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308 short barrel velocity

This is a discussion on 308 short barrel velocity within the Ammunition forums, part of the M14 M1A Forum category; Hello I'm starting to work with a new Scout Rifle with a 16.5" barrel. I've never owned a short barrel in 308, so the numbers ...


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Old March 18th, 2017, 08:44 AM   #1
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308 short barrel velocity

Hello


I'm starting to work with a new Scout Rifle with a 16.5" barrel. I've never owned a short barrel in 308, so the numbers are a little unfamiliar..

Starting out working with some 150gr FMJ loads for NATO spec duplication trying H-322, H-335, BL-C(2), Rx-15, IMR4895, IMR4064 and 748 with LC brass (pulled ammo with the military primer still in)..

Shot a 3 round group with some Winchester 150gr PowerPoint factory ammo, and it grouped into about 1' inches at 100 yards with an average velocity of 2575 fps. Also shot some PPU and PMC Bronze factory ammo and they both averaged 2532 and 2537 fps respectively.

In shooting some ladders with the above powders, velocities exceeded the recorded factory velocities into the low 2600's.

So.. Would I be correct in assuming that the Winchester factory load is loaded somewhere close to max working pressure,.. and the PPU and PMC loads are loaded to spec NATO pressure,, So any hand load I shoot that exceeds this velocity is probably over that pressure?

The only pressure indication I got was with 748 at 45.5grs I got a little bolt lift, so that one is obviously too far, but the others at the end of the ladder just got slightly cratered primers.

H-322 and H-335 is showing the most promise so far..

Thanks for the help

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Old March 18th, 2017, 02:16 PM   #2
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Higher velocity than factory with a similar bullet could mean more pressure or it could mean that your powder choice is giving you more speed. Honestly no way to tell. I also doubt that the factory ammo is loaded anywhere near "max pressure".

4895, RL15 and 4064 should give you the best velocities btw.

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Old March 18th, 2017, 02:27 PM   #3
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BLC-2 and 748 are on the slower side of the powders you listed and may or may not work so well with the 150's YMMV that's my .02 worth.. If it were I, I would stick with the mid-range powders for that barrel, IMR/H-4895.

Scout and Bush length rifles use a 18in barrel, its only the SOCCOM thing that uses the short 16in barrel.

While you do need x-amount of pressure too make your target velocity. Its assuming that you need X amount too get there isn't always the case its also the powders burning duration that will get you into real trouble.

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Old March 18th, 2017, 03:03 PM   #4
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http://rifleshooter.com/2016/02/308-...-308-bolt-gun/
http://bulletin.accurateshooter.com/...barrel-length/
http://www.thetruthaboutguns.com/201...-and-accuracy/

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Old March 18th, 2017, 04:11 PM   #5
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Ok thanks, I'll carry on and see how it goes..

POLACK that was just what I was looking around for.. thanks

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Old March 18th, 2017, 04:44 PM   #6
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Try IMR-3031. It burns faster and will be more efficient in a shorter barrel rifle.

Tony.

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Old March 18th, 2017, 07:52 PM   #7
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On 145-150 grain projectiles, 2550-2600 fps. seems to hit the accuracy node for my Socom 16.
As mentioned by Tonyben, and I will reiterate. IMR 3031 powder has been the most efficient powder for said weight projectiles that I have run in my Socom 16.
IMR 3031 gives a great blend of powder weight/velocity/pressure curve for the Socom 16's barrel length.
Another powder I like is Ramshot TAC.
To be Honest, I would not push the velocities of 145-150 grain bullets over 2600 fps.
Unfortunately I don't have Quickload to give an idea of the pressure of loads.
We had a former member here that helped me in that department.

Glenn

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Old March 18th, 2017, 08:13 PM   #8
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Hey GeePee, I do have some 3031 so I'll load some up. Also wanted to try some Benchmark, so we'll see.. Thanks

He he.. just figured out what that little 'thanks' tab is for... New here...

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Old March 18th, 2017, 08:33 PM   #9
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3031 isn't going to go any faster than 4064 just because your barrel is short, it will take 2-3 grains less per load though. I loved my 14.5" PWS 308 but california laws changing made it too much of a PITA otherwise I'd have kept it.

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Old March 18th, 2017, 09:42 PM   #10
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if your going to make your own,good case gauge and good chronograph
what other 308's do you have?

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Old March 19th, 2017, 06:51 AM   #11
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Quote:
Originally Posted by noob14s View Post
3031 isn't going to go any faster than 4064 just because your barrel is short, it will take 2-3 grains less per load though. I loved my 14.5" PWS 308 but california laws changing made it too much of a PITA otherwise I'd have kept it.
Your right, IMR 4895, H4895, RL 15 and IMR 4064 will get you velocities equal to IMR 3031 with the 145-150 grain projectiles.
And as you mentioned, IMR 3031 does it at a lower charge weight.
That is one reason I make sure to I say the most efficient, not the fastest.
Other benefits are a slightly lower pressure curve and less of a flash signature.
It is interesting to me that manufactured .308/7.62 ammunition will produce a good flash at the end of my Socom 16's barrel. But my hand loads using IMR 3031 don't.
When hunting at dawn or dusk, the lower flash signature is a plus in my book.
Just stuff for the OP to think about.

Too bad you had to get rid of your 14.5" PWS .308 because of Commie-fornia law!
I understand PWS makes a heck of an AR.

Thanks,
Glenn

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Old March 19th, 2017, 07:06 AM   #12
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Here's a good read...
Handload Recipie For Socom 16

Tony.

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Old March 19th, 2017, 08:33 AM   #13
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Sure miss RAMMAC's expertise.

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Old March 19th, 2017, 09:05 AM   #14
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tonyben.. Thats a lot of material! .. gemmie a few minutes to go through it..

POLACK I have a shooting buddy that has a 22" Mod 70...

I've loaded for the .358 Win for a long time and 3031 has been a top performer there as well.. same case just a fatter bullet..

It seems, from the little I've found out so far, that the short barrel is a velocity equalizer.. in that no one powder is going to excel over any other as velocity is concerned. But,,, I did notice that I got more velocity with H-322 than anything else I've tried so far, and that is a fairly fast powder.

Also interesting is the most accurate 147 FMJ factory ammo (PMC Bronze) is loaded with 41.8 grs of a ball powder. Never used IMR8208, but I wonder if this powder is very close to that burn speed..

Got some reading to do..

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Old March 19th, 2017, 01:04 PM   #15
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Powder burn rate spreadsheet here...
https://www.wwpowder.com/PDF/Burn%20...02015-2016.pdf

8208 is just a tad faster than 4895.

Tony.

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