7mm Mauser out of an AR-15 ?

[Wolfdog91]

Neat ! Just love all the stuff you can do with AR-15's

[Kosh75287]

It looks like someone went to the trouble to re-invent the .280 British intermediate round, developed for the "bull-pup" EM-2 platform, but for use in the AR-15 platform. Not really a BAD thing, I guess, though magazine capacity will suffer.
I'M wondering if anyone will rechamber an IMI Tavor for this round. Putting this round in a "bull-pup" platform would pretty much make the "re-invention" circle complete.

[Larry Gibson]

Appeared to be a couple hundred +++ if not 300 +++ fps short of 7x57 Mauser cartridge capability and that's with the light weigh 119 gr bullets used. Doubt the cartridge would be that impressive with 139 - 175 gr bullets. Certainly, wouldn't come close to the 7x57s capability.

[376Steyr]

I was wondering how you fit a 7x57 into a AR-15 platform. Turns out it is a 7mm Valkyrie, which is the "equivalent."

[36g]

There was a shortened 7mm Mauser cartridge developed in the 1950s or 1960s that basically took a 7mm Mauser and shortened the brass. I've got some boxes here somewhere. I don't recall what firearm they were intended for though.

[Wolfdog91]

Appeared to be a couple hundred +++ if not 300 +++ fps short of 7x57 Mauser cartridge capability and that's with the light weigh 119 gr bullets used. Doubt the cartridge would be that impressive with 139 - 175 gr bullets. Certainly, wouldn't come close to the 7x57s capability.

He was shooting up to 2966fps on a few of those loads
Same weight range bullets horn days book shows it topping out a 2800 and again these are test loads . No to mention Ed is a speed demon and likes to run as fast as possible with the help of all copper bullets so I can guarantee he's going to be running these much faster



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[Kestrel4k]

How is this a "7mm Mauser in an AR-15" ??

I guess the subsonic 158gr handloads in my .350 Remington Magnum would be "38 Special out of a Remington 660" then.

[Fitz]

Something about a Modern Black Rifle the OLD Timers just can't see anything good with them , And on the other side of the spectrum the Youngsters can't see anything good about beautiful Walnut and Dark blue curvy lines .

I just like them all the old battle axes right up with the new wildcats ,, which the modern sporting rifle has allowed more wildcats than any other type rifle from what I can see with the CNC machining they are logo guns we can all have fun with.

[Texas by God]

I like AR15s.
But their action and magazine size relegate the cartridges that FIT them to ALMOST status.
Every new cartridge is ALMOST a corresponding “old cartridge”
My 6.8 SPC is ALMOST a .250 Savage.
The .30 HAMR is ALMOST a 30-30 Winchester.
The .350 Legend is ALMOST a .35 Remington.
If you load the old cartridges (in strong actions) to the same pressure level as the new AR rounds- the difference gets much wider.


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[Wolfdog91]

I like AR15s.
But their action and magazine size relegate the cartridges that FIT them to ALMOST status.
Every new cartridge is ALMOST a corresponding “old cartridge”
My 6.8 SPC is ALMOST a .250 Savage.
The .30 HAMR is ALMOST a 30-30 Winchester.
The .350 Legend is ALMOST a .35 Remington.
If you load the old cartridges (in strong actions) to the same pressure level as the new AR rounds- the difference gets much wider.


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It's a give and take.
With AR-15's if you have two brain cells and a vises you can build them yourself without much problems, don't need to drive and wait and pay a gun Smith for barrel changes and all that good news . Order the barrel and the bolt and it's leggo builder time. You can actually adjust them to fit pretty easy and when you a small person like me at 5'1" fit is really important. You don't need a lathe , milling machines and all this other stuff. No to mention I can do the whole one lower multiple uppers deal. Heck even further I can only have a few BCG's .
No to mention most of these AR based wild cats work off of brass you can pretty easily and affordably get that ranges from range pick up all the way premium Lapua or Peterson.

All of that and I have to give up some pretty wood and a small disadvantage which let's be honest here 80% of shooters really don't need a top high throttle performance out of most. You you don't like AR's and already have the legacy cartridges these are performing similar too then it's just kinda a non starter for you to even bee looking at these as much past a novelty. If your a 100% "a gun is a tool I only have guns that fill a purpose" type of person then yeah these are again non starters. Now if you like me however who has the whole "need" bases covered 15 ways to Friday and jus tlile playing around with stuff but don't wan to go full out $1500-$4000 custom bolt guns made off of legacy cartridge deal....welp these are a extremely viable option

[MostlyLeverGuns]

Brunettes, blondes and redheads, bosoms, butts, long legs, we all have our preferences. Since I was 12(1961) I thought the Model 70 handled like a 2x6 with a pipe stuck to it while a featherweight Savage 99 handles wonderfully. I do have a couple AR-15s, even a Side-bolt 6.5 Grendel, we practice with them every couple months as our 'zombie' guns, same with the plastic pistols in 9mm, light and lots of bullets for carry, but a 1911 or a single action 45 Colt are just more fun. In tough conditions the stainless and polymer stuff does fare better, still hunt with those walnut and blued 99's. But that's just me, I don't judge you, some might think I must be be dumb, OH WELL.

[rockrat]

Almost sounds like close to a 7mm BR.

[Larry Gibson]

Wolfdog91

We see the "almost as good as" play on words all the time when comparing a smaller cartridge to a larger case of the same caliber. The fact is, the smaller case will never equal the velocity of the larger case with a given bullet when both are loaded to the same pressure in barrels with the same effective barrel length [the length of the bore minus the chamber length]. Case capacity, all other things being equal, matters....that's a fact.

As to your selected load data, that particular Hornady manual is holding the psi level down at the SAAMI MAP of 46,000 CUP or less. I suspect the 7mm in the AR was pushing 50,000+ CUP or 60,000 psi +/-. Here is the data from an older Hornady manual showing loads in a 22" Ruger M77 which had an effective barrel length of 19.5". The AR in the video had a 24" barrel with a probable 22.25" +/- effective barrel length. The Hornady data below was developed to a CUP level of 50,000. Note the velocities of 3000 and 3100 fps+. I have duplicated several of those loads and pressure tested them in my 22" barreled M95. The psi measured was in the 57,000 psi range, the European CIP Pmax for the 7x57, and the velocities were commensurate with the listed data.



Now, ponder what the actual velocity would be if we ran the psi up to 60,000 for use in a modern action and put a 24.5" barrel on it giving the same effective barrel length as the AR 7mm had. We'd be pushing that 120 gr bullet up into the 3200 - 3300 fps range. The 7x57 case has the capacity to do the with the 120 gr bullet, the 7mm Valkyrie does not. Then let's consider what happens if a heavier bullet is used in either. The case capacity of the Valkyrie is eaten up very quickly, not so much in the 7x57.

Case capacity matters. With all else comparatively the same the 22 H will never equal the 221 Rem, the 7.62x39 the 30-30, the 300 Savage the 308W, the 308W the 30-06, the 30-06 the 300 H&H or the 300 H&H the 300 Win Mag. There are hundreds of other examles for each caliber. Fact is, the 7mm Valkyrie will never "equal" or "be the same as" the 7x57 unless, perhaps, there is some 120 gr 7x57 ammo loaded out there to SAAMI specs or less(?). When hand loaded or with heavier bullets the Valkyrie just won't cut it in comparison.

It's interesting though and guys can play with it all they want and see nothing wrong with it as I also play with a lot of cartridges just for fun. However, there is no need to unjustly compare a new cartridge a fine old cartridge to justify it. The 7mm Valkyrie fits in an AR15 and the 7x57 does not. If one wants a 7mm AR15 it appears the Valkyrie is a good choice.

[Harter66]

I used a 6.8 SPC and got a 27-130 to almost 2500 fps MV ........ The primer vaporized , but , I almost got 2500 fps with the 141 gr paper patch.....

The 2.26 OAL limit in the magazine means you have to go wider to get capacity. With a 284 case pushed back to 1.8 or so it'd be close but the bolt dogs and barrel extension get pretty thin. At 2.10 the 284 case is all but a dead heat with the standard 280 Rem so shortened 3/10s would be right there with the Mauser .

[Loudenboomer]

I built up a 7mm-08 Ar-10 on a DPMS receiver, 1-8 twist 22" X-Caliber barrel with rifle +2" gas system and Superlative Arms adjustable gas block. StaBall 6.5 powder is a bit on the slow side but has been working well. I set the rifle up to shoot the JLK VLD 180 match bullet. I have many thousands of these bullets and was the idea behind the project albeit little on the heavy side for 7mm-08. Not an Ar-15 but it provides many of the big bullet attributes of the 7mm Mauser.

[35 Rem]

I can't take an AR or any semi auto seriously for anything but self-defense. Reason being that I don't want to either lose all my brass or spend tons of time poking around in the grass looking for it. I'm all for the existence of AR's or other rifles based on military guns for self defense but my take on that is to buy 2 or 3 of them, set aside say 10,000 rounds of ammo for it and then go to a true sporting rifle for most shooting or hunting. Losing brass is too big a negative for a reloader in my opinion.

One thing I think that drives the enthusiasm for AR's among younger shooters is that they have been raised with computers in their hands since day one. In the computer world 3 years old means obsolete and they tend to bring that same thinking along when they get into guns. If it's old, it HAS to be obsolete, and I can EASILY come up with something that will outperform it they think. Tain't so but the still think it.

[trebor44]

WOW! Marketing hype will suck in anyone who left their brain in 8th grade! Note: this is the reading level for the WSJ daily paper.

[Wolfdog91]

I can't take an AR or any semi auto seriously for anything but self-defense. Reason being that I don't want to either lose all my brass or spend tons of time poking around in the grass looking for it. I'm all for the existence of AR's or other rifles based on military guns for self defense but my take on that is to buy 2 or 3 of them, set aside say 10,000 rounds of ammo for it and then go to a true sporting rifle for most shooting or hunting. Losing brass is too big a negative for a reloader in my opinion.

One thing I think that drives the enthusiasm for AR's among younger shooters is that they have been raised with computers in their hands since day one. In the computer world 3 years old means obsolete and they tend to bring that same thinking along when they get into guns. If it's old, it HAS to be obsolete, and I can EASILY come up with something that will outperform it they think. Tain't so but the still think it.

As a 26 yr reloader and shooter ....all I can say is.....ARE YOU SERIOUS LOL . Sweet Lord have mercy

[M-Tecs]

I can't take an AR or any semi auto seriously for anything but self-defense. Reason being that I don't want to either lose all my brass or spend tons of time poking around in the grass looking for it. I'm all for the existence of AR's or other rifles based on military guns for self defense but my take on that is to buy 2 or 3 of them, set aside say 10,000 rounds of ammo for it and then go to a true sporting rifle for most shooting or hunting. Losing brass is too big a negative for a reloader in my opinion.

One thing I think that drives the enthusiasm for AR's among younger shooters is that they have been raised with computers in their hands since day one. In the computer world 3 years old means obsolete and they tend to bring that same thinking along when they get into guns. If it's old, it HAS to be obsolete, and I can EASILY come up with something that will outperform it they think. Tain't so but the still think it.

These work very well as a brass catcher.
https://brassgoat.com/

These are the best but pricy. I love mine. When shooting prairie dogs, I load 7 20 round mags and shoot till it's time to load mags and empty the 140 rounds of brass in the catcher. The time spent loading also allows for the barrel to cool some. I have one spot that normally is an 800 round plus day with 75% kill percentage.
https://www.tacticalbrassrecovery.co...r15-ar10-scar/

Mine is an older version. I got it when they first came out. Mine has caught maybe 100K piece of brass. I normally shoot between 5K and 6K a year out of the AR. Only time brass hits the ground is when I foget to close the zipper on the bottom.

[WILCO]

I have a soft spot for the 7mm Mauser.