Load development for .308 F/TR

[Forrest Mc]

I am developing a load for 1000 yard FTR. I used 100 new Lapua Palma brass, Berger 185 Juggernaut Target bullets, BR-4 primers, Varget powder. I turned the necks to .14", chamferred necks in and out, ran thru expander mandrel and then loaded 37.5 gr of Varget in 50 cases and seated the Bergers, 5 each, from touching the lands down to .045" jump in .005" increments. Seating test Results:

I opted to do the charge test with the 2.205 seating depth due to the better vertical. Beginning with 39.0 gr. up to 43 gr. in .5 gr increments here are the disheartening results:

Every one of the fired cases of the "charge test" exhibited this ring at the bottom of the neck (the 50 fired in the seating test did not).

I am looking for your observations and advice.

 

[MikeMcCasland]

How much freebore on your reamer, and what were your velocities. Your charge weights seem low to me.

Edit: Barrel length would be helpful too. No idea on the ring.

 

[Kurz]

Maybe I do this backwards but I start with the load development first looking for those nodes then select the promising node and work on the seating depth.

Could that ring be from neck turning?

 

[Ned Ludd]

I personally don't make too much of the carbon ring until (or unless) it starts doing something extremely weird, if that's the ring to which your referring. Yours don't appear to be doing that. I don't turn necks for my F-TR rifles, so if you're referring to the ring cut into the brass at the neck/shoulder junction, it looks like you might have gone in a bit deep there with the tool. I suspect that won't become so visible after the first annealing cycle. Unless you're concerned it's causing some structural integrity issue, I wouldn't worry about it.

As far as the load itself, you didn't state what your COAL values, freebore length, or barrel length were. These are important values in terms of getting better feedback on the load. On the surface, I'd agree with Mike in that your charge weight is probably anywhere from one half to a full grain low, depending on your specific COAL/freebore.

My suggestion would to start with the Jugs seated at either .015" or .020" off the lands. With Palma brass, I'd run the charge weight test up to at least somewhere in the neighborhood of 43.5 gr. Although I don't know what length barrel or freebore you have, with a 30" barrel and suitable freebore, a load with 185s and Varget ought to tune in nicely with velocity somewhere in the neighborhood of 2730 to 2760 fps. Once you find that charge weight window, re-visit seating depth, testing from approximately .015" to .030" off the lands on .003" increments.

 

[Forrest Mc]

How much freebore on your reamer, and what were your velocities. Your charge weights seem low to me.

Edit: Barrel length would be helpful too. No idea on the ring.

Thanks for the reply, Mike. This is a new-to-me Savage 12 F/TR .308 with their 30" barrel. Supposedly 400 rounds thru it before I got it last week. No reamer and I read that the default factory Obermeyer reamer is .085, but the factory team chambers were .170 freebore back in 2013. That was info from a factory team member posted on another forum.

 

[Forrest Mc]

Maybe I do this backwards but I start with the load development first looking for those nodes then select the promising node and work on the seating depth.

Could that ring be from neck turning?

Kurz, I am puzzled because I turned all 100 necks to 14 thou. The 50 used for seating test did not produce a ring like all that were shot in the charge test. Seating tests were with 37.5 gr of Varget while the charge test started at 39.0 gr.
Berger responded to my email about Juggernauts and suggested starting with seating test. I used to do it "backwards", too.

 

[Forrest Mc]

I personally don't make too much of the carbon ring until (or unless) it starts doing something extremely weird, if that's the ring to which your referring. Yours don't appear to be doing that. I don't turn necks for my F-TR rifles, so if you're referring to the ring cut into the brass at the neck/shoulder junction, it looks like you might have gone in a bit deep there with the tool. I suspect that won't become so visible after the first annealing cycle. Unless you're concerned it's causing some structural integrity issue, I wouldn't worry about it.

As far as the load itself, you didn't state what your COAL values, freebore length, or barrel length were. These are important values in terms of getting better feedback on the load. On the surface, I'd agree with Mike in that your charge weight is probably anywhere from one half to a full grain low, depending on your specific COAL/freebore.

My suggestion would to start with the Jugs seated at either .015" or .020" off the lands. With Palma brass, I'd run the charge weight test up to at least somewhere in the neighborhood of 43.5 gr. Although I don't know what length barrel or freebore you have, with a 30" barrel and suitable freebore, a load with 185s and Varget ought to tune in nicely with velocity somewhere in the neighborhood of 2730 to 2760 fps. Once you find that charge weight window, re-visit seating depth, testing from approximately .015" to .030" off the lands on .003" increments.

Thanks for the reply, Ned. My bad in not mentioning that this is a Savage 12 F/TR (single shot) with their 30" barrel. I bought it slightly used with no freebore reamer. As for COAL I did not measure it, only considering CBTO. I measured distance to lands two ways; the Hornady tool with a fireformed case that I drilled and tapped with the Bergers I used for these tests AND the a fireformed and neck sized case hooked on the bolt extractor without ejector spring. That is how I came up with 2.235" touching lands. I ended up testing charge wts at .030" off the lands.

As you can see, I ended the charge test at 43 gr. The good news is no pressure signs so I will run up another batch up to 46 gr. cautiously looking for pressure signs. Promising that I got a .32 moa group at 37.5 gr of Varget in the seating test. Roger on revisiting the seating once I have a wt window.

 

[Ned Ludd]

Forrest - for what it's worth, 46 gr is way too high for a typical 185 load. I wouldn't go any higher than the low 44 gr range. With a relatively short freebore (.085") chamber in a 30" barreled rifle, I was using 43.4 gr to hit approximately 2725 fps, with the bullets seated at ~.020" off the lands. That was a ridiculously accurate load. With a longer freebore so the bullets can be seated out farther (and therefore having a greater effective case volume), you might expect to see a load tune in a little faster, perhaps to the 2740 to 2750 fps range with a 30" barrel. I'd expect you'll hit that somewhere in the mid to upper 43 gr range with Varget. I'm not even sure you could get 46 gr into the case and still seat a bullet. Regardless, that would create serious over-pressure (safety) issues, so no need to go that high.

 

[Nowhere Man]

ÀThe factory barrel is a 1/12" twist and doesn't do well with anything heavier than 168.

 

[MikeMcCasland]

Forrest,

I'd agree with everything Greg is saying; it's spot on advice. I would also suggest not jumping .5gr increments in powder charges; you're very likely skipping right over nodes. If I were you, I'd load up another batch starting at say 42.5gr, and jump in .3gr increments until you get to 44.6gr. Do that .020" off the lands.

44.6 will most likely be too hot, but just want to ensure you actually cover your 'high node'.

From there, go back and put the bullet .010" from the lands, and work it back in .003-.005" increments. You're almost guaranteed to find something that will 'bughole' them at 100 with this combo.

Edit: Just saw Nowhere Man's post, and went to Savages site to confirm. I guess they made this rifle to shoot 155s specifically? That is absolutely crazy.

 

[LVLAaron]

FYI. Brand new barrel cut with the FTR team reamer, 168 freebore is 2.308 to the lands with my batch of juggs.

Juggernaut should be fine in a 1:12 - https://bergerbullets.com/twist-rate-calculator/

FWIW: Small primer brass will serve you a lot better here.

I run 43.5 - 44.2 (varget) and that gets me to 2725-2750 on a 30 inch 1:10 barrel

I've found the juggernauts to not be picky about seating depth. Litz said something to the affect of just seat them at 12 off and dont change it through the life of the barrel. As the throat erodes, the hybrid will still perform fine. I've shot 5k juggs at this point and found this to be very true.

 

[Nowhere Man]

I was able to put around 4000 rnds of 168's through mine before it wouldn't group well. All attempts at heavier bullets didn't go well.

 

[Ned Ludd]

ÀThe factory barrel is a 1/12" twist and doesn't do well with anything heavier than 168.

Berger's suggested minimum twist rate for the 185 Juggernaut is 1:12. I know plenty of folks that have used them out of the factory Savage 12 F/TR rifle with excellent results.

 

[Nowhere Man]

What am I missing? Berger says it's marginally stable and recommends a lighter bullet, does it not?

 

[Jdne5b]

What am I missing? Berger says it's marginally stable and recommends a lighter bullet, does it not?

Probably Altitude. Whats it say at sea level vs 1000ft.

 

[Nowhere Man]

Forest,
My testing w/ 185's had similar results to what you've experienced.

 

[miningshawn]

I feel your pain....

I just had the exact same components do the exact same thing to me. The only difference was Starline brass (and CCI BR2 primers ) and I only neck turn until "even neck" and try to keep neck tension exact for each round (typically 0.003).

The 185 Juggernauts refused to work for me until I reached 2500fps, which only happened after 44gr of Varget - again in a Starline case. The final step was seating 0.005 INTO the lands. All results when pulling away from the lands were frustratingly inconsistent for me. Final load:
Berger 185 OTM
Starline brass
CCI BR2
44.5gr Varget
neck tension 0.003
seated to ogive using Hornady Bullet Comparator
Measured to lands using Hornady OAL Gauge

Shooting in a box-stock RPR Gen2. 0.27MOA from front and rear bags. The only magazine I own which will feed these is an Alpha Industries mag which is sadly not offered any longer.

Good Luck!

 

[savageshooter86]

You will chase your tail with the factory barrel. Trust me. Get a criterion pre fit barrel. Have it throated out some. And your headache of getting tight groups will go away

 

[Forrest Mc]

Alright, I'll refine the seating to .003" increments from 2.225 back to 2.205
Then with the most promising (with emphasis on least vertical) do charge tests start at 42.5 and work up to 44.6 in .3 gr increments.
I started with the 185 Juggernaut Target #30418 having faith that Berger knows their business. It is confusing, tho, that the Juggernaut Target, Juggernaut OTM, and BT Long Range are said to be the same bullet, yet the SG value differs.

 

[Ned Ludd]

Alright, I'll refine the seating to .003" increments from 2.225 back to 2.205
Then with the most promising (with emphasis on least vertical) do charge tests start at 42.5 and work up to 44.6 in .3 gr increments.
I started with the 185 Juggernaut Target #30418 having faith that Berger knows their business. It is confusing, tho, that the Juggernaut Target, Juggernaut OTM, and BT Long Range are said to be the same bullet, yet the SG value differs.

The differences between Juggernaut and the 185 OTM are essentially Lot-to-Lot variations. I've used plenty of both. Similar dimensional variance can be found between different individual Lots of either bullet, which might have a very small effect on Sg under given velocity, twist rate, and atmospheric conditions. The BT Long range is simply different terminology for the 185 Juggernaut, it's the exact same bullet.

A 12-twist is plenty for the Juggernaut. According to Berger's Twist Rate Calculator, at 59 degrees F and 0 ft elevation, pushing the Juggernauts at 2750 fps out of a 12-twist barrel will generate an Sg of 1.43, a estimated compromise of 2% of the intrinsic BC. This is their "worst-case scenario" and I suppose if you do a lot of shooting on the beach in November through January, it might be a small consideration. At 65 degrees and 1000 ft elevation, the estimated Sg goes up to 1.50, which is good for the full BC value.

For comparative purposes, I run the 200.20X bullet at ~2650 fps out of a 30" 11-twist barrel. At 65 degrees F and 1000 ft elevation, the twist rate calculator estimates an Sg of only 1.35, which translates to a 4% decrease of the intrinsic BC value - a much larger decrease than when running a Juggernaut out of a 12-twist barrel. I can assure you the 200.20Xs shoot just fine out of an 11-twist barrel.

None of this is any guarantee that the Jugs will shoot lights out from any particular rifle. It merely suggests that if they do not shoot well, the problem is likely something other than twist rate. The Jug is usually a very forgiving bullet and easy to tune, but I can easily imagine that not every single rifle is going to be a laser with them. As has been noted by others, borescope images of Savage factory barrels are generally not very flattering, even though most of the ones I've seen shot very well out of the box. I'd be far more concerned if the Jugs couldn't be easily tuned in with a quality replacement barrel, although if you're going to put a new pipe on a commercial rifle for use in F-TR, you might as well buy one with a more appropriate twist rate (i.e. 10-twist) and load up the 200.20X or 200 Hybrid bullets.

If you want to get your money's worth out of the factory barrel and the Jugs simply don't work out for one reason or another, another option would be the 168 Hybrid. There is a very nice node at ~2900 fps from a 30" barrel with H4895. In my hands, they like to be seated at ~.012" to .015" off the lands. The BC of the 168 Hybrid is very high relative to its weight and at 2900 fps, the predicted performance is close enough to that of a Juggernaut at ~2750 fps that the difference isn't work talking about. At any rate, it's another option that is compatible with a 12-twist barrel.


59 degrees, 0 ft. elevation


65 degrees, 1000 ft. elevation