Opinions about measuring Seating depth on CF rifle

[Rustystud]

I have used the Hornady OAL bullet seating depth gauge (formerly the Stoney point gauge)that uses your bullet and a drilled and threaded case along with digital caliper. This usually requires multiple measurings and averaging the results.

I am looking at purchasing the Sinclair model (stainless steel) that uses your bullet, and case along with a bushing and two locking collars. It uses measurements off the bullet in combination with the distance from the case head.

Do you have a prefrence of one system over the other?

Nat Lambeth

 

[Greg110]

I prefer the Sinclair. It's still not perfect, but I feel it is an improvement over the Stoney Point.

 

[4xforfun]

I know I am going to shoot myself in the foot here, but here it goes.

I actually have both, used both, and don't anymore.

My process, as primitive as it is, seems to work for me, simply because when I used the above mentioned tools I get many different readings.....maybe because my measuring tools have way to many numbers to the right of the decimal point. :-[

My process...start with sorted bullets....grab a bunch in one batch ( I sort to .001 bearing serface on boat tail bullets with Shehanes setup) and load up a few long. Take your bolt apart and with the bare bolt installed, try and close the bolt on a long bullet. DO NOT FORCE IT!!! If the bolt does not close, set that round aside, grab another bullet, seat it a little deeper and try and chamber it. Doesn't fit, set it aside and repeat until the bolt closes with just a very little help....I like my bolts to close at least 1/2 way with no help. Never use the same shell twice, because after I get to this point I inspect the engraving of the lands on the bullet to see the shape of the land marks...I like to see a square mark on a VLD bullet. I suppose that would be different if you have a 3 groove or a six grove....I have mostly 5 groove tubes. From what I have figured that square = about a twenty thou jam, which is where I start all of my load development.

After you find the OAL, re-run the long rounds through the seater.

This is my process, so I don't need a flame job if you figure that this process will end up with a 30 tho jam or a five tho jam...just my ,02. This is as deep as I will ever seat a bulet.

I just re read my post....I use plenty of neck tension with this process.....if you use too light of neck tention, the bullet will push into the case before you get square marks.

I just re-re read my post...I suppose it is not nessesary to use sorted bullets for this process...any deviation with bullt length will just be stuffed deeper in the case...should make no difference.

 

[tenring]

Nat - I stopped using the Hornady because it was not very accurate. Went back to using something I bought about 35 years ago. Do not remember where I got it, and there is no i.d. on it. It consists of two steel cylinders about 1" diameter and 1.5" long with a hole about .250" drilled thru the center of each. Each tube has a threaded hole and matching thumb screw near the center. Insert both tubes on a cleaning rod. With bolt in rifle, slide cleaning rod toward breech until contact is made with the bolt face. Tighten the rear thumb screw. Then, remove bolt and drop a bullet as far as it will go into the chamber. Slide the cleaning rod in until it touches the bullet tip. Insert a small dowel into the boltway, until it contacts base of the bullet. Do not jam the bullet. With tip of cleaning rod against the meplat, set the second tube against the muzzle and tighten it down. Remove cleaning rod and with caliper, measure between the cylinders for exact reading.

After I have written down this figure, I load a dummy case with the same bullet to get case head to ogive distance. ADJUST THE SEATER MIC TOP TO RAISE OR LOWER THE OAL and yer done.

 

[PREMOD70]

I never had any luck with using a bullet to measure throat leade but struck gold using the steel spud found in the RCBS precision micrometer. I unscrew the spud off their throat measuring device, use it in a slightly tensioned cartridge case and for me the measurement is very consistant when measured with their micrometer. The nice thing is once the measurement has been arrived at the micrometer will measure any bullet seating without having to remeasure the leade other than the occasional check for throat erosion.

 

[in2deep]

A trick that somebody told me was to put a cleaning rod down the muzzle with your other hand and keep it in contact with the bullet as you push/pull the seating tool which helps me get more consistent results and stops the bullet from sticking in the barrel in jam.
I think most of the discrepancy with these tools comes from not using exactly the same amount of force each time and the bullet settles slightly differently each time so I do it a bunch of times and take an average.
Cyphering square marks is probably part art and small part science anyways.

 

[spclark]

A trick that somebody told me was to put a cleaning rod down the muzzle with your other hand and keep it in contact with the bullet as you push/pull the seating tool which helps me get more consistent results and stops the bullet from sticking in the barrel in jam.

Yep, that's the trick I found helped me get much more consistent measurements out of a Stoney Pointe (now Hornady) tool.

Rather than risk using a threaded cleaning rod however, I bought a 36" 3/16" dia. plain brass rod at my local hardware store. If you choose this route, inspect both ends for small burrs before inserting either one into a rifle bore. This size (0.1875") is small enough to work in .22 bores but also large enough to contact the meplat on .308 bullets yet stay well clear of most of the lands.

Being brass they can happen in handling all too easy but soft enough to clean up with a fine file. Use care to keep it clean & free of grit; I wrapped some electrical tape around the end that I hold onto, wipe it off with a clean patch before & after use.

 

[spclark]

I am looking at purchasing the Sinclair model (stainless steel) that uses your bullet, and case along with a bushing and two locking collars. It uses measurements off the bullet in combination with the distance from the case head.

This one?

http://www.sinclairintl.com/.aspx/pid=35491/Product/Sinclair-Bullet-Seating-Depth-Tool

Ought to work OK I guess though I've never used one.

Anything short of the (admittedly rather tedious) procedure outlined by 4Xforfun demands a careful and practiced routine to get reliable, consistent results. The bullet jam method pretty much guarantees accurate results if you're careful with the bolt-closing operation.

I've done something similar with AR uppers & bolts stripped of firing pin and ejector, particularly when frustrated by irregular readings from the comparator method or when working out a minimum case shoulder bump increment.

 

[BoydAllen]

I have both, and initially I thought that the Hornady (Stoney Point when I bought it) was less accurate. Since then, the Forum Boss of this site has assured me that he and others are able to get good repeatability with the use of proper technique. If I have the threaded case, I prefer the Hornady, but the Sinclair is more versitile. As an aside, if you measure the "headspace" of a fired case from your rifle, a well as the threaded case and note the difference, all that remains is to add the difference to what you get when using the threaded case, and you will have a number that is correct for your chamber. There is no need to modify a fired case to get an accurate measurement for your particular rifle.

 

[rocketron]

i went with the Sinclair for the simple reason i can use the brass i shoot in the rifle. no need to have a box full of modified cases. most you will need for the Sinclair is a differant guide for the action.

with multiple measurements i useally get about .002 difference. i install a rod guide, point the muzzle to the floor and drop the bullet. this way gives me the most consistant measurements. if i try to seat the bullet any other way the difference is larger.

i like mine. only draw back is the bullet does get stuck in the barrel.

 

[bozo699]

I have both, and initially I thought that the Hornady (Stoney Point when I bought it) was less accurate. Since then, the Forum Boss of this site has assured me that he and others are able to get good repeatability with the use of proper technique. If I have the threaded case, I prefer the Hornady, but the Sinclair is more versitile. As an aside, if you measure the "headspace" of a fired case from your rifle, a well as the threaded case and note the difference, all that remains is to add the difference to what you get when using the threaded case, and you will have a number that is correct for your chamber. There is no need to modify a fired case to get an accurate measurement for your particular rifle.

I agree except it is easy for me to make my own modified cases from cases fired in the chamber I am measuring. If I use the same technique on 15 try's 10 to 12 will read exactly the same the other two or three are usually very close, since the measurement is only relevant to your needs and to no one else or no other rifle as long as you stay consistent in your measuring with the hornaday tool you will be happy with your results I believe. I was not trying to sell you Boyd just agreed with your post and added my $.02
Wayne.

 

[alf]

The only tool I need is a Bic lighter........

 

[bozo699]

Alf,
Does that effect your moly any or not?
Wayne.

 

[Keith Glasscock]

Sorry Nat, I know I'm not answering your question...

I don't use a tool either - I am one

I just seat a bullet long (in a fully fire-formed case - zero headspace) and slide her into the chamber all the way till the shoulder touches. If the bullet doesn't "grab" the rifling, I'm too short and start over. With the bullet "grabbing" I slowly seat deeper until the bullet doesn't "grab" any more. I use that as the basis for my measurements. While I have no idea where I am from the "exact" zero, I can repeatedly get my zero point figured out and seat accordingly. Unfortunately, this is a bit time consuming.

I have double checked my results with a little black on the bullet and I get a smudge-not a scrape at my zero point - I must be close...

 

[alf]

Does that effect your moly any or not?

Nope, wipes right off.

I'll do it several times to get to where I want to be, might double check with a new bullet, then use 'em for foulers. No biggie.

 

[bozo699]

Does that effect your moly any or not?

Nope, wipes right off.

I'll do it several times to get to where I want to be, might double check with a new bullet, then use 'em for foulers. No biggie.

Thanks Alf, Where in the flame is the best place? and do you just roll it one turn while in the flame?I have used a sharpie but have been using a lot of moly and the sharpie is harder for me to see and was going to try your method
Wayne.

 

[bsekf]

I use a resized case, one with a split neck will work. Cut a slit down to the shoulder. Size in a collet sizer until a bullet will stick in it. Push bullet 1/8" into case. Carefully chamber the case/bullet and slowely close the bolt. Carefully open the bolt and remove the case/bullet. Measure with a Stoney Point Comparator. Take many readings, if the bullet sticks in the rifiling your case neck is too tight and you are jamming it. This gives you a measurement to use when you adjust seating depth. I have tried the other 2 methods and this gives me the most accurate measurement.....and......it's cheap!

Bill

 

[Jay Christopherson]

I use the Sinclair gauge that you are considering and as long as you use a hard jam as your reference (i.e., jam the bullet hard into the lands), it works great. I also use a case with the neck cut to allow a bullet to seat as you close the bolt.

Both references are very close, but I have found lately that the Sinclair gauge gives less variance. The case method works great, but you have to be super careful when opening the bolt and remove the cartridge so that you don't mess up the measurement.

I usually do 3 measurements in a row with the Sinclair gauge and generally speaking, they are all within a thou of each other, if not identical. So I guess this is a vote for the Sinclair gauge.

 

[alf]

Where in the flame is the best place? and do you just roll it one turn while in the flame?

I keep the flame an inch or better away with a slow spin, once or so around.

We're just wanting to blacken it with soot, not make dinner....... ;D

 

[artbosco]

A trick that somebody told me was to put a cleaning rod down the muzzle with your other hand and keep it in contact with the bullet as you push/pull the seating tool which helps me get more consistent results and stops the bullet from sticking in the barrel in jam.

I think most of the discrepancy with these tools comes from not using exactly the same amount of force each time and the bullet settles slightly differently each time so I do it a bunch of times and take an average.

Cyphering square marks is probably part art and small part science anyways

The TRICK IS ACTUALLY IN THE INSTRUCTIONS THAT COMES WITH THE HORNADY TOOL.

It really helps determine when the bullet just touches the lands. I use a piece of wood dowel from Home Depot vice a cleaning rod. I prefer something soft as it slides on the rifling. It saves my coated rods from getting cut up too.

Another TRICK, IS TO MAKE SURE THAT THE CASE IS ALWAYS SCREWED ON TIGHT. IF IT LOOSENS, THE MEASUREMENTS ARE WRONG. CHECK IT OFTEN.