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1/22/2020 12:12:56 PM
Posted: 7/20/2008 3:52:56 PM EST
Opinions on max effective range for a 7.62x51 or commercial .308 out of a 16.5" bbl with a good, high power optic?

Looking at a POF .308 with a 16.5" bbl....I want a 20" but can't find one and the wait is 5-10 months to have one built.

Just wondering if the 16.5" will be far enough reaching.....600M is about as far as I'd ever shoot.

TIA,
Sean
Link Posted: 7/20/2008 6:00:54 PM EST
You lose some velocity from the 16", but I don't feel that it is enough to worry about the difference. You will have to adjust for windage and elevation a bit more, but I feel it is do-able.
Link Posted: 7/20/2008 6:04:22 PM EST
Quoted from another member on this site...

Here are some 308 velocities with my reloads of 45.6 grains of Varget/155 grain Hornady Amax:

20" Armalite CL barrel: 2700
18" Armalite SS barrel: 2650 (Barrel shortened from 20" & threaded by Adco)
16" Armalite CL barrel: 2600
14.5" Noveske barrel: 2530
12.5" Noveske barrel: 2480
All velocities rounded off to the nearest 10 fps, strings of 10 shots, 15" from chrony, barely above sea level, and temps from 45 to 65 (they were all chronographed on different days). I was really surprised at the 12.5" velocities as I was expecting to get closer to 2400.
Link Posted: 7/20/2008 6:25:43 PM EST
I'm getting 2515fps from 44.5 gr of varget and a 168gr A-max out of a 16" DPMS LR 308 AP4. According to my ballistic calculator, this should still be barely supersonic at 1000yds. I'm heading down to a spot where we shoot out to 1000yds plus in a few weeks, and I'll give it a try with this load and see if I can hit anything
Link Posted: 7/20/2008 6:40:42 PM EST
I don't know how much it will help; but I've got a DSA FAL with an 18" barrel. Last year I visited my nephew (who is in the Army) and--after a bunch of paperwork--we went shooting at the range on base. They had steel silhouettes from 200 to 750 yards at various places. Both he and I had no problems hitting all the way out to 750. (I have a Leupold VX-1 3-9x40 scope on it.) We were shooting South African 7.62x51 NATO.

Personally, I think a 16.5" would work out to 600 based on my experience; but all I have is my personal experience to go by, not any hard data.

Hope it helps.
Link Posted: 7/20/2008 6:45:55 PM EST
2600 fps, 150gr bullet. At 300 yds 5 inch drop, at 500 yds 48 inch drop. I would say not much past 300 yds. Here is a link that may help.

www.biggameinfo.com/balcalc.aspx


Link Posted: 7/21/2008 4:00:40 AM EST
Hmmmm....interesting...mixed bag.

I thought I read you'd lose approximately 40 fps for each 1" of barrel you lose (at least in a 22" bbl'd M1A).

I think I'm more confused than when I asked the question now.

Any more opinions/experience?

Sean
Link Posted: 7/21/2008 5:47:24 AM EST

Originally Posted By Roughneck43:
I would say not much past 300 yds.


Link Posted: 7/21/2008 6:25:23 AM EST
I'm shooting a 16" barreled LR308T. I hand load 125grn. Nosler ballistic tips over 44 grns of Varget and get close to 2600 fps. I don't remember the exact numbers. It's pretty obvious to me that shooting a lighter bullet can compensate a little bit for a shorter barrel length.
Link Posted: 7/21/2008 10:36:27 AM EST
poopile, I have the same model as you and was wondering about the 110-125gr loads. Are you noticing any premature high pressure signs or accuracy problems with the tighter 1:10" twist with the lighter loads?

I would expect that a 110-125gr could be run close to 2900-3000fps out of a barrel the length of the 308T, but was perplexed as to why the tight twist was used as is typical for heavier 168-180gr loads.
Link Posted: 7/21/2008 10:47:43 AM EST

Originally Posted By Roughneck43:
2600 fps, 150gr bullet. At 300 yds 5 inch drop, at 500 yds 48 inch drop. I would say not much past 300 yds. Here is a link that may help.

www.biggameinfo.com/balcalc.aspx




I plugged in 2700 fps....to simulate the 20" bbl....it still drops 44"@ 500. Moving out to 600 yards....20" bbl is 80" and the 16" bbl is 87".

If you go to a 24" bbl (around 3000 fps)....you're going to still drop 63" at 600 yards....according to that calculator. Are you sure it's accurate? With a 24" bbl and 3000 fps, I would think it wouldn't drop that much.

Sean
Link Posted: 7/21/2008 10:54:20 AM EST
The drop calculations are close. The key is to get a scope/base combination with enough elevation to dial it up.
Link Posted: 7/21/2008 3:35:47 PM EST

Originally Posted By asknight:
The drop calculations are close. The key is to get a scope/base combination with enough elevation to dial it up.


Thanks for the confirmation. For the difference of 4" at 500 yards and 7" at 600....I might as well go with the 16.5" bbl over the 20".

Sean
Link Posted: 7/22/2008 4:33:11 AM EST

poopile, I have the same model as you and was wondering about the 110-125gr loads. Are you noticing any premature high pressure signs or accuracy problems with the tighter 1:10" twist with the lighter loads?

I would expect that a 110-125gr could be run close to 2900-3000fps out of a barrel the length of the 308T, but was perplexed as to why the tight twist was used as is typical for heavier 168-180gr loads.


asknight, I haven't noticed any high pressure signs at all. I've ran close to 200 hand loads by now, and have reloaded those cases 2 or 3 times over. As for accuracy, I shot 2 groups of 3 at 100 yrds right after break-in, and they both had 2 holes touching with the 3rd opening it up to about 3/4" of an inch. This was using the load that I had worked up for my bolt gun, so it may get better if I changed my charge weight or even powder brand. Those groups were plenty good to bust up a coyote, so I quit while I was ahead!
Link Posted: 7/22/2008 3:28:55 PM EST
For anyone who cares....

Frank the owner of POF wrote me about my question. (I am buying his P-308 rifle with the 16.5"bbl).

He stated that they shoot some sort of McMillan match with the 14.5" version out to 600 yards and the 16.5" out to 920 yards.

I don't know if it will help anyone else here....just wanted to add that point.

Thanks,
Sean
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