Ladder Test Seating ???

[RLP]

I am new to ladder testing and would like to know if there is a preferred seating depth. I am going to test a 6.5x47L,,308,, and 6BR. Should the testing have the rounds seated with jump, touching , or jam. I was going to try touching first but really am guessing at this point. Thanks for helping,, Bob

 

[jsthntn247]

Seat them at a .010 jam. If your loads aren't compressed, you can back off the lands ( when doing seating depth test) and don't have to worry about running into pressure.

 

[searcher]

Adding to the above post - I think .010" jam is GREAT place to start. Run through a ladder test working up to higher loads from lower powered ones. If your gun doesn't like it - go out another .005" and repeat the ladder. I have found that "my" guns almost unversally shoot best from jammed .010" TO .010" off the lands. I experimented to the point of wasting away barrels only to find that while some barrels do shoot really good (with certain bullets) WAY off the lands - I personally found it to be very remote in the course of countless variations in a few dozen barrels. That said - your rifle may be one of those "remote" situations - but I'd focus heavily on the above parameters first - then move on if these don't work. You can go to Berger Bullets' website and they offer up their method of depth testing. I'd still stick to that .020" spread first if it were me..... Good luck!

 

[lal357]

interesting I always start the other way .01 off the when I find a good node I start moving in and out but then I start at min. and load up to max for a ladder in .3 increments

 

[jimbires]

I'm a hunter , so I load to magazine length or .010 off the rifling , whichever is shorter . this way I'm sure the ammo will feed and also I shouldn't get a bullet stuck in the rifling . by starting at my max length I can only go one way , shorter , to fine tune seating depth . on powder increments I use a rounded off 1% to start with . an example ; if I'm working in the 40 or 50 grain range I use 0.5 increments . if I'm working in the 80 or 90 grain range I use 1.0 grain increments . on the next ladder I use smaller increments . I'll use 0.2 grain increments on the 40 - 50 grain cartridge , and 0.5 grain increment on the bigger cartridges .

I'm looking forward to reading this thread when I get back , I'll be gone for the week . Jim

 

[lawrence97]

Establish a repeatable baseline by soft seating or using some tool or gadget to measure a jam or the point where the lands mark your bullet. Then , after an established baseline which is a jam, work your way back to 20-30 thousandths jump. As for touching, I believe its like standing on a tightrope. If there are any bullet, ogive or case discrepancies you may find that with some rounds you may be touching more than with others and cause unwanted spikes. Start with a jam and establish max pressure and best charge with the powder and bullet combo you choose and then test for seating depth in increments of.003.

I personally size my case with .001 neck tension, remove firing pin from bolt and then seat the bullet with closure of bolt. I do this 3-5 times to verify I get repeated results. That is then considered my baseline (slight jam) and I work my way back to a jump until I find what I like. That established baseline also lets me see how much throat erosion I am getting after a certain amount of rounds and I can adjust my seating depth accordingly.

 

[Raythemanroe]

Starting with your round into the lands would be the safer route, the alternative would be work your way to the lands and most people would say that shouldn't be a option.

 

[RLP]

Thanks for the response. I will start the testing with .010 jam . Makes sense to start and find the max pressure load in the first sitting . Thanks again,,Bob

 

[treeman]

If it's for target shooting I start in the lands to find max.in my rifle. If it's for hunting I start at magazine length or .020 off which ever is shorter. That keeps you from running too hot when changing seating depth. After you find seating depth Your rifle likes You can adjust powder charge for lowest es and sd.