Pin gauge to check for loose primer pockets.

[jlow]

Thinking of getting these to check both large and small primer pockets. Currently using Wolf SRP and Tula LRP. Measured 13 of each twice with a Mito micrometer and came up with an:

SRP
Average = 0.1751”
ES = 0.00048”
Max = 0.1753”
Min = 0.1748”


LRP
Average = 0.2108”.
ES = 0.00065”
Max = 0.2112”
Min = 0.2106”

From looking at the web, I see min/max for primer pocket diameter:

SRP is 0.1730”/0.1745”

LRP is 0.2085”/0.2100”.

My question is what pin gauges size should I buy? Obviously at least one should be slightly smaller than the min diameter primer in survey but how much?

Should I buy specific ones or should I just buy a whole set that covers both?

Any specific brands and why?

FWIW, I know they make a “Swage Gage Primer Pocket Gauge” for checking both small and large primer pockets but I would much rather buy gauges specific for my primers.

 

[Ggmac]

I'd make my own go - no go set . 2 separate double ended gauges .

 

[ireload2]

The GO gauge design should be a full diameter pin about .0002 smaller than the minimum primer pocket diameter.

The proper design for the NO-GO is a double D shape at the maximum diameter of the primer pocket. An oversize primer pocket can be egg shaped or oval.
So the double D enables you to turn the gauge in 3 or 4 orientations if you find a pocket that is close to being out of tolerance. By turning the double D you can hunt for a localized out of tolerance condition.
The entire primer pocket does not have to be out of tolerance. If it is out of tolerance across any two points it is a reject.

Double D shape

http://www.cabletooling.co.uk/image/cache/data/61068c-400x400.jpg

You can buy .001 increment pins that are slightly oversize and polish them to the exact size you need.

You can buy Deltronic pins in .0001 increments and use the exact diameters as is.

To get a double D pin you may have to hand grind the flats on a round pin.

 

[jlow]

Ggmac – Unless it is hard to find and super expensive, I usually just buy it.

Ireload2 – very interesting! Thanks!

A few questions:

One is what is the purpose of a GO gauge? I realize that it is designed to weed out primer pockets that might be too small, but honestly I have never run across that situation although I presume that it is always possible. Regardless, my purpose here is to look for too big primer pockets and so this may be important but secondary.

For NO-GO gauge, so the double D allows you to find not just a too big primer pocket but one that is two big just in one orientation which I presume will still hold the primer but allow leakage on the too large side – I like this idea!

I started to ask about source but looks like you beat me to it!

 

[jlow]

So more thoughts on this....

As mentioned in the OP, I surveyed 13 primers of each size and there is as expected obvious variance. It would also be reasonable to assume that there are primers which would be smaller than the smallest one that I found/measured. What would be a reasonable undersize pin gauge I should get that would allow me to preclude letting in through a pocket that in fact is too big but yet not throw out ones that are in fact small enough?

I realize this is likely a statistics related question but I am looking for actual experience from people who may have done this.

BTW, I found the Deltronic pins and they sound super!

 

[eric32]

https://ballistictools.com/store/swage-gage-small-primer-pocket

Check these out

 

[jlow]

https://ballistictools.com/store/swage-gage-small-primer-pocket

Check these out

Yes, I mentioned these in my OP, trying to avoid them to find a tool that is more specific to my primers. The Russian primers are generally larger and so I imagine allow greater tolerance in enlarge primer holes, thus the reason for more specific tools.

 

[eric32]

My fault i dont know how i missed that

 

[ireload2]

If you have primers that are a very tight fit or suspected of being too tight the go gauge with determine if the primer pocket is tool small. I agree that you are not likely to ever need this tool but it should not cost more than about $3.00.
In my case I own a set of pins from .061 to .250 in .001 increments. The Chinese sets are about $80.
I also have a set from .251 to .500. I use these pins mostly to gauge the interior of FL sizing dies.

The Double D will find a primer pocket that is over size in one orientation. If you were to use a round pin, the round pin would not fit and you would think the primer pocket was intolerance 100%. However part of the primer pocket is out of tolerance and based on the standards should not be used.

Ireload2 – very interesting! Thanks!

A few questions:

One is what is the purpose of a GO gauge? I realize that it is designed to weed out primer pockets that might be too small, but honestly I have never run across that situation although I presume that it is always possible. Regardless, my purpose here is to look for too big primer pockets and so this may be important but secondary.

For NO-GO gauge, so the double D allows you to find not just a too big primer pocket but one that is two big just in one orientation which I presume will still hold the primer but allow leakage on the too large side – I like this idea!

I started to ask about source but looks like you beat me to it!

 

[Brians356]

Just spend $35 and buy a full set of gauges like this. Once you have them you'll discover myriad other uses for them, reloading related and otherwise. Believe me, you'll wonder how you managed without them. These are "class ZZ minus" meaning .0002" smaller than nominal size. If the link fails, just search Ebay for "M1 minus .061 .250".

http://m.ebay.com/itm/SHARS-190-PCS...N-GAGE-SET-MINUS-NEW-/350727698242?nav=SEARCH

Once you see how useful they are, you may want to spring for the next larger set, .251" to .500" (heavier and more expensive!)

PS

Another useful approach is to use a good carbide primer pocket uniformer (e.g. Sinclair) a gage of sorts.
-

 

[ireload2]

I think you will find that primers are somewhat elastic and flexible and will crush it fit an under size primer pocket.

Gauging a primer diameter has its own special problems. A 2 legged anvil will recsult in an obround or oval primer. This is easy to find with a micrometer.
A 3 legged anvil gives a trilobe primer and it is not readily measured with any tool with just 2 opposing surfaces.
If you want a max or min primer check you would need a ring gauge or maybe an ordinary Wilson or Redding neck sizing bushing of the right size.
If you can't get the right bushing it is easy enough to hone or lap one to size.

QUOTE="jlow, post: 36934536, member: 1282775"]So more thoughts on this....

As mentioned in the OP, I surveyed 13 primers of each size and there is as expected obvious variance. It would also be reasonable to assume that there are primers which would be smaller than the smallest one that I found/measured. What would be a reasonable undersize pin gauge I should get that would allow me to preclude letting in through a pocket that in fact is too big but yet not throw out ones that are in fact small enough?

I realize this is likely a statistics related question but I am looking for actual experience from people who may have done this.

BTW, I found the Deltronic pins and they sound super![/QUOTE]

 

[Ggmac]

The go no go is for dia and depth , one end to check dia and one for depth . That's the way I'd do it . While your at it you mite as well cut a teat to check for flash hole size .
I think I'd cut them full dia as a oval shaped primer is likely to leak .

 

[jlow]

Thanks guys!

So this brings up another question I have about those sets of pin that are advertised. As already mentioned, the pins are sized in increment of 1 thousands difference. So the question is would a 1 thousands difference be too coarse a jump between pins?

 

[Brians356]

Thanks guys!

So this brings up another question I have about those sets of pin that are advertised. As already mentioned, the pins are sized in increment of 1 thousands difference. So the question is would a 1 thousands difference be too coarse a jump between pins?

Fine enough to probe the range of min to max primer pocket dimensions, which spans 5 or 6 thousandths. You can get gages in .0005" and even .0001" increment, but you're opening a can of worms unnecessary for most purposes. By feeling the "wiggle" of a slightly loose gage fit, you can guesstimate roughly where it is in the middle.
-

 

[jlow]

Fine enough to probe the range of min to max primer pocket dimensions, which spans 5 or 6 thousandths. You can get gages in .0005" and even .0001" increment, but you're opening a can of worms unnecessary for most purposes. By feeling the "wiggle" of a slightly loose gage fit, you can guesstimate roughly where it is in the middle.
-

That’s just it though, if you look at the numbers I posted in the OP, range for SRP pocket spec is only 2 thousands and open that up by 1 thousands from 0.1745 to 0.1755 and none of the SRP I measured will hold (max dia 0.1753”). Also the diam range of the SRP I measured is only 0.00048”. So from that standpoint, if I started with the smallerst primer pocket, 3 thousands later it is already gone and that is the best circumstances. If I start with the largest pocket, 1 thousands and it is gone. So you can see this is why I am wondering if 1 thousands is a big jump.

 

[jimcasey01]

I just purchased a rifle with fire formed brass. The primers (only 5 or 6) I seated were the easiest to seat that I have ever had. I put a .1745 pin (actually .1747 by my measurements) pin into the primer pocket, a pretty easy insertion. I decided to get new brass. I rechecked the bolt face and there were no signs of gas cutting which I find remarkable. Call me chicken, but I will have more confidence in new brass.

PS I checked some of my normal brass that I use and the pin would not go in, even with pressure.

 

[Brians356]

That’s just it though, if you look at the numbers I posted in the OP, range for SRP pocket spec is only 2 thousands and open that up by 1 thousands from 0.1745 to 0.1755 and none of the SRP I measured will hold (max dia 0.1753”). Also the diam range of the SRP I measured is only 0.00048”. So from that standpoint, if I started with the smallerst primer pocket, 3 thousands later it is already gone and that is the best circumstances. If I start with the largest pocket, 1 thousands and it is gone. So you can see this is why I am wondering if 1 thousands is a big jump.

You're right, I missed that. Then you will have to buy a small set of .0005" or .0001" gages in the range you need, they're out there. Or you can get an adjustable hole gage of the right size.
-

 

[jepp2]

I hope it works out for you. It didn't for me. I have 2 full sets of pin gages (0.001" increments). I had some once fired LC 223 brass fired under hot weather with some loose pockets. Pin gages didn't work at all for me. The closest I came was using the stud base from my RCBS primer pocket swager (before actually swaging them).

But even that wasn't a very good check. So I just processed all the brass, and when I started priming, any that primed easy I would separate those and knock the primer back out and toss the brass. This worked well for me.

There is a commercial swage gauge made by Uniquetek. Here is the link: http://www.uniquetek.com/product/T1521

 

[Lou Murdica]

Leave your primer pockets alone.
I don't clean them ,I don't do nothing to them. If the primer hole is to tight just Debur the front of it just a tiny bit.
Otherwise leave it alone . Doing anything to your primer pockets will not do anything for accuracy. But you can definitely damages It.

 

[jlow]

I hope it works out for you. It didn't for me. I have 2 full sets of pin gages (0.001" increments). I had some once fired LC 223 brass fired under hot weather with some loose pockets. Pin gages didn't work at all for me. The closest I came was using the stud base from my RCBS primer pocket swager (before actually swaging them).

But even that wasn't a very good check. So I just processed all the brass, and when I started priming, any that primed easy I would separate those and knock the primer back out and toss the brass. This worked well for me.

There is a commercial swage gauge made by Uniquetek. Here is the link: http://www.uniquetek.com/product/T1521

I am interested in hearing how it did not work out for you and why? You have loose pockets and pin gages and are you saying a pin gauge that says the pocket is tight was in fact lose? Or visa versa?

Unfortunately, we already talked about the swage gauge.

One thing we have not touched on of course is the deformability of the primers itself. Ireload2 touched on it a bit when he described how a two vs. a three legged anvil affects the shape/size of the primer. I imagine that seating the primer will produce significantly greater force and deforming - well at least I myself have seen many swashed primers...