Question on bullet seating length and powder charg

[aquinas]

Hey guys,

Glenn Zediker says in his "Handloading for Competition" book to back a powder charge off by 1/2 grain when you seat the bullet to the lands. But he doesn't say when to increase the powder charge back to normal.

Do you always keep it 1/2 grain under?

If it shoots well touching the lands, do I increase by .01 grain increments until I either see pressure signs or am back to full load?

How do you guys do it?

I loaded 50 rounds in 10 round increments with the first 10 touching lands, then decreased the seating depth by .005 on each 10 after that. I'll see where that gets me.

I'm doing this for NRA service rifle competition.

 

[2Shots]

Re: Question on bullet seating length and powder charg

The reason for backing off was because the pressure will increase with it touching. We usually touch the lands to see how it groups then back off .005 to .010". Touching the lands can sometimes be tricky to shoot reliably. Safer to be just shy. You can look for pressure signs after shooting with them touching and adjust the load from there. You can take a load that shoots with no pressure signs that's .005" off the lands and try that same load jammed into the lands and you can't get the bolt open without a 2x4.

 

[BobinNC]

Re: Question on bullet seating length and powder charg

himaster,

To answer your question fully, I must first ask you a question:

What are you trying to accomplish???

I ask that because, you are going through a bunch of work, for marginal benefit, unless your a dedicated benchrest or f-class competitor.

If your NOT a dedicated benchrest or f-class shooter ponder this:

How come FGMM ammo shoots so accurately in so many different rifles with the bullet NOT seated into the lands?

While thinking that one over, consider:

The first rule of reloading; if your not single loading that is: The rounds you make must function in your rifle i.e. feed from the mag box.

The relationship of your rounds to your mag box is such, that in order for a round to function in your rifle, it must be the less than max length of your mag box or the distance to the lands, which ever is shorter.

So if your lands dictate a COAL of 2.900", and your mag box is 2.850", then approaching your lands is a no go, because the rounds will not function from the magazine.

See what I'm getting at?? Rounds must function first, as a repeater was intended to work, then work on finding your best accuracy from that point.

Varying powder change by .01 grain increments, and varying seating by .005" is generally a waste of good powder and bullet.

Start at the bottom charge, increase by 0.3 or 0.4 grains increments till you find your max charge. COAL? as long as it functions from the max box, go as long as you can. Then find your nodes either by OCW or Ladder tests.

Then if you want to vary your seating depth you can only make your rounds shorter, not longer.

Good luck,

Bob

 

[aquinas]

Re: Question on bullet seating length and powder charg

Good reply, Bob and thanks.

I'm doing it because in service rifle competition, I can load single rounds in slow fire prone at 600 yds. If it gives me an edge, then I'll take it.

I can usually put most of them in the ten ring at 600 in unsupported prone. I want to increase my X count: sometimes out of 20 I'll have 10 X...sometimes its 4. I usually score 192 to 196 out of 200.

And these are shot either out of an AR-10 or AR-15 service rifle configuration.

Your point, however, is well taken. I always do first and best what works in the "real world." And I have some mag length loads that shoot very well...well enough to post the above scores.

 

[aquinas]

Re: Question on bullet seating length and powder charg

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 2shots</div><div class="ubbcode-body">The reason for backing off was because the pressure will increase with it touching. We usually touch the lands to see how it groups then back off .005 to .010". Touching the lands can sometimes be tricky to shoot reliably. Safer to be just shy. You can look for pressure signs after shooting with them touching and adjust the load from there. You can take a load that shoots with no pressure signs that's .005" off the lands and try that same load jammed into the lands and you can't get the bolt open without a 2x4. </div></div>

OK, so you reduce the load and let's say it shoots great with a jump of .005. Do you work the powder charge back up to the previous level or do you keep it reduced?