Measuring to lands???

[cowtownup]

I'm trying to measure OAL to the lands with 2 different projectiles just for the sake of knowing more and recording more information regarding my handloads. I don't have the fancy equipment required so I have resized and trimmed a case to trim length and have slit the case neck as shown in the picture. I lubed the inside of the case neck and barely seat the bullet then chamber the round and measure. Here are the results:
1. 175 grain SMK ".............2.890"

2. 165 grain SpitZer BT.......2.816"

My question is why such a longer OAL to the lands with the 175 SMK. The projectile appears as if it would catch the lands sooner and seat deeper than the 165 SpitZer... I just want to make sure I'm getting good readings. Can anyone offer some explanation.

 

[CarJunkieLS1]

Those bullets have different Ogive locations. If you look closely you can see that the "flat" non tapered section of one bullet starts sooner that the "flat" part of the other one. That is where the difference in measurement is coming from.

 

[kerreckt]

I agree. Where the bullet first touches the lands is dependent on the location of the ogive. Different profiles within the same caliber can have different ogive locations. This location is determined by the profile of the bullet. It is this location plus any setback that determines the "jump" distance to the lands.

 

[Jcinnb]

If you really are into it, and you will be sooner or later, get the Hornady gauge, That, and the bullet insert will cost you about $40.

Then you will get the comparator since you will realize that only the ogive matters,

I had the Sinclair gage and was sending some keyholing so I thought I was screwed up, so I bought the Hornady gage. Now I check with both and usually are within a .001.

You will just be sure with a gauge.

Good Luck

 

[fguffey]

Slit the neck of the case and then lubed the bullet?

I am the fan of bullet hold, I want all the bullet hold I can get, I am also the fan of transfers and standards. Problem solved, I have all the fancy tools, I do not use them. I push the bullet out of the case with all that bullet hold into the lands, then I remove the transfer (case and bullet) to the seating die. I transfer the measurements from the chamber to the seating die without fancy tools.

I have resized and trimmed a case to trim length and have slit the case neck as shown in the picture. I lubed the inside of the case neck and barely seat the bullet then chamber the round and measure.

Resized? After resizing do not forget to add the 'bump', if you full length sized the case to minimum length add the difference in length between the fired case and the full length sized case from the shoulder to the head of the case.

1. 175 grain SMK ".............2.890"
2. 165 grain SpitZer BT.......2.816"

Difference, I make one transfer, drill out the flash hole/primer pocket, seat another bullet, make a transfer then remove it and adjust the seating die to the transfer. Save the transfers, label the bullet on the case, it is not necessary to start over every day unless you decide to shred the neck to lesson bullet hold.

F. Guffey

 

[witchhunter]

Guffy does it right. Nothing can give you a better measurement than the bullet and case you will be using.

 

[jerkface11]

http://www.midwayusa.com/product/74...-24-25-26-28-30-calibers?cm_vc=ProductFinding

That's what I use. Just get one bullet seated where you want it measure it with the comparator and that's the number you want with every bullet.

 

[Blue68f100]

I've been doing it like Guffey for 35+ yrs now. Nothing like use the real thing to measure with. I do it for every bullet I shoot. I did buy a RCBS Precision Mic for a couple of calibers that I load for multiple rifles. This allows me to use a shims to compensate for the different shoulders.

 

[cowtownup]

I can't quite understand what Guffey is saying with the "transfer".. Can you explain it to me once again please.. Thanks..

 

[anothernewb]

I'm a little curious as to the exact process too.

 

[Fatelvis]

I've used the slitted neck method, it works well. You can also use neck bushings on the trial piece of brass, to give about .0005" or less neck tension. Sometimes the bushings you have on hand work just right for enough bullet pull to barely hold, until pushed in.

 

[Blue68f100]

Once you have the chamber set your OAL with what ever bullet you are using. You need to transfer that setting to the die. You can measure it and try to match it or just put in the press with the seating stem backed out. Then you run the stem down till you feel contact and lock it down. Now load a dummy up and confirm in your gun using a marker on the bullet. Good possibility that you will make contact. This is your max OAL with the bullet contacting the lands. You need need to back it up what preset you want. Find out what thread pitch you seating stem is and 1/tpi = xxx. With this you have an idea of how far to turn to for a particular distance. This is where I like the RCBS Precison Mic. I can actually measure this distance and have a reference number I can use. This allows me to confirm I'm so xxx off the lands.

I try to use a piece of junk brass for this. I size it (shoulder set back 0.002") then cut the slots, de-burr your cuts. All brass reacts differently. Most of the cases 3-4 slots are just about perfect. You want the bullet to be held but not so hard it is jammed into the leads.

 

[RainDodger]

Many years ago I inherited all my grandfather's reloading equipment. In that stuff, there was a weird .30-'06 case in which he had drilled out and tapped the primer pocket. A long brass screw was inserted in the case.

It took me a number of years of reloading before I remembered that little gizmo and immediately knew what it was. A home made tool for measuring base-to-ogive lengths. A non-professional tool that works great. A pretty easy weekend project to put together I'd say. Place your bullet of choice in the case, chamber it and then turn in the brass screw until you feel the bullet touch the lands. Voila!

 

[gamestalker]

I do it just like fguffey, and I agree you don't need expensive tools to determine a precision olgive to lands location.

GS

 

[cowtownup]

Well since I was measuring over and over 2.890 to the lands, I backed off .025 and went with 2.865 OAL for my loads. I load them one at a time so I'm not concerned about the magazine. Is this a good starting point?

 

[Reloadron]

Well since I was measuring over and over 2.890 to the lands, I backed off .025 and went with 2.865 OAL for my loads. I load them one at a time so I'm not concerned about the magazine. Is this a good starting point?

That would be as good a starting point as any.

When creating a standard case like this, to be used as a transfer standard, there are a few caveats worth noting. Here is an example of what I am getting at:

Below we have some Sierra 30 Cal 168 gr Match King bullets.


The nice people at Sierra tell me these bullets are guaranteed weight of 168 grains +/- 0.1 grain. With that weight change goes a slight change in bullet length. Take a look at the next few images as we measure the length of a sample of these bullets:

This bullet has a length of 1.209"


Let's take a look at another bullet:


The second bullet has a length of 1.213"

Depending on our seating die we can end up with two different COL dimensions when these bullets are loaded. While we are not measuring base to ogive of the bullets we do know they vary. This is worth a read on the subject: Effects of Cartridge Over All Length (COAL) and Cartridge Base To Ogive (CBTO).

<EDIT> Also for those curious as to drilling out the primer pocket give this older thread a read as it covers it well. </EDIT>

Ron

 

[hartcreek]

cowtownup...The way that you are measuring the chamber is the way that is given in my 1950s reloading manuals and it still works.

I have seen different ogives in the same brand bullet same size just different lots.

 

[kingmt]

I make a stranded somewhat like others have explained. I don't cut the neck since I want my standard to be rigged. I seat my bullet long then finish seating it with the bolt of the rifle. I then seat it a ths at a time painting it with a sharpy till I see there is no contact then another .002". I do this with my rifle that has the shortest chamber in that caliber. This makes a rigged stranded that I can crank my die down with a good bit of hand force without worry of changing my standard & insuring a good transfer. I have found lightly touching allows for torance in the setting.

A easy way to get the .002" would be sticking a filler under the head.