308 loading process for bolt guns vs gas guns?

[Swift]

Gonna start loading my first batch for development with my new LAR308 and have minimal experience reloading for a gas gun. Done a few hundred 223 but that's it.

Are there any differences that I should be aware of? I know COAL becomes an issue because it's mag fed. Should I stick to SAAMI specs? What's the easiest way of getting an accurate measurement of my chamber so I can trim/size accordingly? Never did it with my bolt gun but I want to take extra caution since I am no longer in charge of ejecting and loading rounds and don't want to be prying expensive brass out of the chamber.

I'm going to be using 155gr Scenars, Lapua brass, CCI primers and ~46gr Varget out of a 20" 12 twist barrel to start. I hope to end up around 2750-2775 fps. Is this feasible or am I dreaming? Being a stout load and an autoloading rifle, how long would quality brass hold up?

Any other tips/tricks/hints are welcome. Just wanna make sure I don't blow my upper and/or my face into oblivion.

 

[terrance250]

Re: 308 loading process for bolt guns vs gas guns?

As in all reloading start low & work your way up watching closely for pressure signs (cratered primers, & ejector swipes are what I usually run into around max).

My precision gas gun loads still get case/bullet sorting, seating done with a comp seater to reduce run-out, flash holes de-burred, & precision thrown charges. I almost always seat to mag-length, and you can play around with neck tension as well. I tend to lean towards the tight side when it comes to neck tensions to prevent a bullet from getting rammed deeper into the case mouth during feeding.

As hard as it is to stomach sometimes, just remember,the hottest/fastest load is not necessarily the best.

 

[Shady_Jay]

Re: 308 loading process for bolt guns vs gas guns?

I recommend sticking to factory length. Some people crimp the rounds but I have thousands of un-crimped rounds down the tubes with no problems. Other than that, I develop loads for a gasser the same as a bolt. I FL size everything for both.

 

[desertHK]

Re: 308 loading process for bolt guns vs gas guns?

As mentioned above, stick to SAAMI specs and FL your case to get reliable feed. I don't crimp mine.

 

[Swift]

Re: 308 loading process for bolt guns vs gas guns?

Awesome. Can't wait to get it goin. Do you guys use the same dies as you do with your bolt guns?

 

[turbo54]

Re: 308 loading process for bolt guns vs gas guns?

My only autoloader experience is with a DPMS SASS. In the beginning, I had a couple issues with stuck rounds in the chamber because my bodies weren't sized quite enough.

I would recommend you take a bit of time making sure your sizer is doing what it needs to do.

Take your upper off the lower, drop a sized case (no primer, powder or bullet) down into the chamber. Use your finger to push the case into the chamber with about one pound of foce. Tip the upper muzzle up. Does the case drop right out? No? NOT SIZED ENOUGH

Test fit several cases this way to ensure you're sizing enough.

You will certainly be limited by magazine length in regards to COAL. If you want to play the single loading game, the same method mentioned above (only with an unprimed, uncharged case with a bullet seated) works well to find the "on-lands" COAL for that bullet in that rifle. Seat the bullet .010" deeper for each test fit until it doesn't "stick" in the throat.

 

[MitchAlsup]

Re: 308 loading process for bolt guns vs gas guns?

The reloading process for an autoloader is a little more complicated than for a bolt gun. You are not only looking for an accurate loading, but a loading that cycles the action "properly". Properly means with enough cycling pressure but not with excessive cycling pressure.

When the autoloader is cycling under pressure loads, it will often eject them forward. And when it is cycling loads with excessive it will often throw the cases backwards. Finding an accurate load that drops the cases in a neat pile off your right sholder is the task at hand.

So, reloading for an autoloader might be forced to find a powder (or primer, or bullet shape) that finds that happy medium of great accuracy and perfect cycling at the same time.

 

[bcrich]

Re: 308 loading process for bolt guns vs gas guns?

Save that good brass for the bolt gun, that semi is gonna beat the crap out of it! post your results, those components are an awesome combination.

 

[mac37]

Re: 308 loading process for bolt guns vs gas guns?

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Some people crimp the rounds but I have thousands of un-crimped rounds down the tubes with no problems</div></div>

No need to crimp. There is a section in the Sierra Reloading manual that is a must read - "Reloading for Semi-Autos and Service Rifles".
PM me your email and I'll send you the .pdf