What's your 20" .308 barrel FPS?

[Sebben]

Tuesday I'm heading off to the range to do some load development and also I'll be testing FPS/consistence of both hand loads and some factory ammo. So for those of you with 20" bbl 308s what velocity do you get with 168, 175 FGMMs and 168 Hornady TAP?

 

[BCP]

Re: What's your 20" .308 barrel FPS?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Sebben</div><div class="ubbcode-body">168, 175 FGMM
</div></div>

Just under 2600 for both out of a rem LTR.

 

[K_4c]

Re: What's your 20" .308 barrel FPS?

Larue OBR 20"
CFE223:45.3 gr
175 SMK
Lupua brass
CCI 200
2.800"
2640 fps @1191 altitude
ES: 12-22 fps through 5 strings

 

[Niles Coyote]

Re: What's your 20" .308 barrel FPS?

Not an auto, but 20" rem tact,
44.5 varget and 175smk w/Win brass and primer = 2550
168 amax 45.8 varget w/Win brass and primer = 2675

These were collected 15' from the muzzle.

 

[ccoker]

Re: What's your 20" .308 barrel FPS?

20" LTR
2575 FPS 175 SMK
44.2g Varget

 

[Pusher591]

Re: What's your 20" .308 barrel FPS?

Guys, Im pretty sure he's wanting semi-auto readings because usually the gas guns run a little less then the bolts.

I'm intrested as well, I'm trying to make the decision now between 18" or 20". If there's not that big a difference I'm gonna go 18".

 

[PhrogDriver]

Re: What's your 20" .308 barrel FPS?

GAP .308 AR with 18" Bartlein 1/11.25R, Thruster muzzle brake, ammo and ambient temp 64 deg F, CED M2 chronograph, 15' from muzzle:

Fed GMM 168: 2558 fps
Fed GMM 175: 2574 fps

No idea why the 175's are slightly faster, but it is what it is...

 

[Sebben]

Re: What's your 20" .308 barrel FPS?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Pusher591</div><div class="ubbcode-body">Guys, Im pretty sure he's wanting semi-auto readings because usually the gas guns run a little less then the bolts.

I'm intrested as well, I'm trying to make the decision now between 18" or 20". If there's not that big a difference I'm gonna go 18". </div></div>

Actually both will work. My friend is doing the same thing with his Remington 700 AAC SD 20" so either Bolt or semi data is much appreciated.

Also with this comparison we will be able to see if bolts do have a velocity advantage over semis. Personally I don't think they do.

 

[Niles Coyote]

Re: What's your 20" .308 barrel FPS?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Sebben</div><div class="ubbcode-body"> we will be able to see if bolts do have a velocity advantage over semis. Personally I don't think they do.</div></div>

I am beginning to wonder the same.

 

[SD26]

Re: What's your 20" .308 barrel FPS?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Sebben</div><div class="ubbcode-body">
Also with this comparison we will be able to see if bolts do have a velocity advantage over semis. Personally I don't think they do.
</div></div>
Was wondering the same thing myself the other day...

 

[RG in Idaho]

Re: What's your 20" .308 barrel FPS?

LMT 20" SS, 1:11.25
175gr FGMM 7.62x51
2654fps @ 2450'asl

 

[Pusher591]

Re: What's your 20" .308 barrel FPS?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Niles Coyote</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Sebben</div><div class="ubbcode-body"> we will be able to see if bolts do have a velocity advantage over semis. Personally I don't think they do.</div></div>

I am beginning to wonder the same. </div></div>

I've seen it first hand, MOST the time a custom barrel AR10 will run slightly slower then the same length custom barreled bolt guns.

It's my opinion, but that seems reasonable they would be slightly slower due to a little less pressure due to the gas system using that pressure to manipulate the BCG/Bolt so it can chamber the next round.

 

[Pusher591]

Re: What's your 20" .308 barrel FPS?

Let me add to the above as well that it's seems gas guns cannot run some hot loads that the bolt guns can, that can add to the equation of not reaching the same fps number.

Neither of these may be completely correct but I think they play a role in it.