AR vs 223 bolt gun ?

[Rdlningcltchdmpr]

Boulderdash ! You only need one good eye ! Forget the 223/556 anyway, the new 6mm ARC is now out ! Hornady yeah !

 

[Metal God]

6mm ARC is now out ! Hornady yeah !

I'm so exited about this cartridge .

 

[Rdlningcltchdmpr]

Me too, also excited about spring. I wet my plants .

 

[std7mag]

Metalgod,

We both know that your aware of the differences in 223/5.56.

Leade, freebore, mag length, etc...

Lets not forget, the differences in pressure are measured differently.

I wouldn't be surprised to see NATO cartridges reaching 60,000-63,000 psi.

I don't know of anyone running an RSI Pressure Trace on one though.

 

[rebs]

Thank you guys for all the information

 

[2506]

Without modification to the magazine that is exactly correct. However if you cut a window in the front of the magazine I have loaded to 2.370" OAL. Limitation becomes the lower mag well. I use a steel magazine, and only cut the window for 5 rounds. With a sled there is no lenth limit as long as you want single loading.
View attachment 1183248

Yes, I also know a guy that put a 350 Chevy V8 in a Chevy Vega in 1972 when I was in high school. LOL

 

[Laurie]

Lets not forget, the differences in pressure are measured differently.

I wouldn't be surprised to see NATO cartridges reaching 60,000-63,000 psi.

Yes and yes. CIP max for 223 / 5.56mm is 4,300 bar / 62,366 psi. There are differences though between SAAMI and CIP chamber pressure measurement systems that may mean they're not completely compatible.

We have a fair few ARs in the UK, but those in private ownership are manually operated, ie straight-pulls. Semi-automatic rifles other than .22 rimfires were moved into the UK Firearms Acts 'Section 5' (prohibited weapons) classification in 1989 after the Hungerford mass shooting. Even with much extended and ergonomic side operating handles, these rifles are pretty good alfresco pressure gauges as shown by how hard a tug it takes to get primary extraction and the case + bolt group moving. You can literally feel every 0.2gn charge weight increment's pressure rise once you get past the point where QuickLOAD says you're hitting 50,000 psi. Above a QL calculated 55,000 psi it becomes hard work. Then firing out of the box 5.56mm Nato 62gn military spec ammo is another thing - you can do it, (and many do), but it is really tough.

(That is in rifles with suitable chambers of course, either 5.56mm or more commonly Wylde types.)

 

[Uncle Ed]

Laurie

Are you saying British AR shooters look like crabs with one arm bigger than the other?

Gives new meaning to primary extraction and loosing your sight picture.

 

[jelenko]

I tried a Lantac straight pull assembly in my upper. They've got an extension on the bolt handle so you don't have to reach forward and the handle is at a good angle. Even with middle of the road load, there's a definite 'tug' to start the bolt opening.

 

[Laurie]

Laurie

Are you saying British AR shooters look like crabs with one arm bigger than the other?

Gives new meaning to primary extraction and loosing your sight picture.

Ha! Ha! A bit like the 'Bullworker' exercise tool for building up the upper arm and torso muscles that were advertised in weekend newspapers when I was a kid. (Did you have this device in the US and if so was it advertised using a cartoon strip that started with Jocks kicking sand into the skinny guy's face on the beach and making off with his girl?)

 

[Laurie]

I tried a Lantac straight pull assembly in my upper. They've got an extension on the bolt handle so you don't have to reach forward and the handle is at a good angle. Even with middle of the road load, there's a definite 'tug' to start the bolt opening.

The British versions mostly have a side-handle upper and a damn great handle on an extension that bolts directly onto the bolt carrier.

 

[jelenko]

Ha! Ha! A bit like the 'Bullworker' exercise tool for building up the upper arm and torso muscles that were advertised in weekend newspapers when I was a kid. (Did you have this device in the US and if so was it advertised using a cartoon strip that started with Jocks kicking sand into the skinny guy's face on the beach and making off with his girl?)

Yep!

 

[searcher]

I have cracked bolt lugs off of several A/R bolts by overloading. These were all on 6.5 Grendels which shave a bit off of lugs which were already inferior to the (relatively) massive lugs on bolt guns. Just look at how much steel you have holding the bolt in place on both actions. And, indeed, there are differences in bolt guns too. Like the difference between a BAT action and that of a Sako Vixen. One can just look at these and pretty much KNOW which one will fail first.

 

[Laurie]

I have cracked bolt lugs off of several A/R bolts by overloading. These were all on 6.5 Grendels which shave a bit off of lugs which were already inferior to the (relatively) massive lugs on bolt guns.

I'd assumed that is why the SAAMI Grendel maximum is a modest 50,000 psi. When people started building 7.62X39mm AR-15s and the US military were experimenting with this cartridge in the platform, I read somewhere that the US Army was dubious about its mechanical viability thanks to the increased case-head area (as per the Grendel of course the pair being directly related) increasing thrust allied to the necessary lug thinning to fit it in. A figure for planned 7.62X39mm bolt replacement was settled on which I remember as 9,000 rounds - but I could well be mistaken on that.

Again, the European CIP agency has set a much higher value than SAAMI for this cartridge, 4,050 bar / 58,740 psi. I use this as my ceiling in QuickLOAD in loading the cartridge for a Howa 'Mini' bolt-gun and have had no issues. (Incidentally, I saw in 65grendel.com that Bill Alexander says QuickLOAD is very inaccurate on the Grendel. It is if you use default values, but I've found it gives remarkably close results to actuals when the inputs are reset for actual cartridge characteristics, especially the fired case 'water overflow' weight.)

 

[mousegunner]

Without modification to the magazine that is exactly correct. However if you cut a window in the front of the magazine I have loaded to 2.370" OAL. Limitation becomes the lower mag well. I use a steel magazine, and only cut the window for 5 rounds. With a sled there is no lenth limit as long as you want single loading.
View attachment 1183248

I did the same with my rapid fire mags to seat my 77s out a little further. I saw where one shooter had a AR mag modified to take 80s, the front was cut down, the rounds were single stacked and the front of the magazine well on the receiver also had a groove modified for the longer 80s. He shot 80s at 300 rapid and shot good but I've almost cleaned the 300 with my cut mags and 77s.

 

[gunsandgunsmithing]

I'd assumed that is why the SAAMI Grendel maximum is a modest 50,000 psi.

If you calculate bolt thrust, the max psi between the 223 and grendel are relative to one another.
You may know but google can help with rifle bolt thrust calculations. If you adjust max psi of both with the percentage of area of each case id, the two are pretty much exactly the same. IOW, max pressure for the Grendel was adjusted down due to the increased bolt thrust of the lager diameter case..proportionately.