get rid of 0.003 slop or so?

 

[Snuby642]

Today was an eye opener on chambers and rounds with the headspace comparitor.

Factory 223 so far under chamber minumum I measured several brands over and over
thinking I made a mistake.
No it's just that short, a lot of first fired range brass did not even make min spec. WTF
Will have to get a neck die to get them to chamber max.

Same sad story on 300blk but not as bad.
That being said only getting about 0.002 shoulder movement at best out of subs.
May get a neck die for them?

In all cases "calibers" barely getting to min chamber spec on first fired if at all.

Not sure the best road to get to my chamber max for the fls dies -0.002.

Suggestions welcome, stupidity bashing expected.

 

[Supersubes]

Use FL dies, and set them up for your chamber. If the case isnt expanding fully on the first firing, size it without pushing the shoulder back, and shoot it again.

 

[MtnCreek]

What are you basing 'min spec' on?

 

[Snuby642]

The Sami chamber drawings.
All I have read have 0.010 min-max size on the shoulder dimension .

The cartridge mostly has dimension max -0.007 normally falling 0.003 below chamber minimum.

I measured new 223 rounds up to
0.006 below chamber min.
Factory rounds for 308 and 300blk were running -0.003 below.

First fired were at chamber min except many 223 was still short.

I have read many posts on several forums "fire once and bump back 0.002".
This will not fill your chamber with the possible exception of a match chamber.

I have to reset all my dies.

 

[Supersubes]

The only way I see you consistently getting short fired brass is if you’re consistently shooting at very low pressures. Bumping .002 is a good method, but not if your brass is already short, as you noted.

Also, the .010 tolerance noted on the saami drawings is the extreme. Only time you’ll find a gun that has a chamber that long will likely be a very haggard old military rifle. Modern stuff almost always falls in a .004” window between a Go and a No-go gauge. The cartridges obviously must be on the short side of the minimum so the tolerances won’t bump each other.

 

[MtnCreek]

What kills your 223 brass?

What kills mine:
The grass / leaves eat it.
Primer pockets loosen.
Split neck or lose of neck tension if loaded many, many times w/o annealing.

Case head separation is not on my list. I size to a generic drop in case gauge (dillon) all loaded to feed in every AR I own and so far, every other AR I've shot them through. I just wonder if you're seeking a solution to a problem that you don't have.

 

[Snuby642]

Many of my measurements were on range pickup brass to get some perspective.

So if I check go nogo dims that will be closer to reality? Makes better sense.
I have to get some un bumped second fired brass to get close I think.

I know my 223 factory rounds were loaded to 3200 fps.

Just guessing here but seems factory loads are set to give 2 firings before needing bumped?

 

[MtnCreek]

Factory is set to fire in any in spec chamber with no regard for the brass ever being used again.

The range pickup doesnt add any valuable info IMO. Was it fired through a bolt gun or way over gassed carbine with near max headspace? We don't know.

Just for fun, measure a un-sized case fired in your rifle. Turn your full length die out one turn from current setting. Size that case a re-measure. You'll probably find that it is now longer from head to shoulder.

 

[Supersubes]

Many of my measurements were on range pickup brass to get some perspective.

So if I check go nogo dims that will be closer to reality? Makes better sense.
I have to get some un bumped second fired brass to get close I think.

I know my 223 factory rounds were loaded to 3200 fps.

Just guessing here but seems factory loads are set to give 2 firings before needing bumped?

They’re only “set” to be small enough to chamber in any so chambered rifle, without interference. A full pressure load will absolutely, 100%, fill the chamber. A lower pressure load may not.

Forget about the saami drawings. Your chamber, your dies, and your brass are all that matter.

3200 fps...with what bullet, is what barrel length? With a 40gr in a 26” barrel, that would be a creampuff load. In an 18” barrel with 55’s. That’s moving. Doesn’t change what I said above.


What Mtncreek said. Range pickups mean nothing whatsoever. I wouldn’t pick it up to begin with, let alone try to glean info from them.

 

[spife7980]

Since youre all wet over the "saami spec" and how it matches up to your readings:
How are you justifying the saami spec to your equipment?
Do you have a go gauge that you are using to measure and set as a 0 reference point and then measuring your brass from that? If notthen how can you expect your readings to be correct to absolute? A comparator is relative, its good for your set of tools and equipment, it doesnt transfer to anyone else or to any other spec. Its a before/after tool, not a foralltimeeverywhere tool.



Going to steal some pictures from this write up by Ron Blain on AS


He has the actual headsapce gauges in known lengths.

Zero the comparator

Measure the known dimension (minimum headspace gauge). We know the gauge is 1.630", the comparator reads 1.624- IE the provided measurement from the calipers is short .006" of the known absolute measurement. This is why the bushings on the calipers are called a comparator and not a gauge. They are relative measurements, not absolute measurements.

So that .006" is almost all of your stated tolerance above if you dont take into account the tolerance stacking.



Virgin bras measures 1.623, thats only .001 less than the above measurement on an actual gauge. SO this round is .001 short of minimum chamber, in other words the virgin brass is perfect to fit in any chamber that is within spec.

++



Now for a fired case, when fired it has grown by .004" to 1.627 relative. If we were to add the .006 difference in gauge and caliper readout the brass is now actually 1.633. In either case the fired brass is 003 over minimum.

I wish he would have continued this exercise and measured his chamber to see how short of maximum he really was for case growth reasons since he has the gauges to do so in .001 increments. But thats not the purpose of his post, his purpose was to show that the actual measurements dont match the comparators caliper reading. And as such taking your comparators measurements and comparing them to saami spec is meaningless unless you have a actual known constant on which you can measure to compare between the two.



Im betting that the once fired is a lot close to maximum chamber size than you think it is (especially from a 223 doing 3200 fps). And reading off of range brass from God knows how many different chamber and brass combinations isnt a reliable method to go off. If youre going to go down this road of nitpicking to spec then you really need to know what you are doing and what your tools are actually telling you. And you cant to that with brass.

 

[Supersubes]

Now you done it Snuby. Spife is here with the arts and crafts, and a bunch of good points.

 

[Snuby642]

Ok so after checking go/no go
1.630-1.634 I feel better about my results.

My mag tec CBC 150g fired brass is measuring 1.6300-1.6305 from new at 1.627
The fcgmm is averaging 1.628 fired from 1.627 new, wimpy.

So you believe my chamber is 1.6305?
I have neck sized some of that but holding off on loading gun is in shop for scope mounting problems.

The range 223 was just a reference for our brass, those notes are across town.

Happy to see @spife7980 help you guys smack me into shape.

I need it.

 

[Snuby642]

I think it was spife that got me to quit using case gauge as my headspace tool. Lol

 

[Snuby642]

I had no idea my comparitor was also not accurate. ARG

I worked in an environment where every caliper and gauge were checked by meteorology services for 34 years.

And besides I'm German.

 

[Supersubes]

I had no idea my comparitor was also not accurate. ARG

I worked in an environment where every caliper and gauge were checked by meteorology services for 34 years.

And besides I'm German.

If you want a perfect set of comparators, in each datum size, so your numbers match a set of prints, you can have it. It’ll just be $400, not $40.

Many have come to the same conclusion that case gauges are less than ideal.

 

[EnjoyTheWilderness]

Regarding the readability of the SAAMI C&C drawings PDF. Particularly the one for rifle. Oddly enough I looked at that document this weekend and felt the resolution of the drawings was worse than I ever remembered them being in the past. It is truly difficult to read some values. I feel confident it wasn't always this way. I then stumble into this thread today.

As of right now... the Rifle document is no longer available on the SAAMI site. You get a 404 error. It was available earlier today. Others (such as Rimfire) are available and for those, the drawings are readable. While the document information may not have changed, I wonder if in the recent past, they had uploaded a version that had screwed up the drawing resolution. I am curious to see if once the document is available again if it might be an improved version or the same one as before.

And thanks for the link to the AS article and photo that show using go/no go gauges with the comparator tool. I don't know why I haven't thought of doing that before. That article is worth a read including the later photos of someone who made their own set of bushings, but of high enough quality that (if I read it correctly) he is able to actually generate "absolute" values and not just "comparative" values. A 1.630" 308 go gauge measures as... 1.630"

 

[Snuby642]

Yes I was quite surprised as to the lack of quality trying to read the Sami specs.

I was equally suprised my measurement tools suck.

I wanted to set my fls dies at a known standard within Saami and let them rock but not at bare minimum ammo specs.

I guess for 40 bucks I may as well cram a crayon in the chamber and measure with a 6 inch scale.

 

[MtnCreek]

You can get accurate and repeatable results with a good caliper and sinclair or harnady tool. You just have to accept that your measurements are not comparable with saami spec'ed measurements.

 

[Snuby642]

You ever want to piss off a German sit him in the corner with a tool that is not perfect.

 

[AIAW]

Since youre all wet over the "saami spec" and how it matches up to your readings:

SAAMI makes most people moist. CIP - time for a new set of panties.

 

[MtnCreek]

You ever want to piss off a German sit him in the corner with a tool that is not perfect.

Are you sure you're not polish?

 

[EnjoyTheWilderness]

So to come full circle on this. Saami has posted new PDF files for rifle and pistol cartridges and the diagrams are back to how I remember them. The diagrams are now very legible.

 

[SpeedyR]

glad to hear that. I had downloaded a lot of caliber SAAMI spec charts a few years ago and was going to offer up my copies if I happened to have ones that folks needed. I need to go back and get some of the current "caliber craze" calibers for reference, so nice to hear they might be updated!

 

[Snuby642]

Ok so I looked up go/nogo and found some brass that was 1.464 /1.4635 closed fine.
Added 1 layer tape closed fine.
Added 2 layer tape 1.467 closed with resistance.
Since all my ar's have nato chambers fine.

I plan on raising my die till I get 1.460 right now it is 3 1/2 -4 shorter than that and matches a lot of factory stuff.

I dont think that much slop is necessary?