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?

 

[1slow01z71]

On the 223/308 auto loaders youre wasting your time measuring the lands for a mag fed cartridge. Your COL will be short enough to fit in the mag that you wont hit the lands. Make sure you've got proper neck tension for when the cartridge gets slammed into the chamber so you COL doesn't elongate. Go with a Dillon super swage, I love mine and then youll be able to buy mil surp 5.56 and 7.62 LC brass for cheap(ish). The LC brass is also pretty uniform so Ive had good luck with it for pretty good accuracy and its consistent year to year.

 

[scudzuki]

I chamfer primer pockets to remove the crimp on 5.56/.223 and 7.62/.308 brass using the same tool I use to chamfer case necks.
A small chamfer removes the crimp without making the primer pocket any larger or the case any weaker.

Joe

 

[SWThomas]

I chamfer primer pockets to remove the crimp on 5.56/.223 and 7.62/.308 brass using the same tool I use to chamfer case necks.
A small chamfer removes the crimp without making the primer pocket any larger or the case any weaker.

Joe

Thanks for the tip. I may try that.

 

[SWThomas]

On the 223/308 auto loaders youre wasting your time measuring the lands for a mag fed cartridge. Your COL will be short enough to fit in the mag that you wont hit the lands. Make sure you've got proper neck tension for when the cartridge gets slammed into the chamber so you COL doesn't elongate. Go with a Dillon super swage, I love mine and then youll be able to buy mil surp 5.56 and 7.62 LC brass for cheap(ish). The LC brass is also pretty uniform so Ive had good luck with it for pretty good accuracy and its consistent year to year.

You got any tips on checking proper neck tension? I smacked the dummy round several times pretty hard on the bench and it had no affect on the OAL.

 

[1slow01z71]

Measure the neck diameter then seat the bullet and remeasure. That will give you your neck tension. The general rule is .003 but Ive gotten away with .002. Press the bullet on your bench with 20-25#s of force. If your COL doesn't get smaller youre good. Ill also run mine through a mag into the chamber 10 times on a new load just to check. Ive begun using a Lee FCD on my autoloader stuff just to keep neck tension constant after multiple reloads on the same brass. After 6-8 firings the necks get a little weaker on my hot 223 loads. I don't anneal as Id rather just buy new brass since mil surp is relatively cheap.

 

[elfster1234]

I have found this not to be true. When reloading for my LMT I'm able to reload damn near every single bullet to mag length BUT for the sierra gameking... not only is well under mag length, but well under recommended coal as per the sierra manual. I always check every single bullet loaded for my LMT just to be on the safe side. I developed this thread to help show others what I do when reloading for my AR's and I hope it helps rather than me explaining it all here:

http://www.snipershide.com/[email protected]

On the 223/308 auto loaders youre wasting your time measuring the lands for a mag fed cartridge. Your COL will be short enough to fit in the mag that you wont hit the lands. Make sure you've got proper neck tension for when the cartridge gets slammed into the chamber so you COL doesn't elongate. Go with a Dillon super swage, I love mine and then youll be able to buy mil surp 5.56 and 7.62 LC brass for cheap(ish). The LC brass is also pretty uniform so Ive had good luck with it for pretty good accuracy and its consistent year to year.

 

[1slow01z71]

Well yeah if you load the fat ass ogive GKs haha. Guess I shoulda been more thorough in my post. On 223 Ive never found a bullet I can hit the lands at mag length, on 308 I haven't either but I don't load game kings. Amaxs do work on animals just fine and theyre cheaper. Ive only loaded, amaxs, SMKs, bergers and some noslers. The noslers were only in my ar15.

If you don't have the hornady kit you can cut a slit in the case mouth of one of your fired brass and chamber it. That will give your lands measurement. Just be sure to pull the extractor on your BCG and pop the bullet out from the muzzle side with a cleaning rod. I like the hornady kit because it doesn't require my to pull the extractor on the bolt. There are a million different ways to measure the lands on your rifle though so pick what makes you happy. If you don't mind spending the money the hornady kit is awesome.

 

[MO_Boy]

Well yeah if you load the fat ass ogive GKs haha. Guess I shoulda been more thorough in my post. On 223 Ive never found a bullet I can hit the lands at mag length, on 308 I haven't either but I don't load game kings. Amaxs do work on animals just fine and theyre cheaper. Ive only loaded, amaxs, SMKs, bergers and some noslers. The noslers were only in my ar15.





I am reloading Sierra 165 HPBT Gamekings for my LMT and if I would have went by the OAL from Sierra,, they would have jammed bigtime into the lands. I know the B.C. sucks and that these are not a widely used boolit for AR's. I was loading for deer hunting but have found them to be extremely accurate in my rifle. And,,, I can load them with a small jump. Whether that matters or not,, I do not know. I have loaded other Sierra's ( 155palma, 168MK, 175MK, and 165SP Gameking ) and they jump a decent amount. Over .070" if I remember right on the 155's. They do however all shoot well, just not as well as the HPBT Gamekings.

SWThomas: What kind of case lube are you using? I have been using oneshot and not tumbling afterwards. Hope I have not made a mistake,, I have a decent amount loaded up.

MO Boy

 

[bruddah]

I have found this not to be true. When reloading for my LMT I'm able to reload damn near every single bullet to mag length BUT for the sierra gameking... not only is well under mag length, but well under recommended coal as per the sierra manual. I always check every single bullet loaded for my LMT just to be on the safe side. I developed this thread to help show others what I do when reloading for my AR's and I hope it helps rather than me explaining it all here:

http://www.snipershide.com/[email protected]

Thanks for the reference. I'm going to check it out right now.

 

[SWThomas]

Well yeah if you load the fat ass ogive GKs haha. Guess I shoulda been more thorough in my post. On 223 Ive never found a bullet I can hit the lands at mag length, on 308 I haven't either but I don't load game kings. Amaxs do work on animals just fine and theyre cheaper. Ive only loaded, amaxs, SMKs, bergers and some noslers. The noslers were only in my ar15.





I am reloading Sierra 165 HPBT Gamekings for my LMT and if I would have went by the OAL from Sierra,, they would have jammed bigtime into the lands. I know the B.C. sucks and that these are not a widely used boolit for AR's. I was loading for deer hunting but have found them to be extremely accurate in my rifle. And,,, I can load them with a small jump. Whether that matters or not,, I do not know. I have loaded other Sierra's ( 155palma, 168MK, 175MK, and 165SP Gameking ) and they jump a decent amount. Over .070" if I remember right on the 155's. They do however all shoot well, just not as well as the HPBT Gamekings.

SWThomas: What kind of case lube are you using? I have been using oneshot and not tumbling afterwards. Hope I have not made a mistake,, I have a decent amount loaded up.

MO Boy

Dillon case lube.