Are Lyman case length headspace gauges any good?

[Snake Pliskin]

Finally got my Lyman Case Length Headspace gauge in. I have been wanting to run some ammo I made through it to check that the Lee FL die was doing it's job properly as set to a .001" shoulder bump.

All of them gauged too big. Looking at the air gap between the steel rule and the Lyman tool.....I figured around .002" to .003" My ex-motorcycle mechanic eyes are still good....even though I cannot read or drive etc without glasses. I guess 23 years as master mechanic had some effect on me.

When I ran feeler gauges through the gap I got .0025"!

Okay so I have never trusted that Lee FL die, as discussed in another thread. But I decided to check out some random Hornady 120gr Match rounds from a couple boxes I have.......and a single round of American Eagle 140gr Match factory ammo that I have kept for reference. Here's where I got a surprise when I ran these in the Lyman measuring tool.

Hornady unfired factory cases sat proud by .0045" HUH?!!

The American Eagle was proud by .008" Double-HUH?!! Okay, in the "case" of the American Eagle case reading.....I had pulled the bullet using an RCBS Collet bullet puller to measure the bullet and the powder drop. Maybe....just maybe, the case got stretched just a little bit?

But all those factory Hornady bullets oversize?


How can this be? It has to be the tool is not accurate. When I first tried it (after cleaning it out with Gun Scrub or some other parts cleaner I have)......my reloads were hanging up in the gauge just a little bit above the case web as they went in....and it felt rough. I got out the old Optivisor and a light and I could see tiny little chips in the metal in the periphery of the tool bottom....a very sharp edge too. So I eased those up with 1000 grit and the cases went in nice and smooth afterwards. Okay just some hasty finishing after machining perhaps.

I also considered something might be rough or uneven by the shoulder area of the tool so I ran some 600grit wet-or-dry down there on a dowel and polished that area up a bit. It also helped things feel smoother, but neither action changed the readings.

So after all that yackety yak......

......has anyone heard of a Lyman Case Length Headspace gauge that is not manufactured to spec? Are these Lyman gauges essentially crap tools or have you had good results with yours?

Thanks.

 

[Rsadams]

Try and pick up a hornady headspace comparerter.. With the gauge anything's possible. I use the Wilson brand when I use them. The hornady tool kind makes them obsolete.. Good or checking function before going to the range.. Normally if they fit in the gauge correctly they will function..

 

[Snake Pliskin]

Yes I have all that and use it to set my bump..... .001".

The case gauge I'm using to verify the rounds will chamber.

 

[Snake Pliskin]

Meant to add.....I've always understood the case gauge to approximate SAAMI chamber specs. One would use it on the bench and then run a few in the rifle to verify.

Like for example .40 case bulge. Case bulge gets picked up right away.

 

[Ron Blain]

.....has anyone heard of a Lyman Case Length Headspace gauge that is not manufactured to spec? Are these Lyman gauges essentially crap tools or have you had good results with yours?

Personally while I have a few of this type gauge I am not a big fan of them. Just about everyone out there seems to make their own version, some seem OK while some are just plain inaccurate. That type aside for a moment lets take a look at The Hornady Cartridge Headspace Gauge is a good example. While you can measure a cartridge before and after and get an idea of how much the case grew the numbers on every one of them I have seen were far from accurate. Here is an example of what I am getting at:

OK, the gauge is zeroed. Next I will insert a known 1.630" actual chamber headspace gauge. I know this gauge to be accurate as before I retired I dragged all my gauges to work and had my guys in the labs check them. Believe me this gauge is accurate and it is a 1.630 Go Gauge. The calipers are also accurate. far more accurate than they need be for this experiment.

The gauge is reading 1.624" or -0.006" from a nominal 1.630". The problem with these things is the radius cut on the bushings. Measuring a cartridge before and after you can do the math and get a reasonably good change number but as to an actual dimension? I have yet to see one that gives real numbers.

Now as to the other style of a Go/NoGo cartridge length gauge? I have some Wilson and some old Forrester which are actually pretty good.

The only reason I know these gauges to be good and trust them is because I checked them using known chamber headspace gauges. Using the latter with a straight edge you can at least get an idea of a before and after on your cases which you can then use as an indicator of how much you are sizing the case in a die.

I do agree that the ultimate case gauge is one's individual chamber.

Just My Take....
Ron

 

[Snake Pliskin]

Thanks for that really informative and interesting reply Ron.

I totally understand the radius/bevel thingy on the Hornady L'NL inserts. I wonder if having them made by a machinist in stainless and leaving the edges sharp, would be the way to go?

As to the accuracy of the Lyman case gauge and your report.........

Are you saying then, that if I bought a Go/No Go gauge set for my 6.5CM (which I don't mind doing-kinda need it), from a known accurate manufacturer, say Pacific Tool & Gauge..... I could place that in the case gauge and check it for correct seating? However, are you also suggesting that even then I should still not expect a truly accurate result because I don't know the true accuracy of the Go gauge itself? Since I don't have lab guys to check it like you did.

Or would it still be the best way to check the accuracy of the Lyman case gauge?

Thank you again, thanks to all who have offered advice and suggestion.

 

[Ron Blain]

What I am saying is that if you have a known chamber headspace gauge with known accurate dimensions you can use it to verify many of the dimensions of your case gauges. That using a good chamber gauge I can check many of my other gauges. PTG is a good source, Clymer is another for chamber gauges. You may want to note that for example in my drawing, showing the Wilson gauges that I cannot check C.O.L. I can check gauges like the Hornady I pictured and once I know the deviation from nominal I can apply that in future measurements. Another family of gauges I like are the RCBS Precision Mic sets. Those have been overall pretty good. That's about it as I see it.

Having a good "known" can really be useful and a set of Go/NoGo chamber gauges are really not that costly. They can be used for several applications beyond gauging when cutting a chamber.

Ron

 

[Snake Pliskin]

I just measured the OAL of the Lyman gauge and it's shorter than SAAMI.

I understand this about it not being the best way perhaps to set headspace. I use the Hornady Headspace gauge and for .308 I have an RCBS Precision Mic as well. Between these I can dial in my shoulder bump and seating depth using the Hornady modified cases and the seating depth gauge.

The idea for me behind a case length headspace gauge is to do a penultimate check that the rounds should fit my chamber, before hitting the range. I just don't like cycling live ammo through my rifles in my garage anymore.

Thanks all!

 

[fguffey]

Finally got my Lyman Case Length Headspace gauge in. I have been wanting to run some ammo I made through it to check that the Lee FL die was doing it's job properly as set to a .001" shoulder bump.

Because you guys do not have shell holders that match your dies and you have no way to check the die I will say you are out of luck.

My cases do not have head space; as soon as I say that Lyman builds a case head space gage; I was reported to SAAMI, a very busy poster called SAAMI and reported/finked me out. He told them I said the case does not have head space, it did not matter to anyone but they agreed with me. The case does not have head space. And then there is 'bump'; I have bump presses, my bump presses are cam over presses. My cam over presses are called bump presses because the ram bumps at the top 'twice'.

F. Guffey

 

[Snake Pliskin]

Mr Guffey, no disrespect towards you but as much as I want to, I have a hard time understanding what you are saying.

My press is camming over, so it is a hard bump, yes?

I have the Redding competition shell holder set.....5 in .002" increments. Does that count?

Are you saying the Lyman case length headspace gauge does not have headspace or your sized cases? In what die? Could you please clarify that? I'm keen to know more about it.

Thanks!

 

[Ron Blain]

I just measured the OAL of the Lyman gauge and it's shorter than SAAMI.

I understand this about it not being the best way perhaps to set headspace. I use the Hornady Headspace gauge and for .308 I have an RCBS Precision Mic as well. Between these I can dial in my shoulder bump and seating depth using the Hornady modified cases and the seating depth gauge.

The idea for me behind a case length headspace gauge is to do a penultimate check that the rounds should fit my chamber, before hitting the range. I just don't like cycling live ammo through my rifles in my garage anymore.

Thanks all!

While I can certainly understand your concerns with cycling live rounds your chamber is likely the best case gauge you have. Possibly following resizing you could see how the newly sized case cycles. Granted you are less the bullet but you will know if the case head to shoulder datum is within limits for your chamber.

Ron

 

[Snake Pliskin]

That's how I have always done it in the past......cycling live rounds. Usually I would check several cases, one at a time and randomly after sizing, to make sure they would chamber. Then I would cycle random completed rounds as well and also at least one 10rd magazine, chamber and eject them all.

I was really hoping the case gauge would negate the live round portion of all that leaving only the final verification at the range.

I would never have thought a reputable company would sell a piece of measuring equipment that itself was not to spec. I still have to 100% verify this, but it's sure looking that way.

Thanks again Ron!

 

[Ron Blain]

My pleasure. There is a relatively new guy on the block, Sheridan Engineering has a case gauge out which they claim includes case diameter, most basic gauges do not. Not unusual to see where people post how their resized cases pass a gauge but won't chamber or their bolt is hard closing. Once you have verified things please do post the results, I would be curious.

Thanks
Ron

 

[Snake Pliskin]

Wow, I really like that slotted gauge! This is something I really need to have a visual on the shoulder etc. Simple genius!

Thanks for the heads up!