Home Forums Hunting & Shooting Ask The Gunwriters chronograph reading diagnosis- 308 loads

My pet .308 load is 45.5 grains of Varget, winchester brass, WLR primer, and a 165 NBT or Sierra BTSP. Out of a 98 Mauser with 22 inch Wilson barrel she get @ 2650-2725. I do not sweat the velocity as he will shoot bug sized groups and kill well out as far as I care to take game.
The best I have ever gotten out of 150's from this rig was @2800 with a max dose of IMR4320. It was fast but I would rather have bullet weight than the little extra speed. The 165/168 grain bullets hit a sweet spot in the .308 for me. They fly plenty flat, are very stable, and usually outshoot 150's in the .308's I have shot. Particularly at distances over 200 yards.

Cloudy.

lots of good reading here since i posted

Miles- I think I may end up at 45 grns but we will see

MuleDeer- The cronograph was in the shade with the plastics shades on because I though the white background would allow the screens to pick up better.

Thats interesting that you found Hornady to produce lower pressure, because the Hornady data runs milder loads of Varget than other data like barnes, Hogdon and Speer for intace max out at 47 grns where Hornady data stops at 44.8 grn with 150's.

But that does explain the results

SuperT- its the cheapest Chrony and last year seemed to be in line checking 17 HMR ammo, but for kicks and giggles I may buy a box of factory 308's just to see.

It seems nothing is wrong so 45 grns at 2680 will make me happy for deer and black bear in places I hunt.

But I'm still going to re-shoot 45 grn and 46 grns Varget just to satisfy my curiosity

If I might make a suggestion, shoot more than two shots of each. If the true velocities of the different loads are close, it will take a larger sample to detect the difference.

My South Carolina (I think, new anyway) M-70 Fwt 308, 22" barrel produces 2743 with 46.0 Varget, Win WLR primer, Win brass and a Sierra 150 flat base. Hornady bullets produce less pressure in both the 308 and 7mm08 for me, based on both speed and primer flatness. This over an old Pact Chrono/Timer with diffusers over the screens. I need to start recording the cloud conditions when I chronograph.

Yeah, it helps.

I record everything I can about conditions during any range session, including temperature, wind direction and velocity (taken with a Kestrel), whether I put out wind flags, which chronograph was used, the scope, how many shots had been fired from the rifle since the last cleaning, etc. etc. Oh, and I also check the actual distance to the target with a laser rangefinder. It's kind of a PITA but quite often the info is useful.

This is the correct response. Your sample study is far from being statistically valid. Not meant to flame, but you need more data before you can draw any conclusions. I collect chrony data every time I am out to make sure things remain consistent.

yup, thats why I will shoot more, but did not want to load up 10 rounds of each load if there was a potential problem.

ruger438, please let us know how things turn out.

SuperT-FWIW,finally got a chance to re-shoot some over the chrony.

Also bought a box of Federal Blue box 150's as a reference

10 shots each, cloudy this time with diffusers up 22" 70 Featherweight 308.

Federal Factory Load 150grn
2733-2761 ave. 2744

150 Hornady Interloc BTSP
44 grn Varget
2563-2612 ave 2591

45 grn Varget
2643-2702 ave 2683

46 grn Varget
2712-2751 ave 2719

All loads shot well 1- 1 1/4, smallest was the 44 grn load and Federal factory load.

Cloudy conditions seem to have given better results with the chrony, so I was fun to experiment a little.

Now after all that fooling around I am sticking with the original 44 grn load since it does kick noticeably less and have enough ooomph to pop deer.

Why not just stay with the factory stuff?

Because of the red highlighted line, and I have thought a 300 Savage would be about right.

Likely doesn't matter but notice that at pushing 4000 feet toward the headwaters of the Missouri air pressure equivalent to 14.7 psi at sea level works out closer to 12.7 psi - this might change external ballistics some along with the presence or absence of humidity (hydrogen is a light gas) so even results fired at the same spot might vary between a dry winter and a hot wetter summer.

Maybe we could have a predicted velocity rifle match for those of us loonies who can't shoot for accuracy?

FWIW, I just found a good long range target load of the Nosler 168 BTHP and 46.0g of Varget, which I chronographed at 2740 fps from my 26" barrel.

GPerry

Wow, some of you really need to look in the mirror and realize that what's printed in a reloading book or posted on a forum is not the end all, be all, of velocities.

99% of you shoot off the rack hunting rifles. The bullet velocities will vary by several hundred fps because of the chamber size, free bore, barrel diameter, bullet, primer, brand of case used, how far from the nuzzle you measure the velocity, elevation, air density etc.

For Christ's sakes, lighten up!

When I started using Re 15 in the 303 British and 308 Win/7.62 x51mm in 1999, I found big differences between rifles from different manufacturers. I did not believe that there was a problem; just variances between rifles.

Relax. A 100 or 200 fps swing does not mean that there's something wrong with your rifle, barrel or recipe.

We now return you to your regularly scheduled (ill informed) discussion.

Ruger
I own a 1963 FW 308. I did the same as you and used a factory load to establish a baseline and went from there with 150 gr bullets.
Where I live in New England there have been many volumes of deer that died quite nicely from 30-30s. So I loaded up what shot well and went hunting. Same choice as you. The slower loads looked good on paper. No need to kick myself silly on a 150 yard or under shot that is all I will see in my rifle hunting here.
It even worked in East Texas when I had the lucky chance to hunt Hogs for 7 days on a really nice property. Every hog that a bullet hit in the front 1\3rd died within 40 yds of where it was hit. (These were 06 rounds out of a push feed model 70, but at the same speed as my 308 loads).
No knock on going faster. Just an example of 1 that found dead game at the end of the day with speed closer to some of the old classic rounds.
I like knowing what the speed is but dont need it to be max to hunt deer here.
Enjoy your fall hunting.

Ruger, my old Mauser 308 has a 24 inch barrel. I shoot 44g of AR2208/Varget over 150g bullets, including Corelokt and Interlock.

I get ave 2575fps consistently. So your results don't surprise me at all.

Factory ammo eg 150g Corlokt chronies right on the advertised 2800+ fps. I just think the 44g figures in the Hodgdon/ADI data are not all that relative to some rifles.

That's the beauty of a chrony - now we know.

seems like I've read this thread before - anyway, 47.3 or 47.5 gr of Varget work great for me with 150 gr Horn SP and also Barnes TTSX. The 165 gr load that works best in my 308 is 50.0 gr 2000MR at about 2830 fps using either 165 gr Fusions or 165 gr Interbonds. Great velocity and accuracy with both. I am currently using my 284 win shooting 120 gr NBT's into itty bitty groups as my longer range round and the 308 shooting the 165 IB as my woods stand load. Great thing about hunting here in Mid-MO, you have a pretty good idea of what you can expect for shot length, based on which stand you hunt.

Fwiw...my factory rem vtr has a ton of jump to the rifling. When I combo this with generous room in win brass I need about 2 grains more powder than much data I see in manuals and the inet.