When developing a new load, how far off the rifling do you set the bullet as a starter with a view to fine tuning it later?

I have a read in a couple of manuals it is better to seat the bullet "just off the lands" as a starting point, but I wondered what a ball park figure for that might be.....

Regards,

Peter

Peter,
Most suggest .010 inches off the rifling. This can be done with stoney point gages, or you can do a in-expensive way. Bolt out, drop the selected bullet gently down into the chamber. Place a small pencil or dowel rod behind the bullet gently, and insert a cleaning rod down the muzzle end of the rifle. Mark a line on the cleaning rod EVEN with the muzzle when the end of the rod makes contact with the bullet. remove the bullet from the chamber, reinsert the bolt, or close the action. Extend the cleaning rod into the chamber, until it makes contact with the breech face. Mark another line on the cleaning rod EVEN with the muzzle. Measure between the two scribed lines on the cleaning rod. That is the MAX overall length of THAT bullet and case combined. Seat the bullet .010" shorter than that measurement, and see how your accuracy is. Vary that very slightly(deeper)to see if accuracy improves or deteriorates.
If you change bullet brands and shapes you must do it again. Following the same procedure with each different bullet you try.

SP

I start with .005" into lands or longest functioning length and increase depth by .010" in three-shot groups. That will usually reveal the ballpark length.

I then repeat the best one and bracket it on either side by .005" all with five-shot groups.

With some rifles there seems to be more than one sweet spot; if the rifle in question is clip-fed that is especially nice.

For varmint and BR increase anal retentiveness appropriately.

[ 03-22-2003, 06:59: Message edited by: steve y ]

Pete E: When developing loads, I start by seating the bullet to the recommended seating depth. After I find the accurate powder charge, I load more cartridges and vary the seating depth, usually starting 0.020" off the lands and decreasing depth by 0.005" and shoot each group of loads for accuracy while watching for excessive pressure signs. Since I seldom find the accurate load with the max powder charge, I have yet to see excessive pressure signs. I seat all of my bullets using the Stoney Point bullet comparator to measure to the ogive. I never measure for the OAL of the cartridge. Hope this helps a bit. Bear in Fairbanks

Find out where your bullet will be when it touches the rifling (max OAL). Talk to manufacturers of particular bullet for what their recomended closest position to rifling for your cartridge/bullet.

Ladder Method of load development. Settle on a powder charge that is safe. Start seating bullets (15-20) at the max OAL minus the distance the manufacturer told you to keep between the bullet and the rifling, seat each successive bullet .005"-.010" further into the case and mark each case so you can keep record. Set up target @ long range (preferably 300yrds or more). Fire two fouling rounds w/ammo other than the 15-20 mentioned above. Do your best shooting (replicate conditions that you will be using load, heavier clothing in shoulder area for colder temps, etc.) and start w/longest OAL's recording the hit on the target on a target next to you (pay attention to any increased pressure signs as diff OAL's may result in different pressures). What you will find @ the end of the session is one or a couple of 3-4 round groups where a particular sequence (lets say #'s 3-5 and #'s 11-14) grouped much better than the rest. choose the average OAL of these sequences. This average is VERY close to your optimum OAL which is reflective of harmonic balance (barrel whip, and other factors) in your particular rifle. I have found this method to produce MOA or better every time. You can go hunting from there or load up 8-10 more with .003"-.005" OAL differences around the average to further refine.

Deke.