Min load data for Sierra .308 168GR TMK

[juststarting]

Hi All

Am trying to find min load data, using AR2208 for Sierra .308 168GR TMK (Sierra 30 CAL .308DIA 168GR TMK #7768).

Nick Harvey's manual suggests 42GR for 165-168GR projectiles, doesn't indicate specifically which projectile though.

Closest I could find to that, is ADI - also 42GR for 168GR projectile using AR2208, but for 168GR SIE HPBT. Speer manual, also has HPBT, using Varget (same I am lead to believe), not TMK though, also at 42GR; and Lee - also 42GR for a 168GR jacketed bullet.

Just wanted to confirm, if 42GR is the right load? Suggestions?


Thanks

[happyhunter]

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[juststarting]

Thanks.

I have 1:11, though from everything I've read just now, it doesn't seem overly important.

[happyhunter]

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[Baronvonrort]

Go with the Sierra data for Varget, they made the projectile, I would start with 39gr

[juststarting]

Thanks.

I did go with Sierra data. I started with 38.7 though. Have not tested yet.

[Bourt]

Is there a reason you're really focussed on min load?

Trying to do a low recoil one?

[juststarting]

No, trying to understand load and work up. Understanding the minimum sets a baseline.

[happyhunter]

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[Bourt]

No, trying to understand load and work up. Understanding the minimum sets a baseline.

Sure mate. Hope it didn't sound like I was having a go. I wasn't.

I sort of meant to say just remember there is a safety margin in the data manufacturers will provide.

e.g. ADI state 41gr - 45gr of 2208 online for 168gr .308.

It doesn't mean 45gr is dancing with death and an extra 0.1gr will guarantee an explosion. I'm not suggesting you go over, just saying that in this example 45gr would be safe in any proven rifle using that data.

If not doing a low-recoil load I thought maybe you were worried about doing a mid-range load and were trying to load as little powder as possible due to safety worries?

[juststarting]

@happyhunter - haven't read it, but interesting. Always good to learn stuff

@Bourt - didn't read it that way at all. Quite the opposite, agreeing with you...
I was saying, someone here suggested load data from Sierra. It looked a lot more conservative than any other reference - for that specific projectile, so I decided to go with that value (38.7), rather than 41-42gr which was in every other manual for similar, but not the same, bullets. Being new to reloading, I am starting at minimum loads and then will be working up. First however I just need to be comfortable (get over the mental thing of making my own ammo), hence being as safe as I can be with minimum/conservative loads.

[happyhunter]

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[Baronvonrort]

I was saying, someone here suggested load data from Sierra. It looked a lot more conservative than any other reference - for that specific projectile, so I decided to go with that value (38.7), rather than 41-42gr which was in every other manual for similar, but not the same, bullets.

Whenever possible use load data for a specific projectile as the starting point
The loads will vary with projectile types of the same weight, many variables from BT to FB along with seating depth which can affect case volume which will affect pressure.

The aim of load development is to find out what load is the most accurate, some say vibrations and harmonics of the rifle/stock need to be in tune with the bang from the powder,others say it helps if the projectile leaves the barrel at 12 or 6 o clock instead of 3 or 9 clock which scatters them wider.
Whatever reasons people give it does work out individual rifles prefer some loads for best accuracy, you will end up doing this with each type of new projectile you get so keep records of what you do.

The projectile you chose looks good nice BC , don't be afraid to post some pics.

[juststarting]

Did I not just say that?

[BBJ]

Just remember also there is such a thing as too little powder.

Don't go any lower than the minimum thinking the less powder in the case the safer it gets, that isn't the case.

Especially with slow burning powders and larger cases too little power, not filling a sufficient amount of the case capacity, can mean pressure spikes or detonation instead of a burning column of powder.

Just remember to be safe on the lower end of the scale too

[happyhunter]

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[juststarting]

Reporting live, from the range, 38.7 is waaay too low, hits low at 100m, but consistent. :/

[sandgroperbill]

let us know the grouping size when you can

[sarki]

Yeah not sure what that means.

Low but consistent?

Dropping lots but accurate you mean?

or just consistently bad?

[juststarting]

Sorry, should've been more descriptive. Dropping lots, I think. Also I am not the best shot, so, could be me, but they do hit lower than factory rounds. Group was okay though (for me), will post more details when I get home.

[sandgroperbill]

More likely a different point of impact to your factory rounds. I wouldn't translate a lower point of impact to a weak load until you start pushing it out to further distances

[happyhunter]

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[Harper]

Dropping lots, I think. Also I am not the best shot, so, could be me, but they do hit lower than factory rounds. Group was okay though (for me), will post more details when I get home.

Likely that the factory loads would be 100-150 fps faster than your starting load so a lower POI would make some sense.

[juststarting]

let us know the grouping size when you can

Here you go:
http://myshootingjourney.com/2015/11/26 ... er-groups/

[bigtone]

I use the 168 grain Sierra projectiles in both my 308s and in my 300 winmag. 46 grains of 2208 flattens the primers pretty well but also sometimes jams my pump action due to cases getting stuck. I found that dropping back to 45 grains stops the jamming in the pumpy and still shoots out accurately at distance in my Sako. If you are trying to save a bit of cash then try 2206h. You can achieve similar muzzle velocities with a bit less powder so you might save a few bucks if you do heaps of shooting.

[BBJ]

Not a bad clover (excluding the flyer) on the top left there.

[juststarting]

Thank BBJ, once is a fluke I'll post again next week, will see if I can repeat this with consistency.

[Korkt]

will see if I can repeat this with consistency.

Practice makes perfect