Seating depth affect???

[sturner]

I just worked up a load for a LRT 308 in a manners stock with 168 AMax my ogive is .02 off the lands but when I shorten them up my group went to crap.I had to take the front plate out of mag box and trimmed a little off the feed ramp
But the 308 is so easy to work up a load for if I didn't have 1200 of these 168s I would have just shortened up and started over with another bullet

 

[okie man]

Are you stuck on the all copper bullets and 150 grain weight? The mild velocities of the 308 allows you to use just about any sensible weight bullet of cup and core construction made for the intended purpose. Also know varget isn't the only powder for that cartridge. I get more velocity and lower es and sd with imr 4064 and accuracy is just as good or better. It's usually $5 a pound cheaper and easier to find . My theory is feed the gun what it likes, not what I like!

 

[CaptnC]

J. E. Nailed it!

Sure you might end up changing to a different bullet,but I have found in my short time reloading for AR platform rifles...you London to mag length and start working up your load.

I've told the guys on the Grendel forum a few times...."don't sweat with all the seating depth work! You really can't load past mag length, so why bother?"

I'm reloading for 8 different AR rifles. All have the bullets seated to mag length. My 300 BlackOut is the only one that doesn't shoot MOA or better at 200yds! I shot a couple .75 groups with a cheap BCA 6.5 Grendel barrel.

To be honest I don't have a clue how far off the lans I am on any of them because they all shoot great at mag length.

 

[Mikecr]

Two serious misconceptions I see here:
1. A need to be close to lands for accuracy
2. That seating depth doesn't matter otherwise

For 'MOA or better', I imagine you could get away with loading bullets upside down..
But for a lot better than that, seating can be the single largest contributor to accuracy.
Either way it doesn't hurt to just go ahead and fully test for best seating.

 

[Havard]

Two serious misconceptions I see here:
1. A need to be close to lands for accuracy
2. That seating depth doesn't matter otherwise

For 'MOA or better', I imagine you could get away with loading bullets upside down..
But for a lot better than that, seating can be the single largest contributor to accuracy.
Either way it doesn't hurt to just go ahead and fully test for best seating.

my biggest doubt or question here was not so much about seating depth in general, but mostly why the group changed when I changed the seating depth, and did I need to adjust my charge to get my group back sub MOA. The problem was induced by me. I failed to check COAL / Mag Length initially. This is a hunting rifle and I should have checked that first. We were late summer and single feeding on the bench, so I didn't care at the time.
I know that a Barnes will typically jump without a problem, so that's why I was scratching my head on this. I will go back through the process of load development with regards to powder charge and use the seating depth required to feed from the mag. I may also try the Hammer Hunter as I'm going back to the beginning.

 

[CaptnC]

Two serious misconceptions I see here:

2. That seating depth doesn't matter otherwise

For 'MOA or better', I imagine you could get away with loading bullets upside down..
But for a lot better than that, seating can be the single largest contributor to accuracy.
Either way it doesn't hurt to just go ahead and fully test for best seating.

I was not saying it doesn't matter. My point is, if you are restricted by magazine length...working out to the lans might not be possible unless you want to run your rifle as a single shot. In my case...6.5 Grendel run through the AR platform, using it as a single shot isnt very desirable.

OP...my thoughts are you've changed the case the percentage of case fill. I'm sure you seen where Nosler load date show a percentage of case fill. So depending on the bullet and whether you are shooting a compressed load...you changed the amount of "open space" inside the case.

I've seen many guys on this site who look for just that...maximum case fill. So once you pushed you bullet deeper into the case you changed that percentage of the case fill.

I'm relatively new at hand loading for accuracy so my degree knowledge is not close to being equal many of the guys here. But seating depth changes more that just the distance to the lans.

 

[L.Sherm]

Just get a wyatts or better yet a Baney box installed, screwing around buying different bullets powder etc will probably cost more than just to get an extended box installed it's not that big a deal.
Problem solved.