02-19-2015, 05:04 AM
The Grendel SAAMI chamber has been described as a machine gun chamber that will shoot with exceptional accuracy.
Sure, you can get every projectile to shoot well from any of the chambers with the right seating depth, but magazine feeding then become another affair, and a single load one when you have insane amounts of jump.
Benefits of the SAAMI chamber are numerous. The difficult part of it is on the manufacturing end, where a barrel smith or rifle builder really needs to pay close attention to what is going on with reamer life, but that should be the case with any reamer.
Any of the variant chambers will suffer from running the reamer ragged like any other chamber design, once you go below what will work with a SAAMI maximum cartridge.
We're seeing this throughout the industry in .308, .223, 5.56 NATO, you name it. If you have lazy people in charge of tooling and reaming, expect a lot of returns.
One of the main reasons we have variant chambers is because rifle builders didn't want to deal with licensing for Grendel reamers before the Grendel was a SAAMI certified cartridge, and the demand was such that rifle builders needed to respond to customer wants, so Les Baer did the .264 LBC-AR. You also had the Arne Brennan CSS chamber, which has a .295" neck versus .300".
In my own experience, as well as many others here, the SAAMI chamber just shoots no matter what bullet I load in it, from reasonable magazine COL's for the AR15, namely the 2.200-2.275" region. You don't want to start pushing much further than that since the AR15 magazine well itself is 2.395" without a magazine, and you need material to comprise the body of the magazine of course.
Production variances in magazines can't be held to extreme tolerances and be sold for under $20, so it makes zero sense to throat an AR15 for COL's much over 2.260" for factory ammo, and that's even pushing it when you look at 5.56 magazines and COL of that cartridge, which are shorter than 6.5 Grendel.
The Grendel is a very good balancing point at the end of the day, when looking at the constraints of the AR15 dimensions, while providing exceptional accuracy. Sure, you can throat a chamber so that you can load way out, but now we have a single-shot fed from a lead sled, which doesn't make a lot of sense if using the AR15 action.
The idea that a reamer should just be made with a longer throat so it lasts longer for production ignores things like the neck diameter, mouth location, side walls, etc. You have to replace reamers as a rifle builder, no matter what reamer you use. It doesn't make sense to cut corners in the mindset that you will get a few more barrels out of a reamer, when reamers cost $145, and that cost is distributed across ~200 barrels. You're talking about 72.5 cents per barrel.
As a customer, I'll spend that whopping 72.5 cents, plus inspection costs/skilled labor for a chamber done correctly, whether it's a .308 Winchester or a .223 Wylde. I don't want someone touching my barrel if their mind is nickel and diming the process to death like that.
The other thing is that if there is a chamber design for this cartridge, it was tested.
There is nothing inherently wrong with the .264 LBC-AR chamber, but it does have a tighter neck. There are pros and cons to a tighter neck. Most people who have the .264 LBC-AR chamber seem to be happy. The steel case might pose problems for some of the tight-necked chambers, since it has a coating and wider tolerances.
Sure, you can get every projectile to shoot well from any of the chambers with the right seating depth, but magazine feeding then become another affair, and a single load one when you have insane amounts of jump.
Benefits of the SAAMI chamber are numerous. The difficult part of it is on the manufacturing end, where a barrel smith or rifle builder really needs to pay close attention to what is going on with reamer life, but that should be the case with any reamer.
Any of the variant chambers will suffer from running the reamer ragged like any other chamber design, once you go below what will work with a SAAMI maximum cartridge.
We're seeing this throughout the industry in .308, .223, 5.56 NATO, you name it. If you have lazy people in charge of tooling and reaming, expect a lot of returns.
One of the main reasons we have variant chambers is because rifle builders didn't want to deal with licensing for Grendel reamers before the Grendel was a SAAMI certified cartridge, and the demand was such that rifle builders needed to respond to customer wants, so Les Baer did the .264 LBC-AR. You also had the Arne Brennan CSS chamber, which has a .295" neck versus .300".
In my own experience, as well as many others here, the SAAMI chamber just shoots no matter what bullet I load in it, from reasonable magazine COL's for the AR15, namely the 2.200-2.275" region. You don't want to start pushing much further than that since the AR15 magazine well itself is 2.395" without a magazine, and you need material to comprise the body of the magazine of course.
Production variances in magazines can't be held to extreme tolerances and be sold for under $20, so it makes zero sense to throat an AR15 for COL's much over 2.260" for factory ammo, and that's even pushing it when you look at 5.56 magazines and COL of that cartridge, which are shorter than 6.5 Grendel.
The Grendel is a very good balancing point at the end of the day, when looking at the constraints of the AR15 dimensions, while providing exceptional accuracy. Sure, you can throat a chamber so that you can load way out, but now we have a single-shot fed from a lead sled, which doesn't make a lot of sense if using the AR15 action.
The idea that a reamer should just be made with a longer throat so it lasts longer for production ignores things like the neck diameter, mouth location, side walls, etc. You have to replace reamers as a rifle builder, no matter what reamer you use. It doesn't make sense to cut corners in the mindset that you will get a few more barrels out of a reamer, when reamers cost $145, and that cost is distributed across ~200 barrels. You're talking about 72.5 cents per barrel.
As a customer, I'll spend that whopping 72.5 cents, plus inspection costs/skilled labor for a chamber done correctly, whether it's a .308 Winchester or a .223 Wylde. I don't want someone touching my barrel if their mind is nickel and diming the process to death like that.
The other thing is that if there is a chamber design for this cartridge, it was tested.
There is nothing inherently wrong with the .264 LBC-AR chamber, but it does have a tighter neck. There are pros and cons to a tighter neck. Most people who have the .264 LBC-AR chamber seem to be happy. The steel case might pose problems for some of the tight-necked chambers, since it has a coating and wider tolerances.
NRA Basic, Pistol, Rifle, Shotgun, RSO
CCW, CQM, DM, Long Range Rifle Instructor
6.5 Grendel Reloading Handbooks & chamber brushes can be found here:
www.AR15buildbox.com
CCW, CQM, DM, Long Range Rifle Instructor
6.5 Grendel Reloading Handbooks & chamber brushes can be found here:
www.AR15buildbox.com