New Colt .308s

[constructor]

We've been using 11 twist 16" barrels for years, sub MOA with 175s. Sometimes the Govt over thinks things.
I wouldn't shoot a 190 or 200gr out of them.

[arptsprt]

Agreed on all points. And the 1 lb weight reduction from the original is nice.

I had an original LE901 and liked it but sold it off for an LMT LM8 MWS. It shot great. In fact, I would say it was softer shooting than the LMT but I still like the LMT better overall.

Another interesting observation is that the Colt website states the 5.56 conversion kit is NOT included and must be purchased separately. This was a complaint the last go around with this rifle until Colt came out with the "2013 configuration" that included the kit. It's not cheap at $200...

Much nicer looking then the original hand guard.

The twist boggles me though. At least do a 1/11".

I won't be trading in my LMT rifles anytime soon, but would love to have a spare 308 in the safe. Using the lower receiver as a dual purpose 5.56 18" SPR would be appealing as well.

[colt933]

Agreed on all points. And the 1 lb weight reduction from the original is nice.

I had an original LE901 and liked it but sold it off for an LMT LM8 MWS. It shot great. In fact, I would say it was softer shooting than the LMT but I still like the LMT better overall.

Another interesting observation is that the Colt website states the 5.56 conversion kit is NOT included and must be purchased separately. This was a complaint the last go around with this rifle until Colt came out with the "2013 configuration" that included the kit. It's not cheap at $200...

I think $200 is cheap. I bought one of the first gen 901s that did not come with the kit and the kit was priced at $295 when it finally became available.

I bought the 901 because I have a RDIAS and this is the only .308 pattern rifle that it will work in. The modular design/conversion from 7.62 length action to 5.56 action is an added bonus. And surprisingly, my 901 is nearly bolt-gun accurate with my M118LR clone load.

I highly recommend switching the stock to a CTR with a limbsaver recoil paid, a MOE+, and also installing the Griffin flash comp. These three easy and cheap modifications have improved an already great rifle and make it much more controllable and pleasant to shoot.

[LRRPF52]

This is right in line with Todd Hodnett's approach to long-range shooting, where he has done a lot of work with bull barreled 16" AR10's pushing the long bearing surface pills with a tight twist, as well as 20" .338 Lapua Magnums. The idea is to maintain spin stability through the transonic speeds, by starting with a much higher spin rate from the muzzle.

I've seen the same thing with my 16" 6.5 Grendel, which has a very tight twist of 1/7.5". I was out shooting in the Western Utah Desert, where we have beautiful opportunities for long range shooting, and some guys challenged me to hit a target at 1200yds that they weren't even near with their impacts from .30-338's, .308's, and some other magnums, since they didn't have any grasp on compensating accurately for trajectory.

I had all the atmospherics already plugged into my program, but never considered shooting past 700yds with a little 1.5" long case with such little capacity, especially from a 16" barrel. My program told me I needed 14.4 Mils, so I dialed it in, got set up, and broke the first shot.

I was genuinely surprised when it impacted barely off the left edge of the target, and I placed the next 4 rounds on target as fast as I could index the reticle and ice-sickle the trigger, spotting my own hits. This was with a factory 123gr A-MAX load at 2450fps, which isn't even that fast, but the BC does the work.

I've had similar results with 175gr SMK from the .308 out to 1118yds near the same area, in a little colder conditions. Wind was basically dead in both circumstances.

If I were playing around with this, I would see what I could do to optimize the rate of twist for my initial start pressure, then go progressive with a Bartlein barrel, after a theoretical analysis and hypothesis based on modeling. Start pressure considerations with a tight twist and long bearing shank would need to be balanced with optimum spin stability for exit near the muzzle. A RLGS 16" seems to make the most sense for the .308 in this regard, so we don't hit the gas port so hard with the elongated pressure curve typical of slow-burning powders necessary for the long shank pills, like a 175gr SMK.

I suspect a 1/9 could go progressive down to 1/7 near the muzzle. 5R rifling would probably be best to limit shearing forces on the jacket as it goes through a progressively tighter ROT.

[scottryan]

The 18" with short handgaurd is lame.

[TheBelly]

FBI testing has concluded that nothing slower than 1:10 adequately stabilizes the newer generation of duty ammo at 16" velocities. They are getting longer, and the shorter barrel is making them slower, necessitating in increased twist. Don't be surprised when 1:7 7.62 is available.

Another issue is use with a suppressor. While 175s tend to be ok from 1:11 down to 16", there is an increased risk of baffle strike, exacerbated in certain conditions, and even more so with more contemporary projectile design.

There is no shortage of good groups with ammo and twist rates that are sub-optimal, but those exceptions do not disprove the data that has been collected over the last 25 years.

What are specific examples of 'newer generation of duty ammo'? What are the velocities for this projectile from a 16" barrel?

[LRRPF52]

Just broke down a Colt 901 to measure the Bolt Carrier length.

SR-25 BC: 7 7/8"
AR15 BC: 6 11/16"
Colt 901 BC: 7 1/4"

The bolt appears to be a standard SR-25 pattern bolt inside of a shortened carrier.

I also noticed that they relieved the forward, bottom, outer edges of the bolt carrier that normally form channels for the cartridges as they sit in presentation from the feed lips. They are much more relieved than even the special 7.62x39 carriers that have to be used on the MGI Hydra when combined with the AK mag well for AK magazine function in the AR-15.

There is a lot of open architecture for the Colt 901 to grow in ways that I think indicate some foresight on their part. It's a very interesting design, that seems to draw back to the original AR10's from the late 1950's, while combining modularity and monolithic upper receiver developments from the last decade.