REPR 16" v. 20" velocities????

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Postby borebrush » Tue Apr 27, 2010 12:17 am

dont confuse a cheap barrel receiver interface for barrel whip.

The entire AK does the shimmy.


this whole discussion is way over heads here.


Shorter barrels dont shoot better than longer barrels. That's a simplistic way to put it and its quite untrue.


EVERY REPR thread I have said this. The Optimal bbl length for .308 is 22-24". 20 is as short as I'd ever go on a precision gun. Without velocity, there is no accuracy. BBL whip or not.


There are so many facets to designing and building a weapon. Y'all are getting wrapped in the spokes over barrel whip. Arguing accuracy with people who think neutered .308s are better because they have short thingies.


Barrel whip means jack squat because the barrel is releasing the bullet in the same place every time. It's free floated, and bbl whip is over before the next shot.

Minutiae.
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Postby eazenutz33 » Tue Apr 27, 2010 12:38 am

borebrush wrote:dont confuse a cheap barrel receiver interface for barrel whip.

The entire AK does the shimmy.


this whole discussion is way over heads here.


Shorter barrels dont shoot better than longer barrels. That's a simplistic way to put it and its quite untrue.


EVERY REPR thread I have said this. The Optimal bbl length for .308 is 22-24". 20 is as short as I'd ever go on a precision gun. Without velocity, there is no accuracy. BBL whip or not.


There are so many facets to designing and building a weapon. Y'all are getting wrapped in the spokes over barrel whip. Arguing accuracy with people who think neutered .308s are better because they have short thingies.


Barrel whip means jack squat because the barrel is releasing the bullet in the same place every time. It's free floated, and bbl whip is over before the next shot.

Minutiae.


Forget barrel whip then....its a minor concern, if any, on this type of weapon anyways......

VELOCITY is something you pointed out......which was my concern about ordering a 16" v. a 20" ......with the 20" and a silencer it can get rather long and cumbersome ......a 16" with silencer is more manageable.

If the VELOCITY difference is almost nothing from a silenced 16" compared to a 20" without silencer.......then wouldn't the advantage go to the 16" silenced weapon????

I know you're saying the optimum barrel length is 22-24"......but 22-24" WITH a silencer is ignorant in length, I mounted my M4-2000 to the 24" AR I had and it was like carrying a flag pole around! Considering a maximum range of lets say 600 yards, with a more likely maximum range of around 400-450 yards, a common range within 250-300 yards.......would a silenced 16" REPR not be on the same level as a non-silenced 20" REPR???
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Postby FA sear » Tue Apr 27, 2010 12:19 pm

eazenutz33 wrote:
FA sear wrote:
eazenutz33 wrote:was my understanding that ALL barrels will experience "whip".......tho heavier profile, shorter length, and so on will reduce it to near zero amounts depending on caliber.....why you might find an extra heavy bull barrel for .223 or even on rifles like my savage .17hmr


That is not what I was taught, nor have seen. The last point you bring up is part of the issue, but the material of the barrel also has an influence. I also thought barrel whip was a major issue, that is until a coworker of mine showed me a video of various guns being fired in super slow motion. It was a very long time ago (yes the film was on a reel), but as I remember, they fired an AK, FAL, M16, M14, and I don't remember the last couple of guns. Barrel whip was not that prominent on most of the guns (except the AK), and not even visible on one of the guns. None of the guns had a heavy barrel, and all of them were fired on full auto.
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Postby Twitchy » Fri Apr 30, 2010 5:49 pm

Just chrono'd my REPR 16 with a SAS suppressor (gas block to S) and got an average of 2350fps using FGMM 175's.

Perhaps I need to confirm on another chrono.

Has anyone tested with the gas block closed to see if that makes a noticeable difference in the fps?
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Re: REPR 16" v. 20" velocities????

Postby K_4c » Tue Oct 19, 2010 11:54 pm

I gotta bring this thread back to life! I've notice after 400 rds down the tube of my REPR (20") it is now shooting FMMG 168's at 2540+/- 22 fps (from 2500 on the high end)..... anymore data from other users would be great to confirm this.

Thanks much
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Re: REPR 16" v. 20" velocities????

Postby criticalw88 » Mon Jan 24, 2011 1:44 am

It would seem like LWRC should offer a 24" barrel length (with flutes). I wonder if they would ever offer such a barrel.
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Re: REPR 16" v. 20" velocities????

Postby Lofty » Fri Jan 28, 2011 7:02 pm

All barrels "whip", even a huge barrel on a .50 BMG will.

The key to accuracy is will it whip the same way every time. That's why a barrel needs to free float, so nothing interferes with the barrels movement and and can react the same way every time and release the bullet from the muzzle the same place in it's whip evrytime.

Maybe 22/24 inches is ideal when considering long range accuracy as it's primary function, but a weapons primary usage has to be considered. I would say the 7.62 has superior ballistics over the 5.56 even in shorter barrel configurations....so for CQB work, or for that matter, anything out to 300 yards, a 12.7 upper would be just fine against small targets.

Barrel length doesn't affect accuracy until you getbto longer ranges and the reduced velocity cause the bullet to go trans sonic sooner.

I had a 7.5 inch Noveske upper on my SBR that would shoot sub MOA with good ammo. As long as the bullet made a complete rotation before exiting, I don't see how longer barrel has an advantage in accuracy within 300 yards or so.


But that's the nice thing about the platform, swap out uppers and you're good for both.
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Re: REPR 16" v. 20" velocities????

Postby Sierra 1 » Mon Feb 28, 2011 3:59 pm

For what it is worth we shot a 12" .308 gas gun out to 920 yards with 175 gr bullets in a sniper instructor school I attended last year. I would not of believed it if I had not done it. 5 people shot the instructors gun at the target and once the spotter had the wind called right everyone was getting consistent hits on the target that was the size of a three day assault pack. I saw bolt guns that were cut to 16 inches with a hack saw and no crown engage targets out to 1300 yards. From this experience I think in the .308, barrel length is over rated. IMO
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Re: REPR 16" v. 20" velocities????

Postby gus7 » Thu Mar 03, 2011 12:42 am

Sierra 1 wrote:For what it is worth we shot a 12" .308 gas gun out to 920 yards with 175 gr bullets in a sniper instructor school I attended last year. I would not of believed it if I had not done it. 5 people shot the instructors gun at the target and once the spotter had the wind called right everyone was getting consistent hits on the target that was the size of a three day assault pack. I saw bolt guns that were cut to 16 inches with a hack saw and no crown engage targets out to 1300 yards. From this experience I think in the .308, barrel length is over rated. IMO

back in ft.benning this was done 1980's i seen it too .i liked the 18'' barrel the most a very happy balance with performance and weight with 2500 fps ave the goal ....16 can do and work out to 600yds easy ..but always remember the 308 on most part goes under the sonic at app. 850 yds plus the more range the wind will play hell too more so ..........
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Re: REPR 16" v. 20" velocities????

Postby Masterfreak19Delta » Thu Dec 08, 2016 3:56 pm

My 18" REPR chronos 2465 fps with 175 FGM at 400 ft elevation.
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Re:

Postby charliebrn » Sat Feb 25, 2017 11:45 pm

borebrush wrote:guys...

22-24" is optimal for .308


Knowing what I know, and balancing it all out. I'd never go below a 20 with a .308.


I've covered the reasons why in other threads.


Out to 400yds with a scoped rifle, I am faster and deadlier with a 5.56 SPR.


Realise that wind is no value on 5.56 until 300yds. Shot to Shot recovery is faster.... 5.56 if is a sub-600yd issue.


for LR work... there is no reason to need a short bbl. 165s are transonic at about 700. So that means you'll need the 175s (M118LR) for the extended range. That shite is made for 24" bbl's.

If you want precision it makes no sense to get a 16" gun. Frig... here I am repeating myself.


Borebrush,

Thank you for your link to your earlier discussion.. you mentioned in that thread that M80 ball is even bad for your rifle... why is that? I've stayed away from any steel but have a lot of M80 sitting and waiting for play time. I have a bunch of GMM too, but thought the M80 was gtg, so what's the issue with it?

It was a great read, thanks again...
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