Carbine Barrel Length

[oregonradman]

Is a 16in barrel adequate for the 6.5 Grendel? I'm looking for a patrol type carbine length gun.

[Jamie45]

About three weeks ago I got one of Bill Alexander’s 16” uppers. I wanted a light general purpose “walking around” rifle as a companion piece to my heavy target rifle. It has only made one trip to the range so far (about 50 rounds downrange), but I am getting 1.5” – 2.5” groups with factory ammo at 100 yds – 123 grain from AA & Hornady and AA’s 129 grain loads. It doesn’t like the Black Hills load (3.5” and Wolf MPT shot about 3”. No chrono data yet. I am expecting accuracy to get a bit better as the rifle gets broken in and I will also be working up some hand loads. Overall I am happy with it and “I would recommend this to a friend”.

[oregonradman]

Did you get the AA tactical, ultralight or the GDMR? I'm looking at the GDMR. I was hoping for 1MOA or better...

[RStewart]

I have the 16" Tactical and get 1" moa with Sierra 120 SMK w/2520 reloads.

[oregonradman]

Thank you replying. Do you happen to know bullet drops with that load from out to 400 or 500 yds? Also, have you used Win 748 powder?

[RStewart]

Thank you replying. Do you happen to know bullet drops with that load from out to 400 or 500 yds? Also, have you used Win 748 powder?

I have not used the 748 myself. I tried H335, BLC-(2), Varget and 2520. 2520 gave me the most consistent load. But, that's for my rifle, yours might like a different mixture.
I have dopes out to 600 yards: 2441 fps at muzzle (30.6 grains 2520 loaded to 2.20")
Range Drop FPS
100- 0.00 2314
200- -2.32 2184
300- -5.33 2058
400- -8.69 1937
500- -12.38 1822
600- -16.43 1712

I have an AA 20" Hunter upper I'm working up loads for also.

[rkflorey]

I carried an AR-15 in patrol with the 16" barrel as an LEO for years and felt it was near perfection. You get good ballistics from the barrel length and its not so long as to get in the way. If I could have used my Grendel instead of .223 it would have been perfection. The shorter barrels are great if you are going to do building searches and the like but in IMHO the tax stamp and loss of velocity are not worth the shorter barrels and anything longer than 16" tends to get in the way.

[Jamie45]

Did you get the AA tactical, ultralight or the GDMR? I'm looking at the GDMR. I was hoping for 1MOA or better...

I got the tactical. I would expect the GDMR to give better accuracy with it's Satern cut rifle barrel and other high end goodies. I pretty much accepted going in to this that a lightweight 16 would not deliver the performance of my heavy target rifle.

[oregonradman]

With the somewhat slower velocities of this cartridge, I was worried that I would be giving up too much with a 16in barrel. Looks like that is not true. Thanks for everyone's replies!

[noone]

I have had really good luck with 30.3 grains of W748, 123 grain Scenar, lapua cases, CCI450 primer. Velocity out of a 19.5 inch barrel during summer is around 2450fps. (30.5 is the max load, so work up to it)

[VASCAR2]

I've got a J&T 16" CAR barrel upper I put on a Double Star lower with RRA LPK and I really like this rifle. I to am a LEO and think this makes a great carbine for walking and hunting. Hopefully the weather will break and I can start chronographing some of my loads. I've read the 6.5 Grendel loses about 30 FPS per inch or about 120 FPS less than a 20". Considering I wanted a shorter range carbine like my duty rifle I have been very satisfied with my J&T. My J&T has shot some very good groups at 100 yards and I'm hoping to shoot some longer distance soon.

[bwaites]

Vascar, most people find the Grendel loses 15-20 FPS per inch, which is why for general use anything over 20 inches is not much of a problem. If its only 120 FPS between a 20 and 28", only long range competitors really care much!

[LR1955]

Thank you replying. Do you happen to know bullet drops with that load from out to 400 or 500 yds? Also, have you used Win 748 powder?

OR:

You will most likely find 748 to be pretty slow in the muzzle velocity area.

I have found 2520 to give the highest velocities and most consistent performance with bullets from 100 to 123 grains.

LR55

[usar_ds]

I use a AA 16" grendel, mine is the "tactical model" my average grouping size at 100m is about 1 moa with wolf, smaller with AA ammo.

[Rootshot]

I have a 16" AA Tactical Upper. Accuracy is about 2-3MOA which is acceptable for hunting. I chronographed some loads out of it this Wednesday using an Oehler chronograph.

My hunting load is 28.0g IMR 8208XBR, Lapua Brass, Wolf 223 primers, 120gr Barnes TTSX, OAL 2.285". Out of the 16" barrel, this gets 2425fps. Out of my 22" JP Grendel, it gets 2450fps. For hunting, I see no advantage to carrying a longer barrel if the average V0 delta is only 25fps. If this weren't a 3 screen Oehler, I wouldn't have believed this. This is a compressed load that does loosen primer pockets a bit, so I don't advise you duplicate it.

Surprisingly, I found that there is a greater velocity difference (150-200 fps) between my 16" and 22" barrels with lighter 107gr Sierra Matchking bullets.

--Rootshot

p.s. Going pig hunting next weekend

[usar_ds]

OK, sparks another question to mind..

what distance do you guys use for your back up irons or reflex sights on yer carbines?

originally, for my back up irons I was going with a 50m zero to put me on point for up to 200m, however I noticed that it ended up leaving me shooting 9" low at 300m, so I ended up switching to a 40m zero that puts me a 2" high at 100m 3.5" high at 150m, 2.5" high at 200m, and only 6" low at 300m.

those are least my results
any thoughts?