How do I find the lands?

[captacademy]

Lots of good info.

 

[brubo]

I have a related ? I just measured 180 grn. ttsx using the r-p tool described earlier, I got 2.955 measured to tip. I measured the 168grn. with same method & got 2.975 Shouldnt the 180 measure longer? Am I missing something? I also did the 130 ttsx & its measuring 2.950.
I have done these measurments 3-4 times for each.
Is this a Barnes trait? Oh by the way this is in a savage 300wsm. Thanks Brubo

 

[woods]

The heavier bullet will get the extra weight by becoming less pointed. I noticed that in the 270 caliber 130 gr and 140 gr TSX's. The distance from the tip to the point on the ogive where it reaches full bore diameter is shorter on the 140 gr bullets than on the 130 gr bullets. So I could seat the 140 gr TSX bullets closer to the lands than the 130 gr bullets and still fit the magazine.

 

[ken snyder]

brubo, you arent missing with your observation. measuring bullet cartridge length from the meplat is for magazine length. The actual jump to the lands is measured from the place on the bullet that the major diameter of the bullet starts at. Different bullets have different shapes and tapers so measurements from the tip are just magazine length. Bullets right out of the same box will also have up to .015" variation in ogive length measured from major diameter to meplat. As rscott pointed out it is about" finding the correct seating depth that your rifle & load combination will shoot". I think there may be dozens of lengths that any particular load and rifle will like each other. Most of the time a handloader will not have any control over the actual jump because most seaters seat the bullet from the meplat with no consideration for the actual jump variations and are forced to find a happy average. Some shooters will final seat the bullets using a hand type seater that uses a seating cup that is long enough and has an inside diameter large enough that the bullet is seated from just in front of the major diameter which eliminates all jump variations as much as what is humanly possible. It is about jump or lack of jump, a good number or an average number. I feel that it is all about actual and consistant jump but at the same time admit that most handloaders are able to get averaged jumps to work very well. However I am way too lazy to work at finding an average so I always use consistant jump measuring and seating. A push feed tactic that works extremely well first time and every time. leaving only consistant velocity to play with.

 

[jeffwhip]

If you are going to use the Hornady OAL gauge, it is best if you take one of your fire formed cases and drill and tap it to fit the gauge.

Woods,
I went down to a local hardware store and they couldn't figure out what the threads were for the Hornady OAL gauge. Do you happen to know? If so, this would allow me to drill and tap any cartridge I own! Thanks in advance.

 

[brubo]

Thanks guys I am going to get a precision mic & bullet comparator.
Want to be as precise as possible.

 

[Tumbleweed]

I have always used a sharpie and covered the ogive area of the bullet on a loaded, dummy round. I start out seated deep and work my way out until I start to get rifling marks in the black felt pen ink. From there I fine tune my seating die to where I can just ever so faintly see the marks in the ink, I figure this is touching and not jammed. This can try one's patience though!

 

[woods]

Woods,
I went down to a local hardware store and they couldn't figure out what the threads were for the Hornady OAL gauge. Do you happen to know? If so, this would allow me to drill and tap any cartridge I own! Thanks in advance.

5/16 x 36 tap and the letter K drill bit

Hard to find and has to be ordered most of the time