Major Pf In A Standard Ar Upper

[George]

Tommi, the low SAAMI ratings for the 30-30 in the Speer book are due to the possibility of high pressure ammo being used in an older gun made from mild steel. The 30-30 is actually capable of HIGHER pressures than the 7.62x39 because it's case capacity is 10 grains greater and it case construction is equal in strength. SAAMI won't rate commercial ammo above 42000CUP for the 30-30 due to the existence of older guns made less robust than they are today. You can load as hot as you want if you have a strong gun in 30-30 (like I do)

Thanks for the images Sako. The VV powders seem to keep the primers nice and pretty. Would like to see a tight closeup shot of the case head/case base from the side in real good light to see if there is any indication of impending case head separation. This is a shiny band just above the extractor groove and will manifest itself after a couple of firings if the load is too hot for a bottleneck rifle cartridge. I would be interested in seeing closeups of this area of cases that are at least 3x fired to see if this is happening.

[Carlos]

The primers on the fired casing pictured above don't seem to show much pressure at all; certainly not excessive pressure.

Perhaps this has to do with proper powder selection and the use of high quality brands like Vihta Vouri, Lapua and Norma?

Also, several rifles in this chambering feature longer barrels than 16" - including some Valmets, Russian Saigas and various long barreled AK variants.

[Sako92S]

If I need to rate used cases, my choices will be in this order:

1. Lapua berdan case year model 97, 98 (best material so far)

2. VPT 77 Finnish military berdan case (do not use year 78 cases in any circumstanses, they are weak material)

3. Lapua commercial boxer case

4. Sako commercial boxer case (hand picked)

5. Sellier Bellot commercial boxer case

Biggest capasity has Sellier Bellot but it can be reloaded only maximum twice.

I'll try to take some close up pictures tomorrow.

[slowsure]

I have been able to make major in 6.8 SPC.

AR Platform

130gn Sierra

2490ish FPS

20in Barrel

Load is compressed and starting to see some primer flattening...This is at the top of the ladder for me. But it makes major

The only reason I started into the major 6.8 was so many said it should'nt be done.

I dont shoot enough USPSA 3-gun matches to actually see any advantage in shooting a major rifle, most of my 3-gun shooting is some sort of time-plus scoring.

With the right compensator and in the hands of a skilled shooter, I believe major would be an advantage for sure.

[Religious Shooter]

What powder, charge weight, cases, primers, etc. did you use?

Or are you going to be a tease?

[slowsure]

Sorry...no tease...just the facts

6.8 SPC

31.4gn of AA2520 Powder

Once fired Hornady small primer case

WSR primer

Sierra 130 "Flat Base"

Loaded to 2.275 OAL

2488 FPS@ 10ft.

As allways YMMV. Reduce by 10-15% and work your way up.

The Sierra bullet has a flat base and is key in allowing enough case volume for powder and still fit in AR mags.

I also load a flat based 130gn Remington bullet. The Remington bullet is shorter in length and allows just a little more case volume. They are also cheaper

[bigbrowndog]

It makes it but just barely, what were your chrono conditions, ALT., Humidity, Temp. etc.

I know I would not feel comfy going to a match knowing that i'm giving up magazine capacity, for 3+ points over the minimum allowable for major PF. As I said earlier, 10pts over is much easier for differences in chrono location, and environmental differences.

I believe the proposed numbers were pretty much the same, as your results. The catch was it didn't do it(make major) significantly.

Trapr

[George]

Ah, AA2520, one of the culprits when I was testing how hot I could push the 30-30 for hunting. The other was WW748. I love AA2520 for heavy .223 loads (77 & 80gr) in my High Power AR, but never felt it was the shjt compared to Varget for stability, nor a contender in heavier calibers. I use AA2700 and Varget/RL15 under anything bigger than 100 grains that needs to move fast nowadays.

AA2520 ran with the sun a lot like WW748 and would get a lot hotter, or slower depending on temp. Leave it in the sun and it really revs up. Not what you want in a powder pushing the edge. Have you thought of trying Varget, or RL15 to see if you could do better. A long drop tube can get more of them into a case and they do compress well anyway ;-)

I figure one of the bigger 6mm variants (the Grendel and other 6.5/6.8's) running a 125-130 grainer downrange at 2650+ could/should make major safely with room to spare and bring a pretty flat trajectory to the table to boot if you used a 20" bbl in an AR type platform. Cake and eat it for whoever makes this one work reliably magazine feedwise ;-) It oughta' work a muzzle brake real nice too!

[slowsure]

I thought about Varget as a powder for this app. and I have some for some .223 69gn loads. But I thought the Varget would look like someone trying to stick a porcupine in a 6.8 case. The long drop tube might help, I just need to go do it and see how full the case is.

I do all of my loading on a Dillon 550 and the thought of going to a single stage press is bad (as far as time go's). Also cleaning dumped powder on the 550 is not a pleasure in any way.

Thanks for the tip on AA2520 being temp. sensitive. I did all of my testing in the summer months and should go back and recheck vel's now when its cooler. I suspect slower will be the rule. Like I said before I just wanted to see if I could get to major in 6.8 and I did but havent done much with it.... Now if He-Man class let Major rifle's in to play...I might have looked some more at getting some padding on the PF of this load and shot some He-Man class but .30 cal and up puts the .277 as a no go and thats another thread altogether.

RL-15 might be good too. I will have to do some Quickload work on Varget and RL-15 and try them also.

[Iso-P]

Dear friends on the new continent,

a couple of thoughts since I shoot the infamous and exceedingly dangerous 7.62x39 major in semi-auto standard.

The major loadings loads that we are shooting are made by increasing the bullet weight. As Tommi mentioned above, when you increase the bullet weight that tends also to increase the pf.

I’m not going to comment the .30-30 analogy since I don’t tend to comment things that I don’t know much about.

But 7.62x39 major loads I do know well. I think we have shot around 3000 (per rifle) major loadings with my colleague Mr. Count (sometimes spelled without the “o”). Actually I know around ten Finnish shooters who shoot same kinds of loads and we don’t walk around with bolt carriers sticking out from our foreheads, do we.

My total round count is close to 10,000 in AR47 and I think Mr. Count has shot even more with his Sako M92. Yep, we actually tend to shoot these rifles and sometimes even get some level III medals with them (mostly Mr. Count).

Myself and Mr. Count are able to load major with (around 330 pf on a hotter day from the 18” barrel of my AR47) 150gr lockbase without any signs of excess pressure and as far as I remember the load is safe even according to QuicLoad. My point is that if we can do it, you don't have to count[!] yourself as an intellectual to do it also. You could quote Tommi again.

According to my experiences 7.62x39 has two major disadvantages. Firstly the trajectory of the little bugger is very arched with heavier loads. I still remember the disbelief in the faces of our Nordic friends when I explained how high I have to aim to 300 m (without altering the sights). Let's just say that when the target is completely behind the front post, I can still shoot ‘cause I see the target with my left eye...

Second disadvantage is the recoil, but not quite in the way discussed earlier. Because of the low[!] pressure of cartridge the compensators don't work so well in 7.62x39. With the same secretly designed muzzle brake my .308 Valmet AK is completely recoilless.

Actually the 6.8 major seems pretty interesting since we can get 6.8 HK SL-8 in the old world.

Just my two (euro)cents.

[Alaska98]

Didn't some of the USAMU shooting team use their own .30 cal wildcat to make major? And in the recent USPSA magazine another shooter used what he called a "30 Gremlin AR" to shoot major in a multi-gun match. So it seems like a few are pursuing the effort to have a major caliber cartridge in the AR platform. The 30 Remington AR might have been good enough for me, had they bothered to make a 20 or 25 round magazine.

It just seems like a fine way of developing another barrel/bolt and magazine assembly that I "need" for one of my uppers?

Bruce

[boomfab]

I understand the pursuit of a major PF cartridge out of a standard AR platform.

But I sure as heck love the standardization to 223 in IMGA matches. Having to shoot some oddball 6.8/30 centerfire cartridge to stay competitive would increase ammo costs five fold at least.

[davidwiz]

Didn't some of the USAMU shooting team use their own .30 cal wildcat to make major? And in the recent USPSA magazine another shooter used what he called a "30 Gremlin AR" to shoot major in a multi-gun match. So it seems like a few are pursuing the effort to have a major caliber cartridge in the AR platform. The 30 Remington AR might have been good enough for me, had they bothered to make a 20 or 25 round magazine.

It just seems like a fine way of developing another barrel/bolt and magazine assembly that I "need" for one of my uppers?

Bruce

Same person - Daniel Horner who shoots for the US Army Marksmanship Unit, who developed the cartridge. A previous issue of Front Sight has the details on the cartridge.