So, I found that one of the reamer rental places has reamers and gauges for the 24 Nosler. And I've got a lathe but am not a machinist by any stretch of the word. And I once watched a gunsmith chuck up one of my barrels once in a 4-jaw chuck and true it up. And I watched a video on YouTube showing how to chamber a barrel. And I'm just this kind of guy. So, I ordered a Shilen barrel blank, some AR-15 extensions, some tools, some brass, a set of dies, a range rod for .243 bores, and some other stuff and I'm going to attempt to chamber a barrel in 24 Nosler. All the stuff should be here by middle to end of next week. Once I monkey around with getting it to run true in the lathe I'll "order" the rental reamer and give it a go.
I'll let y'all know how it goes, sink or swim. Hopefully it'll work out and I'll end up with a functioning barrel and platform to test with.
But, with the reduced powder capacity and rebated rim design, I suspect that Constructor's comments about it dying like the 22 Nosler are accurate. With no parent case to size from, 24 Nosler brass, like Terminators, only comes from one place (Nosler) and it's not what I'd call "cheap" and there were a number of "out of stock" statuses where I looked. And if the 6mm Predator/.243 LBC/6mm Grendel/6mmAR cartridges fire the same projectiles at higher muzzle velocity and the brass can be readily formed from 6.5 Grendel cases then the 24 Nosler, with no serious industry support, seems destined for "also-ran" status.
--HC
So, about 6 weeks later and I'm back. I got it done. I learned a lot.
First, about the 24 Nosler: at first glance it seems similar to the 6x45 (a.k.a. 6mm-223). Major differences would be: 1) 24 Nosler needs 24 Nosler brass (it has no "parent case") whereas the 6x45 uses regular 223 Rem brass very simply necked up to a 0.243 neck (dies readily available for both), 2) 24 Nosler is a shorter, wider case which would seem to accommodate the heavier bullets (whereas the 6x45 uses standard 223 Rem brass and, being longer, was kind of pushing it with the 70gr Nosler BT I tried), 3) 24 Nosler cartridges do not seem to feed well from 6.5 Grendel mags (that's what I had with me that day) at least the ones made by E-Lander (probably would have worked well from the PRI 6.8 mags I have but I didn't test them because they weren't with me that day) whereas the 6x45 feeds from standard 223 Rem magazines just fine. The 6x45, which seems to be the closest "competitor" to the 24 Nosler is super sexy because it's nothing but a barrel swap (mags, bolt, headspace gauges, etc. all work...I've made a barrel in that, too, now). This post isn't to compare the 24 Nosler to other 6mm variations for the AR-15, though, so that's enough of that (I lie like a cheap rug).
I bought a cheap 6mm barrel blank from Numrich, rented a reamer from 4D (overall a good experience but, after several rentals now from them, they do not respond to phone calls which is a pill when you have a problem), bought a 0.243 range rod and 0.243 pilot bushings, and figured the rest out. I then chambered a barrel for a Savage model 12 FV in 6.5 BPC...wow, that's a lot easier than the AR barrel. Anyway...the barrel blank I got was 25 inches long so I just chambered one end, cut a profile of about 0.980" from the barrel extension end to a rifle-length gas block journal, short drilled the gas port (I didn't go all the way in case I decided to change gas-system length), and finished the barrel at full length just under 0.750" diameter. I loaded a bunch of cartridges right in the middle of the load data for the powder I chose (Benchmark) and all with the same bullets and seating depth. I then fired 3 rounds at each length as I cut the barrel down from 25" to 16", and recorded the data from my chronograph. I thought that might be of interest to the forum. I did NOT shoot any groups. I did not shoot groups because there are too many variables to account for in order for the results to have any value to the community.
This is what I loaded and shot, this is not a recommendation of a load: Use only data from reputable sources (like Nosler), just like I did.
24 Nosler
CCI #41
Benchmark 26.0gr
2.210" COL
25": 3,051 FPS avg (only 2 shots recorded...I hate my Caldwell chrono)
24": 3,046 FPS
23": 2,967 FPS
22": 2,937 FPS
21": 2,909 FPS
20": 2,859 FPS
19": 2,853 FPS
18": 2,820 FPS
17": 2,799 FPS
16": 2,762 FPS
I chose not to go any shorter than 16" because 1) I wanted the freedom to use it any time with any of my lowers (I only have one SBR lower), and 2) the velocity was getting low enough that the barrel wouldn't be useful for my purposes if I kept bleeding FPS. While I only tested one powder/bullet combination, this information should be useful as a general guideline for what to expect from this cartridge (24 Nosler) in different barrel lengths. Of course I was wearing hearing protection, but I could tell an appreciable difference in muzzle report, particularly in the shorter lengths. I have no way to quantify the difference, though.
For comparison, I loaded up 3 cartridges for the 6x45 which I tested the same day. I started off with a POS barrel from True Sporting Arms which was clearly a manufacturing defect sold as a barrel with only a chamber and extension threads cut (no profile, no gas port, no barrel extension). With that POS in-hand, I started practicing how to finish an AR-15 barrel and I drilled the gas port in the wrong location (you mean you can't trust information found on the Internet? NO! Get out of here!). After successfully finishing the 24 Nosler barrel (and getting accurate location information for gas ports), I decided to cut the chamber off the POS barrel and make it a 6x45. I then cut the barrel to length behind the mis-drilled gas port, leaving it at a finished length of about 11-something inches and put a gas port in it at carbine length. The three cartridges were loaded with the same powder and amount and had the same bullets as the 24 Nosler rounds tested. The major difference, besides length, was that the POS barrel seems to have 3 groove polygonal rifling whereas the Numrich blank has 6 groove "standard" rifling (some insist that the 3 groove polygonal rifling allows faster velocity due to reduced barrel friction). I shot one round into the dirt with the rifle held on the other side of a 1/2" thick sheet of steel (it had a gun-show special BCG and upper, both new, which cost me combined $150...not a lot of trust there). Once it shot a round and didn't blow up, I shot the next two rounds over the chrono and got an average of 2,515 FPS. Not bad for an 11 inch or so barrel. I mention that for velocity comparison of the charge/bullet combo...but they were different barrels/construction. FWIW.
There are too many 6mm wildcats for the AR-15 platform and some of them are the #$%# same, just named differently, so it is not possible to easily compare them. The 24 Nosler gets props for having SAAMI specs and bona fide load data from Nosler and having new brass (no forming required) available. If it didn't have that darned rebated rim, I'd be excited about it. For comparison, there is bona fide 6x45 load data from some sources (Hodgdon for one) and brass is readily available and easily "formed" ("formed" is a joke...just resize .223 Rem brass like you normally would but with a 6x45 die: it's so fast and easy that I didn't think anything had changed until I found that I could now seat a 6mm bullet in a .223 Rem case). Dies are available from Redding (I think both of mine are Redding) for either one. Maybe the 24 Nosler would be better for heavier bullets because there's more magazine length available for the bullet because the case is wider. Since neither seems to be available "off the shelf" from any supplier (barrels), you're kind of hosed on laying hands on either one of them in a timely fashion. The most readily-available 6mm variant for the AR-15 platform I found was AR Performance and their 6mm Predator. I had to call the guy to find out that they had them in-stock (the site said out of stock) but he was super nice to deal with and the barrel and dies showed up the same week and the thing shoots great and didn't cost a fortune. But then you have to have a 7.62x39 bolt (got one from Maxim), and you're into using Grendel brass...and E-Lander mags....and we're in the rabbit hole of 6mm wildcat variants for the AR-15.
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I hope this helps some of you folks, it sure helped me. I had a great time learning how to chamber barrels...I'm making all kinds of stuff now...it's kind of hard to quit.
--HC
