Determining Where the lands Start to Establish a C.O.A.L. ??

[5.56Geo]

I am developing a hunting round for my .270Win with Barnes TSX bullets. Barnes recommends that the bullet sit about 0.05" away from the lands. I do not have a Stoney Point Gauge and am running out of time and weekends. What are your thoughts on the method where you cut the neck of a case and fit a bullet as far out as possible and chambering it so the lands seat the bullet then subtracting the .050". ...doing the subtracting after an average of several chambering's?

Have any of you ever used this method, if so how did it work for you?

...or is there some one in or around San Diego (Oceanside) that would be willing to help me that has a Stoney Point Gauge? Your comments are welcomed.

Thanks guys. -George

[jstone]

You can do it the way you mentioned, just do it multiple times to see if your measurements are repeatable. Another thing you can do is just load it to the OAL listed in the barnes manual, or magazine length.

If you have a good sporting goods store close you could find some of the barnes ammo and measure it, but they probably just load it to the OAL listed in there book. I have had the best luck with barnes bullets when loaded to barnes suggested OAL.

I mostly load the 22 cal barnes but I have loaded some for 30-06, and there suggested OAL always works for me.

Edit: I have used the method you mentioned before I bought the hornady tool. You should be able to just use the book OAL and be good to go. It sounds like you have the book but if you dont let me know what bullet your using and I could give you the info, or I could scan the page and email it to you.

[Warg]

Yes, you can use that method two different ways (actually more, but these are the easiest):

1. Measure the length to bullet ogive when the bullet is touching the lands
2. Measure the OAL at the lands

Be very careful when loading the round to avoid hitting anything and repeat your measurements at least five times.

For method #1, you'll need a bullet comparator for 270 and an adapter for your caliper. It can be difficult to measure at the ogive with the split case method as you can seat the bullet further when trying to measure.

For method #2, use a permanent marker on the ogive (or thereabouts) to ensure you actually in the lands enough to make a mark and making sure you're not hitting something else. Touch up after each measurement.

I prefer measuring at the bullet ogive for bolt action as I've found more variation in bullet lengths with the bullets I use compared to ogive measurements. Thus, I have slightly more variance in COAL, but less at the lands. Not sure about the variation among TSXs.

With the OAL tools like that from Sinclair or Hornady this process is a heck of a lot easier, but I know lots or folks who have used the split case method for many years with great success.