300 WSM AR10

[C-130 Dude]

I didn't have any problems. I had reloaded bunch of commercial 308 brass with 2 grains less than the listed max for 150 bt-fmj for testing 45.1 and 2.700 for COL for ease of feed. So they might be approaching 60K psi. chrono speed was just over 2800 fps.

The ejections started out at @ 2 o'clock so I opened the gas block just a little to get right about 3. I've also been lucky with non adjustable gas blocks and just put in rifle length springs for what ever the caliber

I've never have built an AR with problems because I use the best forgings with the latest style of barrel nuts and free float m-lock type hand guards.

In the past I built some piston guns with Superlative gas blocks and the adjustment aren't the best.

I use a similar recipe, at 45gns. Had 2740fps, 2.750coal, at about 56020. Somewhat warm/hot, but I wasn't sweating too much yet. HA! Your gas pattern looks good. Is this with your loads or with factory ammo? Superlative works if you are patient. I have had a couple of their gas blocks that were not machined right. Gas vent was not up to their spec. Too bad. This entire large frame build problem stuff would be a whole lot easier if they had spec'd it like the AR15. Nuff said, that's my rant for the day.

 

[budlight]

I don't know everything, But I never have built a AR that pierced the primer or required excessive buffer weights. I also never went down the service rifle low pressure road. I never bought factory ammo. I always just use the fast powder dump and a single stage or my electronic powder dump if I am trying for real competition rounds.

I first started out on ar15's with SS match barrels all rifle length gas tubes and I came across an article about pressures inside the barrel at the carbine , mid length, and rifle length gas port holes. So as you see pressure going down requires a bigger gas port hole to cycle the rifle.

So I reasoned, Why not ask the manufacturer to only drill mid length or even carbine sized hole for my rifle length barrel because I am going to be running full powered reloads of mine. It will bleed off less pressure and get higher velocity and not beat the crud out of the buffer weight and parts. You can always make a hole bigger. So I asked for an .078 and it worked wonderfully with light springs and buffer weight. Of course the full auto heavy NB bolt bcg. rifle length 20 inch. So my next barrel I went even smaller with a .073 and it also worked like a champ with a rifle length same .750 micro non adjustable gas block.

I carried the same reasoning over to my AR10 rifle plus 2 inch. please only drill a smaller .081 hole because I am running near flattened primer full powered 308 rounds through it. If it doesn;t work I will send it back. All three of my ar10s work like a champ and I have a non adjustable block on one of them. TAC and CFE 223 are my main powders.

This is just a list of the common gas port hole sizes that barrel manufacturers seem to use.

AR-15 Platform 5.56mm
20"	rifle	5.56		0.0935
20"	rifle	5.56		0.096
20"	rifle	5.56		0.098
16"	mid	5.56		0.078
16"	mid	5.56		0.081
16"	car	5.56		0.0625
16"	car	5.56		0.065

18"rifle 0.308 0.0960
18"car 0.308 0.0635
16"mid 0.308 0.078
16"mid 0.308 0.081
16"car 0.308 0.07
16"car 0.308 0.073
16"car 0.308 0.076
20"rifle 0.308 0.0935
20"rifle 0.308 0.096

 

[bamban]

I don't know everything, But I never have built a AR that pierced the primer or required excessive buffer weights. I also never went down the service rifle low pressure road. I never bought factory ammo. I always just use the fast powder dump and a single stage or my electronic powder dump if I am trying for real competition rounds.

I first started out on ar15's with SS match barrels all rifle length gas tubes and I came across an article about pressures inside the barrel at the carbine , mid length, and rifle length gas port holes. So as you see pressure going down requires a bigger gas port hole to cycle the rifle.

So I reasoned, Why not ask the manufacturer to only drill mid length or even carbine sized hole for my rifle length barrel because I am going to be running full powered reloads of mine. It will bleed off less pressure and get higher velocity and not beat the crud out of the buffer weight and parts. You can always make a hole bigger. So I asked for an .078 and it worked wonderfully with light springs and buffer weight. Of course the full auto heavy NB bolt bcg. rifle length 20 inch. So my next barrel I went even smaller with a .073 and it also worked like a champ with a rifle length same .750 micro non adjustable gas block.

I carried the same reasoning over to my AR10 rifle plus 2 inch. please only drill a smaller .081 hole because I am running near flattened primer full powered 308 rounds through it. If it doesn;t work I will send it back. All three of my ar10s work like a champ and I have a non adjustable block on one of them. TAC and CFE 223 are my main powders

AR-15 Platform 5.56mm
20"	rifle	5.56		0.0935
20"	rifle	5.56		0.096
20"	rifle	5.56		0.098
16"	mid	5.56		0.078
16"	mid	5.56		0.081
16"	car	5.56		0.0625
16"	car	5.56		0.065

18"rifle 0.308 0.0960
18"car 0.308 0.0635
16"mid 0.308 0.078
16"mid 0.308 0.081
16"car 0.308 0.07
16"car 0.308 0.073
16"car 0.308 0.076
20"rifle 0.308 0.0935
20"rifle 0.308 0.096

I am doing a 223 Garand barrel for an older gentleman. Using QL chamber pressure simulation for the 556 and M72 to figure out the pressure for the 223 gas port hole. He is a welder he will modify the extractor, ejector is fine as it were.

 

[Citified]

This thread has become very informative with regard to the gas port size. I personally have never run into a pierced primer in 9 builds but then I don't run them as hard as some do. So far, with 223. 300 BO, 6.5 CM and .308 all is good. I am by no means an expert but it is nice to shoot from 110 to 220 grains without issues. Almost all of mine are 16 to 20" barrels though.

 

[C-130 Dude]

I don't know everything, But I never have built a AR that pierced the primer or required excessive buffer weights. I also never went down the service rifle low pressure road. I never bought factory ammo. I always just use the fast powder dump and a single stage or my electronic powder dump if I am trying for real competition rounds.

I first started out on ar15's with SS match barrels all rifle length gas tubes and I came across an article about pressures inside the barrel at the carbine , mid length, and rifle length gas port holes. So as you see pressure going down requires a bigger gas port hole to cycle the rifle.

So I reasoned, Why not ask the manufacturer to only drill mid length or even carbine sized hole for my rifle length barrel because I am going to be running full powered reloads of mine. It will bleed off less pressure and get higher velocity and not beat the crud out of the buffer weight and parts. You can always make a hole bigger. So I asked for an .078 and it worked wonderfully with light springs and buffer weight. Of course the full auto heavy NB bolt bcg. rifle length 20 inch. So my next barrel I went even smaller with a .073 and it also worked like a champ with a rifle length same .750 micro non adjustable gas block.

I carried the same reasoning over to my AR10 rifle plus 2 inch. please only drill a smaller .081 hole because I am running near flattened primer full powered 308 rounds through it. If it doesn;t work I will send it back. All three of my ar10s work like a champ and I have a non adjustable block on one of them. TAC and CFE 223 are my main powders

AR-15 Platform 5.56mm
20"	rifle	5.56		0.0935
20"	rifle	5.56		0.096
20"	rifle	5.56		0.098
16"	mid	5.56		0.078
16"	mid	5.56		0.081
16"	car	5.56		0.0625
16"	car	5.56		0.065

18"rifle 0.308 0.0960
18"car 0.308 0.0635
16"mid 0.308 0.078
16"mid 0.308 0.081
16"car 0.308 0.07
16"car 0.308 0.073
16"car 0.308 0.076
20"rifle 0.308 0.0935
20"rifle 0.308 0.096

Nice data. Many thanks for sharing it! Looks very similar to my experience. You may notice that I differentiate between AR308 (DPMS spec) and AR10 (Armalite spec). As you know, they are different. Specs and such. I state this for folks so they know why I do that. Some parts are interchangeable, others not. I use factory loads to break in my barrels and hand loads from then on. What buffer weights and springs are you using on your AR 308 gun? I shoot mostly 150, 155, 168, and 175 grn bullets now. My main AR308 gun is now using a 20" Criterion m118 profile barrel, .94 or .96 gas hole(can't remember), box stock DPMS bolt carrier with a JP high pressure bolt. I use this bolt because every one of AR308 guns have suffered from pierced primers. Initally thought it may had been primer manufacturer, but changing between Fed, CCI, Win, and a couple of others did not have a difference. Magpul enhanced stock extention. It works well having a .75 in longer length allowing the standard length ar15 buffers to be used and the ramped/tapered ears wrap around the stop pin reducing bcg slamming into the buffer. Using a 5.4oz buffer with an Orange spring. Also the Superlative adj gas block is .750 journal. All this took me almost 1.5 years to completely wring out. Course I had a lot of things going in life since I built this in 2014. Like everyone else, I could have done it quicker if my time was expended different. Looking seriously at going to a .825 journal on my next barrel, sometime this summer. Well that's my setup. Don't think I ever actually wrote it down. Hope it helps some folks out there. Stay safe and have fun.

 

[bamban]

Unfortunately, there is not standard across the large frame AR. I have a hybrid lower that is AR10 upper compatible, but takes DPMS magasine. It was made in Temple, TX by a company that I have no idea if it is still in existence.

 

[C-130 Dude]

Unfortunately, there is not standard across the large frame AR. I have a hybrid lower that is AR10 upper compatible, but takes DPMS magasine. It was made in Temple, TX by a company that I have no idea if it is still in existence.

Standards, or the lack on large frame. Why couldn't they just standardize like the ar15? Too easy i guess. My biggest problem now is replacing my handguard. Lo profile. High profile. Hassle. I have been looking for a 15in, AR308/10 size, no pictanny top rail, mloc, dpms low profile. These are hard to find. I did find a couple, but at 275+. Ouch! But they are carbon fibre.......JP makes a sweet one, but real$$$. Keep looking.

 

[budlight]

I totally pieced these rifles together from a variety of manufacturers. So I don't know or recall specifics about the spring and weight. Barrels from one place, hand guards from another, forged upper and lower from another, fire control kit from another. The only part that bit me was the "Bolt Catch Release" So I took pictures and sent it to the vendor and they just couldn't understand why the small tip didn't work. It made the maiden voyage a single shot that couldn't hold the bolt open.

I found the wider tip somewhere.

24 inch SS 308 scope is a 4-48 power 65mm objective. So I can get on varmints faster at long ranges. The Speer 125 gr TNT can really red mist critters with Accurate 2460 down loaded to 3200 fps 48.8


LOL, your picture of a C-130 reminded me of why I hated AF guys. We had to go some where quick so they sent us over to catch a ride on a c-130. They had us sitting on cargo nets and gave us this bubble gum looking stuff for hearing protection and we took off. The rear door couldn't shut and seal, we were all freezing to death and the bastard AF guys had fur parkas and gloves and they were laughing. It only had a out house on the rear drop door and the flight was something like 14 hours. We should have kick all their asses and taken their coats.

 

[budlight]

This AR10 lower has the threaded bolt catch pin. I wish that some ar15 manufacturer would pick up on that. Pressed pins just suck although I've gotten good using electrical tape on the jaws of a water pump adjustable pliers. That way you don't scratch the anodized black finish squeezing the pins in

 

[C-130 Dude]

I totally pieced these rifles together from a variety of manufacturers. So I don't know or recall specifics about the spring and weight. Barrels from one place, hand guards from another, forged upper and lower from another, fire control kit from another. The only part that bit me was the "Bolt Catch Release" So I took pictures and sent it to the vendor and they just couldn't understand why the small tip didn't work. It made the maiden voyage a single shot that couldn't hold the bolt open.

I found the wider tip somewhere.

24 inch SS 308 scope is a 4-48 power 65mm objective. So I can get on varmints faster at long ranges. The Speer 125 gr TNT can really red mist critters with Accurate 2460 down loaded to 3200 fps 48.8


LOL, your picture of a C-130 reminded me of why I hated AF guys. We had to go some where quick so they sent us over to catch a ride on a c-130. They had us sitting on cargo nets and gave us this bubble gum looking stuff for hearing protection and we took off. The rear door couldn't shut and seal, we were all freezing to death and the bastard AF guys had fur parkas and gloves and they were laughing. It only had a out house on the rear drop door and the flight was something like 14 hours. We should have kick all their asses and taken their coats.

Must have been a good while back. We stopped using that gum, it didn't work-someones idea of cost saving...Imagine what it would be like in that aircraft on 20+ hour missions with aerial refuling. No ending in sight. The outhouse is the norm. I hear they a flusher now. The old days. Your gun looks nice. Most of these large frames turn into some sort of Frankengun if you keep them long enough.

 

[cohunt]

AR's require a different style of shooting to be accurate--- especially light weight ones.

You'd be surprised how much muzzle jump a 16" 308w 5.5 pound AR has without a brake.

I shoot my 7rm and 300wsm bolt guns free-recoil style on the bench but not my ultralight 308w ar.


I toyed with getting a 300wsm upper from kak a few years ago, but after some research I decided to pass for now. I'm not a fan of "proprietary" parts....been there, done that.

 

[C-130 Dude]

AR's require a different style of shooting to be accurate--- especially light weight ones.

You'd be surprised how much muzzle jump a 16" 308w 5.5 pound AR has without a brake.

I shoot my 7rm and 300wsm bolt guns free-recoil style on the bench but not my ultralight 308w ar.


I toyed with getting a 300wsm upper from kak a few years ago, but after some research I decided to pass for now. I'm not a fan of "proprietary" parts....been there, done that.

I don't like proprietary parts either. Too limited results. My AR308 is 14 lbs. I currently use a M4-72 muzzle break from Precision Armament. It's a bit loud on folks shooting next to me, sorry. I would gladly use a can if they paid for it. HA!

 

[cohunt]

I don't like proprietary parts either. Too limited results. My AR308 is 14 lbs. I currently use a M4-72 muzzle break from Precision Armament. It's a bit loud on folks shooting next to me, sorry. I would gladly use a can if they paid for it. HA!

Yea-- a muzzle brake on a 14 pound ar308 vs a 5.5 pound one ---2.5x the weight difference ( that m4-72 is a really good brake too) -- I almost have to run mine with a brake or a suppressor otherwise the muzzle jump/flip gets pretty crazy. If I shot it a lot I'm sure I could get used to it, but its so different from anything else I have. -- lots of carbon fiber, titanium, ultralight optics, lightened alum parts. I could have gone with a slightly lighter weight profile barrel but I was afraid of too much barrel whip/harmonics.

 

[C-130 Dude]

Yea-- a muzzle brake on a 14 pound ar308 vs a 5.5 pound one ---2.5x the weight difference ( that m4-72 is a really good brake too) -- I almost have to run mine with a brake or a suppressor otherwise the muzzle jump/flip gets pretty crazy. If I shot it a lot I'm sure I could get used to it, but its so different from anything else I have. -- lots of carbon fiber, titanium, ultralight optics, lightened alum parts. I could have gone with a slightly lighter weight profile barrel but I was afraid of too much barrel whip/harmonics.

If you use it for lots of practice, you never really get used to it. I would like a can though. Make everyone happy.