Depth seating gages...Need help

[CoverDog]

I have both the Sinclair depth seating gage and the Hornady gage with their modified case. When comparing the two there not close. These are the numbers:

This is for a 204 Ruger case.

Sinclair gage reads 1.647 using a fired case from my gun.
Sierra 39gr Blitz King is .7425
Total OAL to the lands is 2.3895

With the Hornady gage and modified case it is 2.457 a difference of .0675 Thats a big difference, Why?

Using a Sinclair bump gage, my once fired brass measures 1.0533 and the Hornady modifies case measures 1.0532 a difference of .0001 Both cases are trimmed to 1.840

Which gage would you go with? I believe the Sinclair results are the one I should use. Bullets seated to 2.390 show marks where they have contacted the lands.

Any thoughts would be greatly appreciated.

P.S.

just ran the number using a Berger 35gr here are the results. OAL using the Sinclair gage 2.247 OAL using the Hornady mod. case 2.408
A difference of .161 even larger then with the 39gr Sierra.

 

[fdshuster]

CoverDog: Different gauges, made by different manufacturers have different dimensions. The actual point of contact on the bullet ogive is an arbitrary number depending who made the measuring tool: only takes a few thousandths difference on the diameter of the hole. Even gauges made by Sinclair, for example) could have small differences. Fagetaboutit--- pick one gauge, take the depth readings obtained with that gauge and use it exclusevely. Same variences will happen if using different tools to measure headspace.

 

[CoverDog]

If I was using a 'bullet comparator' made by two different companys, then I could see where there might be a difference in the diameter of the the hole, and where it contacts the ogive.

The tools I am using take the measurement off a bullet that is placed in the barrel touching the lands. I use the same bullet for both tool measurements. Both cases, the one fired in my gun and the modified one from Hornady are trimmed to the same lenght and are within .0001 of each other in a shoulder bump gage.

This is why I am confused as to why the large difference of .0675 in OAL with the Sierra 39gr and almost double that ,.161) when using the 35gr Berger.

 

[DonM]

YOu can probably ask 10 shooters this question & get several
different answers. Here's what works for me & has for years.
I use the Stoney Point OAL Gauge,the straight one) & a
modified case for the rifle,chamber) that I am working with.
I take one of the bullets that I want to use & put it in the case & install the gauge/with the modified case holding the bullet into the chamber & gently push the rod forward until it
just touches the lands. Then lock the set screw on the Stoney Point OAL Gauge. Then I use a Sinclair 'Nut' to check the OAL at the Ogive of the bullet using the depth setting I have achieved on the Stoney Point OAL Gauge. Then you can set the seating depth according to your intended OAL, like -.010 from the lands, or whatever you wish to test. You are not comparing apples to apples by using two different type gauges. Pick the one you like & forget about the other one.You are on the right
track, but confusing yourself with all the gauges. Also, the
measurements are going to be entirely different with different weight bullets, & in most cases even with different brand of bullets of the same weight. YOu need to do the measurement similar to what I have described for 'every weight & brand bullet' when you use a different bullet. Oh, by the way, I looked until I found the tap to make my own modified cases &
I only use cases fired in that rifle,chamber). There is only
one measurement that you need to concern yourself about, & that
is the measurement with the bullet just touching the lands. I
normally do this measurement two or three times until I assure
myself I have a correct measurement. After you have achieved the
measurement at the lands, then you can adjust your bullet seater to the desired measurement, and again I check that
measurement with the Sinclair nut & the bullet seated in a
case I will be firing in the rifle to achieve an OAL again
like -.010 from the lands, or in some cases +.010 into the lands
as in VLD type bullets. This is probably about as clear as
muddy water, but, hope it helps your confusion.

 

[CoverDog]

DonM....Yes the Stoney Point is the Hornady gage. And your method is what I have been doing. But if I use the Hornady gage measurements and make up a cartridge and then use the measurements from the Sinclair and make up a cartridge I have 2 rounds that are .0675 difference in OAL.

I know the OAL will be different with another brand of bullet but when testing with the Berger and doing the same measurement with each gage the OAL with the Berger is .161 different between the two methods.

If the Hornady info is correct, then the Sinclair info would have me 'jumping' alot to the lands. If the Sinclair info is correct the Hornady info has me 'jammed' way to much into the lands.

Both methods are somewhat different, but the end result should be the same,or close) and it's not.

I would think they should be much closer in OAL then what I have seen.

 

[gambleone]

CoverDog,
I tried the sinclair gauge & did not like it. Could not get accurate measurements. Bought the Stoney Point,,Hornady) & love it. For me, it is much easier to use & very accurate. I use a comparator to measure the length & use that length to seat bullet. Like fdshuster said, it is an arbitrary number that you use as a point of reference. Try this: Use the Hornady tool to measure to the lands & do this until you get the same distance about three times. That should be it. Make sure you push the tool all the way in so the case seats. When you pull it out, make sure the allen screw is tight on the end or it will slip & give you a false measurement. The tighter your seat is the harder you have to pull which can make the back end slip. Hope this helps.

 

[DonM]

Well, I guess my information was a clear as muddy water. So, let me try again. Use the Stoney Point OAL Gauge along with a
modified case for that particular rifle chamber & insert the bullet you wish to use into the modified case. Now, insert the
Stoney Point Gauge with the modified case & the bullet into the
rifle chamber,after having removed the bolt of course). Gently
slide the rod on the Stoney point OAL Gauge forward pushing the bullet toward the lands very slowly. When the bullet first touches the lands lock the set screw on the Stoney Point OAL Gauge in place, & remove everything from the chamber. DO NOT
take a measurement from the Stoney Point OAL Gauge. By doing so
you are going to be required to measure to the tip of the bullet
& as we all know most bullets are somewhat irrelugar & you are going to get varying measurements. This is when I use the Sinclair Nut & insert the proper caliber marked on the Nut down on the Ogive of the bullet,still in the Stoney Point OAL Gauge). This will establish the measurement of the bullet at the Ogive touching the lands. This is 'THE ONLY' measurement
that you need. Write that measurement down. Then you can make
the necessary adjustments to your bullet seater to acheive the
desired OAL when seating the bullet. After seating the first bullet in a case that I will be firing in the rifle I check the OAL with the Sinclair Nut. Once the desired OAL length is achieved I then write that down in my log for that rifle so I will have that OAL recorded for future reference. If you follow
the process I have described to you it is 'IMPOSSIBLE' to come up with a difference in measurement. Now, if this is still as
clear as muddy water please call me at 606-34809327 & I will be
glad to go over your situation with you on the phone.

 

[Innovative]

CoverDog .........

Check out this article,with pictures). It shows how I check bullet seating depth. http://www.larrywillis.com/OAL.html This new tool provides the most consistent measurements, and it also measures the exact clearance,at the shoulder) that YOUR handloads will have in YOUR chamber.

- Innovative

 

[CoverDog]

DonM....your instructions were crystal clear, and I have done it like that for years. My only concern is if two companys put out a product to do the same thing, measure OAL reguardless of the process, the end result should be the same,or at least close).

I don't feel that a .0675 OAL difference using a Sierra 39gr bullet or a .161,even larger)OAL difference when using a 35gr Berger is anywhere near close to each other.

So the $20,000 question...which companys product results do you trust, and then use?

My thanks to all that have replied.

Cover Dog

 

[DonM]

CoverDog

The process that I am using is basically the same as the
Larry Willis article, but with the 'nut' instead of the
Micromoter. That is a really nice looking tool. I think that
if you just choose one of your methods & stick with it that
you will be fine. It is just a different tools for achieving
the same end. The difference in the measurements should be
becasue of the two different tools give a different measure-
ment becasue of the way they are made. One thing for sure is
that you do not want to use the OAL by measuring to the tip
of the bullet, which I am sure you are aware of. Now, I
am/was assuming that you were interested in getting the bullet
close to the lands. If you are loading a 'hunting round' to be
fed through a clip that is a totally different situation. If
you are interested in locating the lands & having your bullet
+ or - so many .000 from or into the lands the process that I
have been using for several years has always worked well for
me. One other difference is that I do not use the split case.
I play with different size neck bushings until I get a snug
but not tight neck tension. The bullet in the modified case
must be free enough to slide easily, but, still not be a
sloppy fit. The difference in the 39 grain & the 35 grain bullets has to be in the ogives of the bullets. Two totally
different bullets. I have a switch barrel 40X in .222 Mag Imp.
that I use on Prairie Dogs. I am sure there are others, but,
so far the only bullet that I have found in 40 grains that works well for me is the Sierra 40 Blitz King. It has a flat base & will reach the lands. The other bullets that I tested
all had a boat tail & there was not enough bullet in the case
for me to feel comfortable with while transporting to the PD
Fields. The barrels that I have for this rifle are very
apparently set up to shoot a 50 grain bullet. Anyhow, enough
rambling, good luck with your problem.

 

[fdshuster]

CoverDog: All previous directions/instructions are the 'standard' that we all use, and get excellent results with. It's really not complicated, as long as you use one tool only! Sinclair and Hornady, like Chevy and Ford, are under no obligation to make their products conform. They both arrive at an accurate, repeatable dimension, and since that dimension is a reference only,both are valid. I began with the Sinclair nut & it worked fine until trying to get repeatable measurements on the 'long and skinny' 204 Ruger case. Trying to keep the 3 points of contact from 'wiggeling' around was a problem & I kept getting different numbers, although only by .003' to maybe .006': just enough that I could not rely on them. It was then I discovered the Stoney Point/Hornady that attaches to the blade of the dial caliper, eliminating most, if not all of the 'wiggle'. Now, I prefer that tool, and have put the 'nut' aside and use only the S.P/Hornady. One thing I did learn about the Hornady tool, from this sites moderator: watch the off-set cut on the clamp attachment: if you get it 'up-side down', your measurements will be crooked, when looking at the gauge/calipers from the side. Since I was 'shown-the-light' it is my first choice. 48 yrs. at this 'game' & still learning.

 

[DonM]

Frank, sure enjoyed your post. You hit the nail right on the
head. Come to think of it I have had some of those Hornady
measuring devices that attaches to the blade of a Dial Calipher
& have never used them. I think I need to drag them out &
play with them. I have been loading for many, many years, and
like you, I learn more all the time, & probably still have a lot
to learn yet. That is what makes reloading so enjoyable for me.

 

[bsekf]

Guess I am old fashioned, I use a fired case with a slip fit neck. Hand seat the bullet long and close the bolt on it. It takes some trial and error to get an accurate 'jam' measurement. I use the Hornady tool that fits on my caliper to measure the OAL. In my notes I record the bullet, measurement and the part number of the tool. ,You can measure a 7mm with a 6.5 and etc., so be sure an record which you used.) When I start testing I start .005 long and work back by .005's. Your 'jam' OAL is really just a base point. I made a tool like the Stoney Point but found it harder to get an accurate measurement than the above method.

Bill

 

[jerrold]

I ran across an old saying once that is a perfect fit to this discussion- 'A man with one clock knows what time it is, a man with two clocks is never sure'