308 Load Development

[350 Mag]

I am not a fan of Lead Sleds unless your shooting a 338-378 Weatherby.

Point being, it might be to steady and too heavy of a shooting platform.

You want the rifle to free recoil, and sitting in a heavy lead sled the recoil is going to put "different" stress point on recoil lug.

You might develop an accurate load but under field conditions your grouping might change....poi shift or group might open up.

I like a high quality sand bag for rear and front. If I need more elevation I keep a couple boards to shim below bag.

If you use a bipod in field....make sure you develop your load off that bipod and keep the legs of the bipod loaded to front consistently so when it comes time to shoot in the field it's consistent.

 

[BCBRAD]

Is the rifle bedded? Accuracy and repeatability will suffer without good bedding.

Did you test up to around 46 gr of Varget? Your load looks mild. I would test higher until I got pressure signs, then drop a grain.

Many rifles will not display traditional pressure signs until you are in the 75,000 psi range, dropping one grain may not reduce the pressure into the safe zone, which is 62,000 max psi for the 308 Win.

Let velocity be your guide (velocity is a pressure sign) when using appropriate powders. The Nosler reloading manual, can get information on line as well , is a good one as it will state most accurate powder and charge weight with a variety of bullets.

To extrapolate the velocities from the 'test' barrel expect a velocity loss due to your short barrel, if it is 25 ft/s per inch and the reduction is 8", then the velocity loss will be 200 ft/s.

Noslers ' best load' is most certainly on a node for the components used. So if the book says 2800 ft/s best load then in and around 2600 ft/s would be an accurate load for your barrel length.

 

[doowroh]

Many rifles will not display traditional pressure signs until you are in the 75,000 psi range, dropping one grain may not reduce the pressure into the safe zone, which is 62,000 max psi for the 308 Win.

Let velocity be your guide (velocity is a pressure sign) when using appropriate powders. The Nosler reloading manual, can get information on line as well , is a good one as it will state most accurate powder and charge weight with a variety of bullets.

To extrapolate the velocities from the 'test' barrel expect a velocity loss due to your short barrel, if it is 25 ft/s per inch and the reduction is 8", then the velocity loss will be 200 ft/s.

Noslers ' best load' is most certainly on a node for the components used. So if the book says 2800 ft/s best load then in and around 2600 ft/s would be an accurate load for your barrel length.

That’s a really good point!!
I will try that, keeping in mind that YMMV and no two rifles tune the same, but the core of that logic sounds fantastically solid.

The problem that I have had with examples like this (which, may very well only be perceived problems) is that say I am a Sierra fan-boy, or my LGS doesn’t have any Nosler projectiles, I don’t feel entirely comfortable substituting a Hornady flat-base, or a Sierra HPBT for the listed (for example) Nosler Ballistic Tip bullet. I guess the answer is to back the charges down a bit and work up?... I’ve always heard that the differences in bearing surface between a flat-base and a boat tail can change pressures significantly.

Again, I tend to suffer from analysis paralysis when it comes to things like this, so maybe it’s just me, but I would love some insight on things like that.

 

[BCBRAD]

That’s a really good point!!
I will try that, keeping in mind that YMMV and no two rifles tune the same, but the core of that logic sounds fantastically solid.

The problem that I have had with examples like this (which, may very well only be perceived problems) is that say I am a Sierra fan-boy, or my LGS doesn’t have any Nosler projectiles, I don’t feel entirely comfortable substituting a Hornady flat-base, or a Sierra HPBT for the listed (for example) Nosler Ballistic Tip bullet. I guess the answer is to back the charges down a bit and work up?... I’ve always heard that the differences in bearing surface between a flat-base and a boat tail can change pressures significantly.

Again, I tend to suffer from analysis paralysis when it comes to things like this, so maybe it’s just me, but I would love some insight on things like that.

Check the Sierra online load manual https://sierrabulletsblog.com/2018/01/31/sierra-bullets-load-data-for-2018-new-matchking-bullets/

 

[noelb]

I just bought the same rifle and plan to reload for hunting as well. Great post.

 

[bc7mm]

Have you tried adjusting your OAL? How far off the lands is the bullet. I have found a few rifles over the years where this tightened the groups quite a bit. Some have more free Bore. Be cautious as you increase your OAL as it will effect pressures.

 

[Ganderite]

Have you tried adjusting your OAL? How far off the lands is the bullet. I have found a few rifles over the years where this tightened the groups quite a bit. Some have more free Bore. Be cautious as you increase your OAL as it will effect pressures.

I was wondering the same thing. Your OAL looks kinda short.

I suggest the bullet 20 thou off the rifling, to start.

 

[cosmic]

As you stated, your rifle seems to prefer ~ 165 grainers - stick with that weight. My own experience shows that, in many cases, flat based bullets shoot better than boat-tails. As this is a hunting load for deer, I dont see any disadvantage in using flat based bullets for the distance you are shooting. Of course, match bullets are generally boat-tails, but they are made to a higher standard of tolerance that the normal hunting boat tail such as the Sierra Game-King. Simply put, flat based bullets are a configuration more easy to fabricate with a high level of accuracy. As the majority of my rifles are for hunting applications, I use plain ol' Hornady Interlock SP's....

FWIW - Your groups look pretty good to me. When you get down to this level of repeatability, the skills of the operator are often controlling the results. Those skills can vary from day-to-day....

 

[doowroh]

Have you tried adjusting your OAL? How far off the lands is the bullet. I have found a few rifles over the years where this tightened the groups quite a bit. Some have more free Bore. Be cautious as you increase your OAL as it will effect pressures.

I was wondering the same thing. Your OAL looks kinda short.

I suggest the bullet 20 thou off the rifling, to start.

I agree that my OAL of 2.750" looks short on paper. I'm using the #2140 GameKing, and well, it's got "hips", if you will. 2.750" is the specified OAL in both the Sierra 5th and 6th editions.
I actually find that if I set the seating depth any further out, the rifling pushes the bullet back into the case (no crimp) to an OAL of +/- 2.750".

So seeing the you recommend 0.020" off the lands, and if my redneck math tells me that my rifling is where it is, should I be seating to +/- 2.730"? That's looking even shorter than it did before? LOL.
I'm happy to have you advice, because I really don't know what to try next.

 

[remington jim]

My Ruger Scout likes my 45 grs Varget with a Horn 165 SST bullet too ! RJ

 

[blargon]

I always had better luck with IMR4895 and 165gr bullets.

 

[BioPace]

I agree that my OAL of 2.750" looks short on paper. I'm using the #2140 GameKing, and well, it's got "hips", if you will. 2.750" is the specified OAL in both the Sierra 5th and 6th editions.
I actually find that if I set the seating depth any further out, the rifling pushes the bullet back into the case (no crimp) to an OAL of +/- 2.750".

So seeing the you recommend 0.020" off the lands, and if my redneck math tells me that my rifling is where it is, should I be seating to +/- 2.730"? That's looking even shorter than it did before? LOL.
I'm happy to have you advice, because I really don't know what to try next.

Get a tool that measures to the ogive if you think that's an issue. COAL is not as useful.

https://www.hornady.com/reloading/p...s-and-gauges/lock-n-load-bullet-comparator#!/

 

[444shooter]

Have you tried the 155gr Sierra?

 

[doowroh]

Get a tool that measures to the ogive if you think that's an issue. COAL is not as useful.

https://www.hornady.com/reloading/p...s-and-gauges/lock-n-load-bullet-comparator#!/

I have both the bullet comparator and the headspace comparator tools from Hornady. I use them for setting my seating depths and for measuring/deconstructing factory ammo.

Bullets are Sierra #2140 165 grain HPBT.
OAL is 2.750" and CBTO (if that matters) is 2.257" (+/- 0.003").

I was wondering the same thing. Your OAL looks kinda short.

My response/question about the OAL was directly in response to Ganderite's comment, presumably based on my first post about my OAL being set to 2.750", and looking low.

Have you tried the 155gr Sierra?

No, I actually have not. I have been trying to avoid getting lost in the data by keeping things simple. I'm trying to at least. For me at least, I've got 4 different powders, a couple of different bullets (weight, manufacturer & design) and honestly, not enough time at the range to test that many variables, while keeping things true to some semblance of the scientific method.

You specifically mentioned the 155gr, of which there appears to be 3 available bullets. Do you have experience with, or are you suggesting the SMK, SMK Palma or the TMK?

Much appreciated.

 

[Canuck71]

You mentioned that this was your first time shooting prone, and your back and neck did not like it. A couple of years ago I took a course and shot prone for the first time. In less than 5 shots my neck was cramping up and killing me. The instructor folded up my bipod and lowered the muzzle of my rifle 3”. Problem solved! My 6-9 inch bipod was replaced with a 3-6 inch model that another shooter was kind enough to lend me and I shot around 200 rounds over a day and a half with no issues at all. If you are shooting off a bipod try lowering it, and hopefully you will see the pain go away too.