match 762x51 help/advice

[hawk_550]

so i am moving my reloading from 308 brass to 762 brass, my 308 home roll was kinda bland but offered good results the load was as followed

308 win casing ( winchester brand brass)
2.005 brass length
175 smk
2.185 seating depth from ogive
41.0 imr 4064

my last gun had a 1:10 twist and this did really well for me, it was my first match load, i now am shooting an ar10 type rifle with 1:11 twist 18" polly rifled barrel.

i want to stick to 175 smk's and 178 a-max bullets and imr powder and cci primers but i want to switch to 726 lc brass, its just more common and easy to get, but i am not sure where to start as far as loading goes.

should i start at 38 grain and go every .5 up to 41 grain or until i see over pressure signs on the brass and once i find something close then work up in .1 grains ?

getting me set up on the right path would be most helpful

 

[jonbearman]

I think you are on the right track with starting at 38.0 and working up.I dont know if the weight is the right weight in a gas gun.I am sure that someone will chime in.

 

[gaboon]

I would trim the brass to 2.015 and I believe mag coal is 2.810. I run 2.62 off the ogive in my bolt gun. The 7.62 chamber is supposedly longer than a 308win.

 

[hawk_550]

i am using magpul pmags and my magazine seems to be 2.95 on the inside that would be max oal tip to bottom of brass. if i try to load to touch the lands how would i know if i am touching ? marks on the bullet ?

this rifle does shoot my old load pretty dang well i though maybe i could try and duplicat it only using LC brass, only issues is having to start over with the powder and working up.

another thing that confuses me is ladder testing, i just want to make sure i am working the load up properly

 

[gaboon]

If load to mag. Length you will not touch lands. If you load single shot you can lengthen the coal. You find the lands by taking a dummy load and load it long. Then place in the in chamber and close the bolt. Open bolt carefully and you should see some marks. That would be touching the lands. Do it a couple times and measure each time. That will tell length.