Reloading for 308 AR gas rifle

[krw]

I am the new owner of a LMT MWS. I have reloaded extensively for 308 bolt guns. I do not care to load for 223 AR's but I will for this 308. I'm not gonna use my lapua brass in it bt have Fed and Win brass. I also have Varget and IMR4064. I planned on putting the LMT on paper with FGGM 168, and want to see how it handles these. I plan n shooting them through the chrono to get an idea on velocity. I know I cant push it with a gas automatic like I do with bolt rifles. How do I know when I am getting all I can out of a gas gun without being to hard on it?

 

[Tx_Flyboy]

ARs are not like older gas guns such as M1 Garands and M14s that have op-rods which can be overstressed.

ARs will handle bolt-gun loads and ask for more.

Unlike bolt guns, you may see ejector/extractor marks on your brass even with light loads...each AR is different and you need to see what urs is like.

I dont shoot 168s, but i shoot 175s, 178s, 185s etc.

My favorite load is

178 AMAX
LC or Win Brass
44.4gr Varget
Tula LRP
2.80

 

[Kamkaze]

ARs are not like older gas guns such as M1 Garands and M14s that have op-rods which can be overstressed.

ARs will handle bolt-gun loads and ask for more.

Unlike bolt guns, you may see ejector/extractor marks on your brass even with light loads...each AR is different and you need to see what urs is like.

I dont shoot 168s, but i shoot 175s, 178s, 185s etc.

My favorite load is

178 AMAX
LC or Win Brass
44.4gr Varget
Tula LRP
2.80

What are you shooting that load out of?

 

[Guest]

I've tested FGMM 168 and 175, Hornady 168 Match BTHP, and Hornady Match 168 amax out of my POF P308.

Consistent .70" groups at 100yds with the FGMM 175's and 168 amax's. Best group was just over 1/2".

I have the pinned 14.5" barrel on my P308. I recently started reloading for it to test 175smk and 178 amax for long distance shooting steel to 800 and maybe 1000.

Shot .43" groups with

1x fired Hornady Match brass FL sized, trimmed, prepped
175 smk
42.5g Varget
CCI LR 200 primers

I just made up loads for OCW test today using above load. Will test Monday.

I also loaded up this load today to test Monday.

1xfired FGMM FC brass
178 amax
IMR 4064
CCI LR BR2 primers
loaded OCW loads today

 

[Guest]

I also have some LC prepped and FL sized cases to test as well with above loads

 

[Guest]

Got to test my hand loads for my POF P308 14.5" AR10 this past weekend from 200-1000 yards. I loaded the same load but with 3 different types of brass all once fired. Hornady Match, FC and LC. I have never shot past 200yds and never shot my new hand loads past 100yds until this weekend.

44.3gr Varget
175smk
CCI BR2
Seated to 2.2265 ogive

The Hornady Match was the first to test and has now become my go to load. By far the best over the FC and LC brass. I chrono the load at 2484. I dialed up a dope card to shoot 200-1000 for the testing. The FC and LC brass was not as consistently accurate as the Hornady Match past 400yds.

We had 12" steel plates setup at 400, 600 and 800 and there was a 24" gong at 1000.

I dialed my dope for 400 (2.3mils) and hit that 12" plate easily. Dialed in for 600 (4.8mils) and repeatedly hit that 12" plate with ease. I then dialed my dope for 800yds (8.1mils) to go for that 12" plate. We had a TISS hooked up to the 12" plate at 800 so we could easily see hits since it was hard to see or hear hits that far out. First shot at 800 the TISS flash went off signaling a hit. I took a second shot and the TISS went off again. I missed the 3rd shot just off the right side of the plate because the wind picked up to between 10-15mph so I had to hold off the left side of the plate and started getting repeated hits again. I hit the 12" plate 6 out of 8 times. I felt really good about the hits because this was the first time I shot past 200 and I've only started reloading less than 2 months ago.

Now I went for the 1000 yd 24" gong. I dialed my dope (12.2mils) and pulled the trigger. First round hit at 1000yds. I missed the next 2 but got back on the gong on my 4th shot.

Really happy my shooting and loads this weekend. Especially out of my short barreled AR10.

Firing Line



1000yd line looking down on firing line

 

[H-D]

Wow, you're a natural!!

 

[Guest]

I wouldnt go that far. Just alot of time and hard work paying off.

I went to my local 100yd range damn near daily over the past 2 months to dial in my load, test seating depth, and chrono. That hard work is finally paying off.

 

[MitchAlsup]

<snip>How do I know when I am getting all I can out of a gas gun without being to hard on it?

ARs will lob the spent cases at 90 degrees to the direction the rifle is pointing when the load is "timed" correctly.
If the case is lobbed out towards the front, the "timing" is late (bullet slow). Too little pressure in the barrel when the bullet passes the gas hole.
If the case is lobbed out towards the back, the "timing" is early (bullet to fast). Too much pressure in the barrel when the bullet passes the gas hole.

So what you are looking for in developing a load is an accuracy node* that lobs the spent cases out of the port at 90 degrees.
(*)An accuracy node is a reloading recipe that coincides with the barrel harmonics and prints tiny groups. See Ladder method, Audette, and Optimal Charge Weight.
The trick with a gas gun is to find the powder that gets the accuracy node lined up with the gas port so all 3 variables are simultaneously optimized.

 

[sakobob]

ARs will lob the spent cases at 90 degrees to the direction the rifle is pointing when the load is "timed" correctly.
If the case is lobbed out towards the front, the "timing" is late (bullet slow). Too little pressure in the barrel when the bullet passes the gas hole.
If the case is lobbed out towards the back, the "timing" is early (bullet to fast). Too much pressure in the barrel when the bullet passes the gas hole.

So what you are looking for in developing a load is an accuracy node* that lobs the spent cases out of the port at 90 degrees.
(*)An accuracy node is a reloading recipe that coincides with the barrel harmonics and prints tiny groups. See Ladder method, Audette, and Optimal Charge Weight.
The trick with a gas gun is to find the powder that gets the accuracy node lined up with the gas port so all 3 variables are simultaneously optimized.

your bullet lobbing idea is not always the true read of the rounds psi.
i have a 308 gasser that would throw the empties to the 1 o'clock because of to much psi, they where moving the
bolt to fast and it would hit the empty as it bounced off the buffer very hard and push the empties forward.
and when i started to reload for it when the psi went down the brass would go to the 3-4 o'clock.

krw , just as with a bolt gun your brass will tell you what you need to know. load a few light loads (starting charge weights )
and pay attention to the fell of the gun ,the bolt movement will have a nice smooth feel to it and shouldn't slam back into your shoulder
because the buffer is being hammered back buy the bolt speed. i highly recommend a adjustable gas block(not the 3 or 4 position ones) that has a full
range of adjustment.