Throat measurment problem

[geocole]

I am new to reloading for a rifle, and have a problem.
I took a 30-06 case, full length resized and used a fine hack saw to cut one side of the neck, so I could measure free bore or bullet to lands.
I checked the length of the bullets and they ran 1.105 to 1.112. They are Speer FMJ-BT 150gr
I inserted the bullet into the case (which fit snug) put it in the rifle and slowly pushed the bolt close. I then ejected the cartage and measured with digital calipers. I got 14 different readings, 4 were the same readings. Readings are
3.234 to 3.241, one of the 1.110 bullets read 3.234 and one bullet 1.106 read 3.238.
I rechecked about 5 twice and would get the same reading as the first time. I zeroed my calipers 5 times
Why is there such a large variance in the readings is my problem.
The rifle is a Savage 110. I have only shot it 50 times so far. 20 factory ammo and 30 reloads.

Thank You

 

[taliv]

measure from the ogive, not the meplat

 

[Walkalong]

so I could measure free bore or bullet to lands

Load the bullet backwards and use the bolt to seat the bullet the last little bit. It will show you how much freebore you have. This is not very important though. You need to find out what overall length shoots well for that bullet in that rifle. I would start by using an O.A.L. that has the bullet just touching the lands if it will fit in the clip/magazine. The O.A.L. will vary some because of the differences in bullet length. Get a tool such as the Stoney Point bullet comparator for getting the measurement you need. The ogive is where it is at.

Check the link. A good explanation there as well as the tool.

 

[Bad Flynch]

Having been the victim of many throat measuring schemes, allow me to supply you with some conclusions.

1) Bullets are not the same length from tip to ogive and the ogives can vary quite a bit, even in a single batch. Those things give varying readings.

2)When you close the bolt and jam the bullet into the ogive, it sticks a little. When one extracts the thing, the bullet can pull out a little, giving poor readings.

3)The case can give trouble, too, unless it fits the chamber rather tightly. If it is loose in the chamber, sometimes the reading will be different.

What you really want to know is just how far it is from the case head to a certain diameter on the bullet. Lets say you are using a 22 caliber rifle of some sort. You might want to know how far it is from the case head to the .223 diameter on the bullet. Turning the bullet around, as previously suggested, may help all of this a little. Once you know how far it will be to a certain diameter, then you will know just where to place that diameter in relationship to your case heads, even for new bullets.

 

[USSR]

Spend the $$$ and get the Stoney Point OAL Gauge and a bullet comparator, as they will give you case base to bullet ogive readings, with is what you want.

Don

 

[Walkalong]

The Davidson tool is inexpensive and works very well also.

This simple one by Sinclair works fine as well. I have one of these.

For my bench gun I have a custom one made from a short piece of barrel with a partial chamber cut into it with the reamer that cut the chamber on my original barrel. I still use it for other barrels.

Bad Flynch is right about bullet variations. Don't expect things to be perfect all the time. A bit of variation won't hurt. Strive for perfection and settle for reality.

 

[geocole]

Thanks everyone for the replies.

I do not shoot real good since I am one day older than dirt, but I do enjoy reloading, and want to do the best that I can.

Walkalong I think I will get the sinclair # 09600 as it has the .224 cal which I would like to get next.

 

[Walkalong]

Sinclair has a lot of cool stuff. Good luck reloading the 30-06. I think you will have a lot of fun working up a load that shoots real well in your rifle. It's very satisfying.

 

[MinnMooney]

Wow! Lots of great information from both THR folks and the links that they've set forth.
Thanks.... I've learned a lot by reading this thread.