How Much Does Barrel Length Affect .308/7.62NATO Bullet Velocity?

7.62×39 or 300 blackout

I want to see this exact same video with all the same guns and use .308 to see how the velocity compares to the 7.62×51.

22lr out of a 34 inch barrel

Once I saw kaydi I never heard anything what's his name said😍⚘

What was ambient temp of air/ammo?…at what altitude?

Thinking about getting a ruger SFAR 16" and cutting the barrel to pin and weld a deadair keymo for true 16" afterwords, to host a Deadair Sandman L, seems like 16" to 14.5" or so wouldn't be too much of a difference.

@9:45 her face though…

Bet 300blk, 8.6blk, 6.5cred, and a few others might slow down in the barrel

There are; pistol caliber carbines.

Interesting results. I was thinking about purchasing a Ruger SFAR with a 20 inch barrel for hunting. Thinking it would offer better velocity & accuracy. Might have just changed my mind about that. And I’m-now thinking the 16 inch barrel would be a better choice for weight savings and maneuvering in the woods.

Thanks.

So much good and interesting info just to have your wife hovering her trigger finger over the trigger as you banter about your give away.

6.5 creedmoor from a 26 heavy varmint barrel

Yoiu should have shown the averages in writing. Not clear enough when spoken only. Good show..

I came across this from another channel. That guy tested 308vs762 in STEEL. 7.62 carved out a deeper trench in the 1/2 plate. One of his followers wrote this. I didn't grab the persons name, sad to say to give them credit.

One of the replies in comments on the video 7.62 NATO vs. 308Win

I was in the military, specializing in armaments. The military literature mentioned that the 7.62 max pressure was 55,000 psi. If you read deeper into the file, it also mentioned that pressure was measured with copper crusher method. Now referred to as CUP. later, when transducers become the standard way to measure pressure, the industry adopted the system of referring to pressures as either CUP or psi.

The military reference to 55,000 psi has caused many to believe that 7.62×51 is loaded to a lower pressure. No so. The limits for 308 and 7.62 are about the same – about 62,000 psi, as measured with a transducer.

In practice, ammo of both flavours is typically around 56,000 psi, although I have found a few lots of 308 (Winchester Supreme match and IVI Lot 631) at 62,000 psi. Both were tested because they were causing problems in some rifles.

The testing handbook specifies where the chamber pressure is to be measured. It varies from caliber to caliber. And sometimes (as in 7.62 -308) the place the pressure is measured is different in the two systems. If the place of measurement is the same, you can convert CUP to PSI mathematically, like converting MPH to KPH. But if the place of measurement is different, the two values bear no relationship to each other.

There are some difference in the ammo specs – SAAMI vs. Military. The military case has a stronger, harder case head, so as to withstand violent extraction of automatic rifles. Military ammo has a muzzle flash spec. SAAMI does not. Military ammo will have a sealant in the neck. SAAMI does not.

The lead core can vary in antimony content (hardness) and jacket thickness can vary as well, with military bullets being hard and commercial ammo being anything the maker finds easy to make.

This test I watched just compared two different brands of ammo and assumed that the difference was due to NATO v Commercial. Not so. Just brand A v brand B

i had a 26 inch barrel AR10 308 and it was fairly accurate at least to 400-500 yrds but it was also heavy!
11 lbs plus scope was about 13
it was restricted in canada so it was a range gun only
luckily i sold it for same money i bought it for and got a non resrticted rifle with 20 inch barrel for hunting thats way lighter & more accurate too

.300 Blackout

.357 magnum is perfect through a 16" barrel, anything longer its starts getting barrel drag…but its a pistol cartridge.

I run a 28" on my F-TR rifle, and I get about 50-80fps faster velocities than my 24" barrel on the same platform. The 308 has a mid-rate burning powder profile and that creates a faster MV as the barrel gets longer. I'd like to see a 26" and 28" barrel added onto the test just to see if you get a similar result. I am shooting a much heavier projectile though, 168gn – 208gn. MDT did a test for length of barrel to velocity comparison. They started out with a very, extremely, wildly, in-the-next-zip-code barrel length and cut it back. I think it was like 31 or 33" was optimal for calibers in the range of the 308.

I have clocked 2600 fps with 150 grain bullets out of my 16"5 .308.

So he's going to do all the shooting? Selfish

That's what she said!

Does 9 mm slow down in a 16 in barrel

Seriously why is she on this video what the….

Got to love these YouTubers who bring on the token female for God knows what purpose other than to have a bunch of cringe moments in the middle of the video. Thank you for all those awkward pauses

2676.3 fps 16in
2642.3 fps 16in suppressed
2714 fps 18in
2774 fps 20 inch

some averages for the few that just about these lengths
18.85 feet per inch between 16 inch and 18 inch unsuppressed
30 feet per inch between 18 inch and 20 inch

I bet Clints wife is super stoked he's hanging out with Kaydi as much as he is.

I hoped to see Katie shoot
But maybe next time

That little dsa seems to underperform 300blk supers

Katie is sooo fine 🙂 👌 👍 🙂!!!!! Just saying 😉

.308 AR 10 eighteen -inch barrel length is pretty good overall.

I’d say to a long barrel test on 300 black out. If they make long barbells past 16”.

Try same gun with different surpressors, I'll bet you get different velocities.

I think Hornady or Nosler shows the .308 with a 110 grain bullet pushing near 3200fps.
The .308 has thinner brass, so it has more powder capacity.

Those two rounds are not quite the same and the chambers usually vary too. DSA uses a true .308 for their SA58 match rifles, IIRC. And of course if you close the gas port, you turn it into a higher pressure bolt action rifle.

REAPER (Rapid Engagement Precision Rifle) hmmm 🤔 I don’t think they can spell.

@09:47 that look on her face is priceless

Wish you would have posted a graph or at least a table at the end recapping the results. Also would have been nice to continue showing the averages like you did on the first one.

miss you kaydi. have fun be safe.

That is a pretty beast mode rifle

i want to see the same test but for 6.5 grendel🎃

The one God gave me

I could be happy with a 16 inch, at 8 inch I’d rather go with .300 BLK or 7.62×39

The 16" seems to have the best velocity for the barrel length.
Putting an extra 6 inches on the barrel just to get another 100 fps just seems downright silly.

5.7×28