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Page AR-15 » AR Variants
AR Sponsor: bravocompany
Posted: 9/13/2016 2:39:22 PM EDT
I'm getting the itch to start a new build and am seriously considering an AR10 platform built around Aero Precision receivers.

I would like to get some thoughts on 7mm-08.

I am aware of the benefits of the 6.5s.  I already have a Grendel AR and a Savage 260. I'm also not interested in a 308.  If after my research the 7mm-08 doesn't work out I'll go with one of the 6.5s.

Intended use:  Semi-Auto for 1000 yard steel targets.  This will be a heavy bench gun.

Some of the factors that have me looking at the 7mm-08:
-Good barrel life
-High BC bullets (especially recent designs)
-More energy at target, easier to determine impacts (assuming the velocity is high enough)

Some factors that give me pause:
-Attaining good velocity without hot loads will be a challenge
-Newer bullets with secant ogive may not work well at mag COL

Typically 7mm-08 looses out to the 6.5s (260, 6.5 Creed, 6.5x47L) when talking 1000 yards due to the limited case capacity resulting in velocities that are too slow to really take advantage of the high BC bullets.  If you can get the velocity high enough then the 7mm bullets can edge out the 6.5s in windage.

My thoughts on the ideal bullet weight for this setup would be in the 160-168gr range.

Obviously one way I squeeze out some extra velocity is to go with a longer barrel but there are gas system considerations in the AR platform.  Would a 26in barrel cause issues with the gas system?

I would really love to hear from anyone who has experience with a 7mm-08 AR 10, reloading for it, and what kind of velocities you were getting.
Link Posted: 9/13/2016 3:06:58 PM EDT
[#1]
I own one.
It is a Laser Beam!
Zero it 1 Inch high at 100m Just trust the zero to 300m. Wow what a caliber. 140gr balistic tips are what I load with. I killed two deer last year with it. Effective, gentle on recoil, and easy to predict
Link Posted: 9/13/2016 3:26:52 PM EDT
[#2]
If you use 7CM (wildcat) you can use heavier bullets.
Link Posted: 9/13/2016 3:54:39 PM EDT
[#3]
I'd go Creedmore for long range.
.308 for large game.
Link Posted: 9/13/2016 4:34:43 PM EDT
[#4]
I love the 7-08 cartridge. I have been contemplating building an AR chambered for it, but alas funds are already spoken for. 26" barrel would help you grab every bit of velocity and shouldn't have much issue with the gas system given appropriate gas port size. What brand of barrel are you looking at?
Link Posted: 9/13/2016 6:26:30 PM EDT
[#5]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
I love the 7-08 cartridge. I have been contemplating building an AR chambered for it, but alas funds are already spoken for. 26" barrel would help you grab every bit of velocity and shouldn't have much issue with the gas system given appropriate gas port size. What brand of barrel are you looking at?
View Quote


It's way early in this idea so I have not looked too closely at barrel manufactures just yet.  Thinking about Krieger but its early.  Probably wont place an order for the barrel until next year.
Link Posted: 9/13/2016 7:59:50 PM EDT
[#6]
Remington used to have the R25 in 7-08.  It won't have a muzzle device on on it but the rifles tend to be great shooters.  IDK if the new gen2 model comes in the cartridge or not.  I have a R25 in .308WIN and it is a fantastic shooting rifle.  Like AR10 type rifles it is heavy.
Link Posted: 9/13/2016 8:56:10 PM EDT
[#7]
Patton, if you already have a Savage 260 bolt rifle, why not an AR10 in the same caliber since you reload?

Honestly every caliber you listed there is pretty darned good within its performance envelope.  The 260 is a hair better than the 6.5C.

7mm-08 is a good round, but 260 sounds better for your really long distance effort.

Hopefully LRRP will respond to this with more knowledge on the 260.
Link Posted: 9/13/2016 10:17:23 PM EDT
[#8]
Link Posted: 9/13/2016 11:34:46 PM EDT
[#9]
The big advantage to 7mm-08 is a lot of factory hunting ammunition on shelves and online, if that's important to you.

I was one of the few on the shelves after SH.

I haven't ever seen a factory target load for it, but it sounds like you will hand load it anyway if you go that route.

For 1000yd, the 6.5mm are hard to beat in drop and drift, unless you go to a 6mm, but then registers are hard to hear or see.

6.5mm 140gr on steel at 1000yds is pretty loud.
Link Posted: 9/13/2016 11:45:45 PM EDT
[#10]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
Patton, if you already have a Savage 260 bolt rifle, why not an AR10 in the same caliber since you reload?

Honestly every caliber you listed there is pretty darned good within its performance envelope.  The 260 is a hair better than the 6.5C.

7mm-08 is a good round, but 260 sounds better for your really long distance effort.

Hopefully LRRP will respond to this with more knowledge on the 260.
View Quote


I reload for a dozen calibers already.  It's part of the hobby.  Commonality and/or practicability are not one of my requirements.  I know the 260 well.  My Savage with a 30 inch barrel is pushing 140 eldm's @2930 fps.  My drop is around 25 moa and a 10mph crosswind is under 6 moa.  I would never be able to get that kind of velocity out of a gas gun in 260, nor would I try.  I do have future plans for a custom, purpose built F-class setup that will probably be in 284 Win, but that's a different rifle with a different purpose and it's further down the line.

So, with that said there are a couple of reasons I am looking at the 7mm-08 vs one of the 6.5s (260, 6.5x47, 6.5 CM).

1) If I compare a hornady 140 eldm @ 2800 vs a 162 eldm @ 2700 I am getting near identical drop and wind out to 1000 yards.  The 7mm will have better barrel life and hit the steel targets with a little more force.
2) It's something different.  Don't see a lot of AR 10s out there in 7mm.   It's a bit of an unknown in this config which adds to the fun.

I really would prefer to keep this thread focused on the 7mm-08 (7mm wildcats like the 7CM are fine) and not turn it into another comparison thread.  Like I mentioned in the OP, after evaluating everything I may end up going with a 6.5 anyway.   That's why I am very interested in hearing from folks who have one of these and reloaded for it.  Good velocity numbers are hard to come by for this combination.  

Really it comes down to this, if I can run a long barrel (24-26in) without running into gas/cycling issues and I can push a 160-168 class bullet to ~2700 fps and get acceptable precision (.5 moa) with the 7mm-08 then I'm building one :)


Link Posted: 9/13/2016 11:49:45 PM EDT
[#11]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
The big advantage to 7mm-08 is a lot of factory hunting ammunition on shelves and online, if that's important to you.

I was one of the few on the shelves after SH.

I haven't ever seen a factory target load for it, but it sounds like you will hand load it anyway if you go that route.

For 1000yd, the 6.5mm are hard to beat in drop and drift, unless you go to a 6mm, but then registers are hard to hear or see.

6.5mm 140gr on steel at 1000yds is pretty loud.
View Quote


Every time I start thinking about a magnum I end up running the numbers against my 260, then think about all that powder and decide to pass, lol.

I can only hear the impacts at 1000 yards if the atmospherics are right. At 750 I almost always here.  Honestly I'm don't think the 7mm-08 would be much different but I do expect the plate to swing more.
Link Posted: 9/14/2016 9:03:09 AM EDT
[#12]
I can't add much to your specific question, but I have a buddy with a factory Remington in 7mm 08.  My buddy reloads for it, but  I don't think he's had a chance to stretch it's legs past 300 or 400 yards.  He likes heavy hitting calibers,  and has a Savage 110BA in 338 Lapua Mag for heavy duty work.
Link Posted: 9/14/2016 10:40:29 AM EDT
[#13]
There was a guy on the Grendel forum who built a 7mm-08 on DPMS receivers I think, started with his own barrel blank.

He started with a long barrel, then cut the barrel down in 1" increments to see what would happen with velocity.

There was a sweet spot for length, but I don't recall what it was.  I'm thinking somewhere around 21"-22" IIRC.

There was an accuracy node with the load he was shooting, I think 162gr AMAX.

He also posted on Snipers' Hide.  FMSniper is his handle.  He's a former SOTIC instructor, good dude.
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