Low velocity .308 loads

[Gryphon Energetics]

Hello all,

We have a need for some lower velocity .308 loads to conduct product testing to emulate the 7.62x39 but with greater accuracy than most rifles in that caliber tend to offer. By downloading a .308 it provides us velocity flexibility in a single platform capable of high accuracy at all distances.

Does anyone have some loads or suggestions to get a 125gr .308 down to around the 2000-2300 fps range? Case capacity on the .308 is obviously much larger than the 7.62x39 so a voluminous powder is preferable, but Trail Boss is too voluminous as IMR states the max load of 14 gr only gives some 1400 fps.

 

[Camaroguy]

Try finding loads using IMR SR4759. I don't have any load data for 308, but I seem to recall there being load data for it in the same article I found my 30-06 data.

 

[Gryphon Energetics]

Actually I just looked up the specs for the .30-30 Winchester which is often stated to be a close ballistic equivalent of the 7.62x39 and its case is almost identical in length to the .308 Winchester. Seems that I'll be able to use any .30-30 load data to achieve these results.

 

[sunray]

Do not use .30-30 data. It's not even close to the .308. Think in terms of a cast bullet instead.

 

[Trinimon]

Use caution when trying to find reduced loads. I believe you'll be hitting possible secondary explosion mark when using slower burning powder below the 15% max recommended load.

 

[Outwest1213]

Does the grain weight have to match the 7.62x39 or are u just looking for velocity to be about the same. I have 170 grain .308 at 2000 fps. I don't have any load data that would put a .308 125 grain bullet under 2700 fps.

 

[Easy 9mm]

Just Google 308 reduced loads.

Although I haven't actually tried these, the info may still be of help to you.

From www.chuckhawks.com/reduced_recoil_reloads.htm

.308 Winchester - 130 grain Speer HP bullet, 29.0 grains of IMR 4198, CCI 200 primer, IMI case, COL 2.615". MV 2185 fps in 22" barrel. (Based on the Speer Reloading Manual No. 13.)

 

[Tick]

Use the 60% rule for Hodgdon's H4895 No pressure problems and consistent burn rates. Its in their manuals and on their web site.

 

[Gryphon Energetics]

Thanks fellas!

I would prefer to keep the bullet weight and velocity the same so the energy on target is roughly equivalent. Given the high popularity and availability of SKS rifles and the ammunition we want to ensure this popular combo is compatible with our products. I suppose I could always use the excuse to buy a more precise rifle than an SKS to do testing but there aren't a lot of options in that caliber.

So far we have tested our targets with full power .308 Winchester, .223 Remington, and 7.62x39 surplus. All detonated at up to 200 meters. We would like to conduct more long range testing and that's where precision becomes more important, and an SKS - while a potentially accurate representation of real world usage - is not a practical delivery system for that kind of distance.

 

[Barnes_270]

Use the 60% rule for Hodgdon's H4895 No pressure problems and consistent burn rates. Its in their manuals and on their web site.

This. H4895 is your friend for this sort of thing. Google "Hodgdon Youth Loads" for a PDF.

 

[LUTNIT]

Use caution when trying to find reduced loads. I believe you'll be hitting possible secondary explosion mark when using slower burning powder below the 15% max recommended load.

The only ballistic lab in the world that has managed to recreate a SEE in laboratory settings is Norma and even they are only able to get it to happen around 1/3 of the time based on the information they published.
The only way they have gotten SEE's to happen at all (other labs have tried but none succeeded) was with a very light load of slow burning (magnum) rifle powder in a large volume case. Something like 60-70% empty space in the case.
Many believe that the vast majority of SEE's reported are actually barrel obstructions or double charges. A reloader can swear up and down that that isn't possible but the evidence has literally gone up in smoke.

As a rule I now only use magnum powders for full power loads where usually 90%+ of the case is filled. If I am doing reduced loads (such as .308 data in a .300WM) I use fast or medium burn powders.
As mentioned, H4895 has been used for reduced loads down to 60% of published data for decades.

 

[Ganderite]

Why not borrow an accurate 7.62x39? I built one specifically for testing ammo. Uses a heavy match 20" barrel. You are welcome to borrow it.

When my kids were young (10) they shot the Sierra 125 loaded with 3031. They shot in matches back to 600 yards. it was very accurate. Loads were too mild to shoot beyond 600.

 

[crashcollins]

I know it's not known as a precision gun but would a Rob Arms XCR in 7.62x39 work for what you need to do? The XCR should be more accurate then a milsurp SKS. If you were near me we might have been able to arrange a loan of my XCR but we are too far apart from each other. Maybe a CGN'r more local to you could help out.

 

[purple]

The Speer manual No 12 includes a .308 load with a 125gr bullet using 25-29gr IMR4198, MV 1969-2185. Why not use a 150 gr bullet which will shoot better in the .308? Speer uses 21-25gr SR4759, an old favourite for reduced loads, which gives a MV of 1632-1925. I've used this one in a number of .308s and .30-06 rifles; quiet, mild and accurate.