Do you load target 308 to suggested OAL or X short of lands?
- Thread starter Kryogen
- Start date
I measure OAL at the ogive, for a certain jump/jam for each load. Hornady OAL gauge and comparators. I shoot hybrid bullets exclusively, they are relatively insensitive to seating depth, so the OAL is mostly for consistency round to round. Also, if you are going to measure off the ogive, you pretty much have to use a seating die that seats off the ogive too, because variations in lengths will affect seating depth if you use a die that seats from the tip.
As for "ideal length", that is trial and error. Read up on seating depth for VLD bullets, they are very weird when it comes to jump/jam. Just gotta shoot em and see what they like.
And lastly, this whole subject is of limited usefulness in a factory rifle with their ridiculously long throats.
As for "ideal length", that is trial and error. Read up on seating depth for VLD bullets, they are very weird when it comes to jump/jam. Just gotta shoot em and see what they like.
And lastly, this whole subject is of limited usefulness in a factory rifle with their ridiculously long throats.
ultimate_monkey
CGN Ultra frequent flyer
- Location
- victoria BC
when i do my load development, i start with every thing .015" off the lands, (i mainly use smk bullets and this has always been a great base line) then once iv decided on my poweder charge i play around with jump/jam to find the best performance
I do target load powder charge work ups with the bullet seated out to a light jam(around .015"), if that particular rifle's throat will permit.
Once the center point of the best node is established, then seat progressively deeper in .005" increments to best grouping.
Once the center point of the best node is established, then seat progressively deeper in .005" increments to best grouping.
Always off the lands... It is the only reliable benchmark for a given rifle. I use LONG for caliber bullets dabbed with gungrease with a slide fit in the case inserted into chamber and action closed and then remove... Your maximum COAL will be readily apparent... As others have said, I then work up my loads 0.015" offthe lands and then play with OAL to tweak best accuracy.
Started out early days with a rcbs casemaster for the 6.5x55(my personal go to accuracy cart., tho, I do load for many other cals. with the following proceedure). And a versatile and usefull tool that casemaster is. But not cheap.
Over time, I've simplified(being a notoriously low budget type guy), to use what is at hand. We often work up loads for a new to the scene, or a good friends latest gun, from out of the backpacks while camped out in the bush. Plenty of 1/2 moa results have come of these camp developed loads too. Maybe half a dozen .308's so far are all tuned up and bugholing. (varget and 155gr Amax, being a sure fire winning combo)
These days, the procedure is to seat yourself a dummy cart., made from collet neck sized fireformed brass, with the bullet seated way out to long jam, far enough out to where the bolt handle will not fully close with normal pressure(& Don't be forcing it closed!). The bullets ogive is smoked black with a bic lighter and carefully chambered. On extracting, the full width of the lands can be seen and measured, as can the depth of the ogive's penetration into the leade. Bump the seater stem back a wee bit and try again, and again, re-smoking each try, till the caliper shows a shiney spot to the depth of your chosen jam. (Note: Even with near perfect loaded round concentricity, not all of the lands shiney spots are likely to be even or identical, go for your measure with the one or two that are showing the most jam)
A Forster or Redding BR seater with Micrometer stem really pays off in ease and repeatability .... And dead straight, low/no runout, match grade cart's. are the result as well. And, makes it easy to advance seating depth 2 thou. or so per 100 rounds to compensate for throat erosion.
Thats all I buy these days(they work sooo well!) along with a Lee collet sizer and Redding body die ... for every cal. that is expected to shoot it's best.
Good shooting Kryogen.
Edit: Why I like to develope optimum powder charges with the bullet jammed, is all about pressure. It decreases as the bullet is moved deeper into the neck to a jump. Rarely have I needed to re-tweak a powder charge after finding
optimum seating depth.
Over time, I've simplified(being a notoriously low budget type guy), to use what is at hand. We often work up loads for a new to the scene, or a good friends latest gun, from out of the backpacks while camped out in the bush. Plenty of 1/2 moa results have come of these camp developed loads too. Maybe half a dozen .308's so far are all tuned up and bugholing. (varget and 155gr Amax, being a sure fire winning combo)
These days, the procedure is to seat yourself a dummy cart., made from collet neck sized fireformed brass, with the bullet seated way out to long jam, far enough out to where the bolt handle will not fully close with normal pressure(& Don't be forcing it closed!). The bullets ogive is smoked black with a bic lighter and carefully chambered. On extracting, the full width of the lands can be seen and measured, as can the depth of the ogive's penetration into the leade. Bump the seater stem back a wee bit and try again, and again, re-smoking each try, till the caliper shows a shiney spot to the depth of your chosen jam. (Note: Even with near perfect loaded round concentricity, not all of the lands shiney spots are likely to be even or identical, go for your measure with the one or two that are showing the most jam)
A Forster or Redding BR seater with Micrometer stem really pays off in ease and repeatability .... And dead straight, low/no runout, match grade cart's. are the result as well. And, makes it easy to advance seating depth 2 thou. or so per 100 rounds to compensate for throat erosion.
Thats all I buy these days(they work sooo well!) along with a Lee collet sizer and Redding body die ... for every cal. that is expected to shoot it's best.
Good shooting Kryogen.
Edit: Why I like to develope optimum powder charges with the bullet jammed, is all about pressure. It decreases as the bullet is moved deeper into the neck to a jump. Rarely have I needed to re-tweak a powder charge after finding
optimum seating depth.
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