25 Grendel or 25 BR

[LRRPF52]

Just got in some Blackjack 131gr .257 ACE samples to start playing with.

I've always wanted a quarter bore since my Grandpa loved .257 Roberts, but I want it in an AR15 of course.

I've been looking at 6mm AR, but think this might have a chance to beat it.




.330 G7 1000yd verified BC, really meant for 25x47 Lapua and 25 CM.

Longer than any 140gr class VLD/SMK/Scenar bullet I have in 6.5mm.

Wouldn't suffer from anemic plate impacts of the 6mm at distance, or the recoil of 140gr 6.5mm, but brings BC superior to most 140gr 6.5mm and definitely smokes 6mm BCs, even the DTAC.

I'm doing some mocking up right now.

[BCHunter]

What do you expect for coal? And how much case capacity do you anticipate with it?

[biodsl]

Subscribed.

[LRRPF52]

What do you expect for coal? And how much case capacity do you anticipate with it?

To load this in a Grendel case and have the projectile shank/boat tail meet the case neck/shoulder, it will need 2.370" COL minimum.

In a BR, it looks like we can get it shorter since the neck/shoulder on the BR is 1.238", and the BR has way more neck support/long neck for feeding stability of the concentricity.

I don't want to suffer from the problems that I think are happening with the .224 Valkryie in gas guns.

Also looking at 25 WSSM, which would duplicate or exceed 25x47 potentially.

I need some BR brass with dies to expand and what not.

The only bullets I'm finding with a higher BC than this 131gr ACE in the 6.5mm realm are:

* 147gr ELD-M at .351 G7
* 150gr SMK .713 G1/.360-ish G7

I don't like pushing past 130gr, so this ACE is on the edge, but has insane BC for weight. Seems like a beautiful little bullet for the AR15 that will retain energy extremely well, while suffering from very minimal wind deflection. We need more COL though I think.

[Huckleberry75]

Miles and Logan know how to create beautiful bullets. Those Aces are ..well, Aces!

[Sticks]

This outta be good.

[sneaky one]

I think I'll sit down with BFT- I have an idea for a midsized AR- to handle the 6.5-47 Lapua, a new .257 cal. round, the one that L 52 is thinking of.
And a few that are just longer than the Grrr.

The .257 is already loaded from Sharps, co. for AR's. should be an easy dimensions swap on the computer. This could get interesting.

Think-- AR 12, or 12.5

Just talked to BFT, we'll start on it this week. I'm stoked!

[grayfox]

That Sharps "25-45" AR is a necked up 223 case...
I like the idea of starting with the grendel case. Less anemic-ness.

[SightedIn]

Just to confirm, when you say 25 BR are we talking a 6mmBR necked to 25cal?

[LRRPF52]

Just to confirm, when you say 25 BR are we talking a 6mmBR necked to 25cal?

Yes. I really think that case will be ideal for low recoil and sufficient mv to get this bullet going.

With the 25x47 Lapua and 257 Creedmoor, they're already smoking 6.5 CM performance, as well as 6 Creedmoor, and a 131gr will actually move the plates so ROs can see it.

The 6s don't have much retained energy to swing plates or make a big splash on steel once you get out there.

I love the 6mm for the areas it shines, which are varmint, TGT, cutting paper at distance, low recoil, super flat trajectory.

The .257 ACE 131gr gives you the best of both worlds between 6.5mm retained energy, but super flat trajectory and lower recoil of the 6mm when shot from -08 cases.

-08 cases are a non-starter in the AR15 frame, so I think the 257 BR combination would feel like shooting a Grendel, but doable from a smaller rifle chassis and mags.

For optimum projectile/brass arrangement, it's going to require a COL that no AR15 magazine or receiver set can handle currently.

For loading long in Grendel, it won't require much at all to get neck tension. Bushing dies will work.

Mocking it up in Grendel, it already has some neck tension in Lapua factory virgin brass.

[SightedIn]

Ok yeah that sounds pretty awesome. My only question is that isnt a 6br bolt face a .473? Can that fit in an ar15( as opposed to a ar10)?
Actually scratch that i just remembered the 30AR fit in an ar15.
What bolt would you use? Some sort of .473 face but ar15 bcg carrier hybrid?
Got my interest totally piqued here

[grayfox]

For optimum projectile/brass arrangement, it's going to require a COL that no AR15 magazine or receiver set can handle currently.

For loading long in Grendel, it won't require much at all to get neck tension. Bushing dies will work.

Mocking it up in Grendel, it already has some neck tension in Lapua factory virgin brass.

So are we talking use of a windowed mag? or will this have to be single loaded?
Or re-barrel a howa mini and use its mag length?

[go4shoot]

I'm hoping for a lot of bullet manufacturers are going to jump on the 25 caliber and produce some new high bc bullets.

[bj139]

Ok yeah that sounds pretty awesome. My only question is that isnt a 6br bolt face a .473? Can that fit in an ar15( as opposed to a ar10)?
Actually scratch that i just remembered the 30AR fit in an ar15.
What bolt would you use? Some sort of .473 face but ar15 bcg carrier hybrid?
Got my interest totally piqued here

458 SOCOM bolt should work. Same case head size as 30-06.

[SightedIn]

458 SOCOM bolt should work. Same case head size as 30-06.

Sounds like a plan lets build this thing! Well LRR would actually be doing the building😎

[LRRPF52]

Ok yeah that sounds pretty awesome. My only question is that isnt a 6br bolt face a .473? Can that fit in an ar15( as opposed to a ar10)?
Actually scratch that i just remembered the 30AR fit in an ar15.
What bolt would you use? Some sort of .473 face but ar15 bcg carrier hybrid?
Got my interest totally piqued here

The BR case is a .473" head like a .308 Win., .30-06 Springfield, etc. Several people have already been doing wildcats with the BR in the AR15, but there has never been a receiver really made for it, let alone mags.

We're at the stage in AR15 development, I feel, where it's time to really nail down another industry-supported option in the receiver sizes and magazines, without compromising the familiarity of the AR15 form factor, but no longer being constrained to the limitations of the 5.56 magazine, magazine well, and other core components of the 5.56 NATO pressure containment system and its diminutive size.

The overall form factor, weight, handling, and center of balance need not suffer in order to step into new high performance intermediate cartridges, and the size/weight/recoil of the AR10 can be avoided while matching or exceeding the performance of the 6.5CM when looking at hit probability, wind deflection, and sight picture disturbance.

Just to give one an idea about the numbers the 131gr .257"/6.35mm projectile allows.

Assuming 131gr ACE at 2500fps mv from a Grendel case:
600yds 1779fps 921ft-lbs 4.5 mils drop 1.1 mils drift
1000yds 1369fps 545ft-lbs 10.3 mils drop 2.1 mils drift
1300yds 1109fps

Assuming 131gr ACE at 2700fps with a BR/Dasher case
600yds 1947fps 1103ft-lbs 3.7 mils drop 1 mil drift
1000yds 1517fps 669ft-lbs 8.5 mils drop 1.8 mils drift
1450yds 1109fps

6.5 Creedmoor 140gr ELD-M 2710fps .305 G7 BC
600 1899fps 1121ft-lbs 3.8 mils drop 1.1 mils drift
1000yds 1442fps 646ft-lbs 8.8 mils drop 2 mils drift
1350 1107fps

25 Creedmoor/.257x47 Lapua 2900fps 131gr ACE
600 2116fps 1302ft-lbs 3.1 mils drop .9 mils drift
1000yds 1665fps 806ft-lbs 7.2 mils drop 1.6 drift
1600yds 1106fps

The main reason competitors have drifted away from 6.5CM and .260 Rem in PRS is recoil and muzzle blast/climb-induced sight picture disturbance, which prevents an individual shooter from seeing what happens on-target/near target in the scope, followed by 2-3 day match fatigue. This translates to other shooting disciplines and hunting.

6mm has been the go-to bore for PRS for a while now, with 6 Creedmoor and Dasher being pretty popular, as well as 6x47 Lapua. They can push speed to make up for lower BCs compared to the 6.5mm, get a very flat trajectory and minimal wind drift, and track the sight picture throughout the shot. Problem is retained energy on target and being able to swing the plates for ROs to be able to give you credit.

As you can see with the .257" 131gr ACE, it has more energy at 1000yds than a 10mm does at the muzzle, and that's true with several 10mm loads even compared to the .257 Grendel case with this bullet.

No matter how you slice it, this type of quarterbore projectile really steps things up a notch for wildcats and new factory ammo options.

[LRRPF52]

Looks like 2.430" COL will work with the 131gr ACE in a Grendel case run through a bushing die.

[grayfox]

Simplest way I can think of is to find someone who can 'cnc an upper/lower set, call it a "stretch-15", add maybe 0.2-0.25" to overall length via longer magwell up through the lower/upper/carrier and CH, lengthen the buffer by the same to allow the bcg to cycle. Maybe even widen the lower what, 0.2" again to allow for polymer mags... or keep it same width and use a single-stack or a "1.5 stack".

All things considered you should be able to leave the metal/finishing/material qualities the same -- seems like this would be an incremental upgrade that seems possible.

[Kilco]

I've had such amazing luck with the 6 grendel, you have sparked my interest with this.

Velocity is where I'm a skeptic. Not a doubter, just a skeptic.

I've got to look at my data, but I believe I'm pushing the 110 SMK 2640 from a 22" barrel, and it's a warmish load.

[bj139]

I just remembered this.
https://www.maddogweapons.com/65-timberwolf.html