My first experience loading 308 for an AR-10

[SWThomas]

So I have a GA Precision GAP-10 that I'm going to start reloading for. I've got plenty of Nosler brass, Mil brass, Black Hills brass, and some headstamped RP. I got some Sierra MK 175g HPBT bullets for punching paper and some Barnes 180g TSX bullets for hunting. I'll load the Barnes bullets later. For primers I got the CCI #34 military primers. I'm planning to use Varget for my loads but I also have some IMR 8208 XBR. I finally got all the gear I needed to load up some test rounds and here's how it went.

I decided to start with the batch of Black Hills brass (which bites be in the ass later). All of this brass has been fired in the GAP-10 so it's formed to its chamber.

- I used my bump gauge and set the sizing die on the Dillon to bump the shoulder back .003-.005. I did everything in accordance with the instructions and sized a batch of 50.

- Next I trimmed all of the brass to 2.005 and deburred/chamfered them. I also use a primer pocket cleaning tool and cleaned out all the pockets.

- While I tumbled the case-lube off, I figured out my seating depth.

- I used a comparator and sorted all the Sierras in groups within .005 of each other.

- I got the GAP-10 out and used a seating depth tool to get me on the lands. The measurement on the tool was 1.643 and the average bullet length on the batch I chose was 1.250. This meant that 2.893 OAL put the ojive of the bullets right on the lands.

- I assembled a dummy round. The neck tension is plenty tight so I did not crimp the bullet. I chambered that assembled dummy round with the force of the bolt and it chambered and extracted just fine. No change in OAL so it wasn't too long.

- Next I checked to ensure it would fit in the magazine, and low and behold, it did not. I was expecting this. I had to seat the bullet deeper to an OAL of 2.827 to get it to fit in the magazine. So the comparator sorting and seating tool were pretty much a waste of time. But they'll come in handy when I load something for a bolt rifle.

- Next I get the Dillon set up for large primers and get it loaded up with 50 of the CCI #34s. I got the Varget and the powder trickler ready and got the brass out of the tumbler.

Unfortunately, this is where I stopped. I found out the hard way that Black Hills crimps their 308 brass and I couldn't seat any primers. The Noslers and RP brass are not crimped but I ran out of time. I haven't gotten a tool to swage pockets yet so I couldn't go any further. But once I do I think I got it all figured out.

Is there anything you see here that I did wrong or have any advice for a beginner?

 

[TBH]

I believe you will have to resize full length for reliability.

 

[docsleepy]

You can get rid of those crimps several ways, just pick one:

1. The Lee case mouth bevel tool will take the crimps out quite easily

2. Or you can use a large drill bit, adroitly done just to create a bit of a bevel

3. Even a pocketknife will do it.

Yep, loading for a semiauto with a magazine is quite different from a bolt. By the way, I would recommend that you full length size (not just bump the shoulders) but I can't prove it will make a difference. Either way, setting the shoulders just a very few thou back will make the appearance of head separations take more reloads, a good thing.

 

[SWThomas]

The die I'm using is a full length sizing die. I'm sizing this way based on some recommendations and a lot of reading. I guess I'll find out if I need to size deeper when I get to run some of these.

 

[Hungry1]

Is there anything you see here that I did wrong or have any advice for a beginner?

I'm reloading 7.62x51 for a M1A. I've started using a FL, RCBS X Die. It is supposed to help extend case life.

Haven't used it enough to tell yet. Only three loads on the brass.

Good Luck

 

[docsleepy]

SWThomas -- OK, didn't realize you were using a FL sizing die. That is great. Just a few thousandths (2 or 3 is plenty) is all you need.

Also, you can just wipe off the lube; no need to tumble them.

Did you use a tool to remove any flashing from the inside primer hole on the inside of the case? RCBS makes a tool and for really high quality rounds, I give it one turn around. Usuallky it finds nothing, but occasionally a big burr is removed.

 

[docsleepy]

For an AR, unless you have some fancy match barrel and have the ability to seat so the bullets can be set very near the lands (and enormous experimentation would be needed to figure out optimal....) you will probably find with Sierra bullets that the comparator is unnecessary. Just set the COAL so that you can comfortably fit within the magazine and of course, chamber the round.

What I think is probably more important is to check your actual seating results - some times I have been surprised to find that there was more variation than expected. up or down 3 or 4 thous probably doesn't matter in an AR, but 10 thou off is not OK, and a difference in neck tension in an oddball case, or how you pulled the lever, can sometimes do that.

This is assuming you want really high quality cartridges. If all you want is bang bang stuff, this is way way overkill.

 

[mtrmn]

The X die DOES NOT necessarily extend case life. You will still get case head separation etc on about the same schedule. What it DOES do is reduce your case trimming. You trim once at the beginning and your brass should not need trimming anymore.

Just "bumping the shoulder" on brass that was not fired in your AR10 will most likely not get good results. You need to FL re-size and use a case gage to make sure your rounds meet spec. All these little accuracy tricks and extra PITA steps that will make a difference on bolt guns will likely not make any visible difference on semiautos other than compromise reliability.

I personally use small base dies because I'm feeding multiple AR's and I need all my ammo to fit all my guns. Each gun does have it's pet load that will do subMOA, but my bulk ammo shoots less than 1.5 MOA in all my guns. A couple of my ARs have been proven to need small base dies to be 100% reliable. YMMV

I use the JP case gages because they are the only ones I know of that are made with actual chamber reamers. That means the interior of the case gage is tapered just like your ammo and chamber. All the other brand case gages I know of are simply drilled to a certain depth to measure headspace length. The interior sidewalls of these gages are STRAIGHT, not tapered--not shaped like your chamber. So a bulged shoulder or something would still pass the "plunk test" in one of these gages, but it will not chamber in your gun.
http://www.jprifles.com/1.5.1.2_maint.php
I load thousands of rounds of 223 and 308--every one drops in this gage before it goes in the ammo can.

As others said, just load your ammo to the max length that will work in your mags and forget about it. All that "distance to the lands" mumbojumbo will turn your semiauto into a single shot.

 

[Rule3]

For reaming your primer pocket crimps you can use the Hornady reamer. Either by hand or take the bit and chuck it in a drill..I lock the drill in a vise and can process the pockets. I think it is better metal than the Lyman version.

There of course is the Dillion or RCBS bench mount swager if you have a lot of them to do and spend the money.

http://www.midwayusa.com/product/176759/hornady-primer-pocket-reamer-tool-large

 

[SWThomas]

mtrmn,

Please re-read my post. All of this brass was fired in the gun I'm reloading for. And I am full length resizing, just not pushing the shoulder much.

 

[Walkalong]

If you are moving the shoulder .003 to .005 from it's fired condition, you are moving it too much IMO, even for an auto loader. Try for .002 to .003 max. .005 is a lot from the once fired condition.

 

[SWThomas]

I'm doing it this way based on recommendations and the instructions that came with the bump gage.

 

[Walkalong]

Keep an eye out for internal ruts.

http://www.thehighroad.org/showthread.php?t=734058

 

[SWThomas]

I fired them off today. All 50 fed and fired perfectly. Accuracy was best between 42.5 and 44.5 grains. I'm gonna load up some more and see if I can narrow it down a little more.