NEW! Berger 308 bullet with wicked 0.328 G7 BC!

[Ned Ludd]

Bryan, thanks for your response and clarification. I figured it might have something to do with the contact/measurement point because some of the bullet figures in your book actually show that measurement point well in front of the bearing surface/ogive junction. In the edition I have, the 200 Hybrid is not pictured that way, so trying to compare those measurements directly to the ones you provided for the 200.2X above may be somewhat "apples to oranges". No matter. The main reason I was asking is I have a recently re-barreled .308 with a 30" 11-twist barrel. I had a new reamer made by Dave Kiff for this rifle with .180 freebore and have been shooting the 185 Hybrids. IMO, that freebore is perhaps a little longer than necessary for that bullet, but they shoot just fine. A number of high-level F-TR shooters have successfully used 11-twist barrels with the 200 Hybrids, even though it's not an optimal twist rate. Based on your original info and latest response, I'm thinking the 200.20X ought to load up just fine in that chamber, so I'll give them a try. I can make a QL file for the 200.20X with the information you originally provided to aid in load development. Thanks.

 

[STOMP442]

What powders are you guys finding that are working the best for the 200 class bullets in the .308? I am debating building a .308 but only the heavy high BC bullets interest me.

 

[JasonT]

I really like Reloder-17 for heavy bullets 185gr+. It's got a very flat pressure curve compared to Varget and 4064. RL17 is also a very interesting powder that seems to modulate its own burn-rate to work with lighter and heavier bullets. I can't explain it, but it always shows the widest range of velocities within the 100% burn zone (when all the powder is burned) on Quickload. The only catch is that the kernels are a little big - so metering to 0.05gr is not really possible.

I've heard of people using Winchester 760/H414 with good luck. The packing efficiency of those is good since they're ball powders. There's also 4350, Ramshot Hunter/Big Game (I think), and the IMR 4451 powders that fall within the same burn rate.

 

[skiutah02]

For the adventurous, received notification from Midway that these are available.....Get a good load and load 200 in time for Nationals, anyone......?. Drew

 

[STOMP442]

I really like Reloder-17 for heavy bullets 185gr+. It's got a very flat pressure curve compared to Varget and 4064. RL17 is also a very interesting powder that seems to modulate its own burn-rate to work with lighter and heavier bullets. I can't explain it, but it always shows the widest range of velocities within the 100% burn zone (when all the powder is burned) on Quickload. The only catch is that the kernels are a little big - so metering to 0.05gr is not really possible.

I've heard of people using Winchester 760/H414 with good luck. The packing efficiency of those is good since they're ball powders. There's also 4350, Ramshot Hunter/Big Game (I think), and the IMR 4451 powders that fall within the same burn rate.

Thank you for the info. I was leaning toward R17 anyways as I have a bit to spare.

 

[Ned Ludd]

Thank you for the info. I was leaning toward R17 anyways as I have a bit to spare.

Be careful when developing your load if you shoot where there is a tendency to warm up quite a bit during the day. Excess pressure and R17 go hand-in-hand on hot days with longs strings of fire.

 

[JasonT]

Be careful when developing your load if you shoot where there is a tendency to warm up quite a bit during the day. Excess pressure and R17 go hand-in-hand on hot days with longs strings of fire.

You're right - there is a mild temperature sensitivity associated with RL17. That's why I keep my maximum loads at or below 59,000psi on Quickload. Gives me a few thousand psi to "play with."

 

[Quickoz]

What sorta pressures are needed to get 2600fps with 200 Hybrids and 308? Whats barrel life like? I plan on getting a 308 10T in the new year for a backup F-Open and also F-TR barrel.

 

[Auto-X Fil]

If you load to 3.000" OAL, and use RL17 or H414, 2600fps is a moderate load in a 30" barrel. 58kpsi or so per QL, assuming Lapua brass with 54gr H20 capacity.

CFE223, 4895, and RL16 all deserve consideration as well.

 

[memilanuk]

What powders are you guys finding that are working the best for the 200 class bullets in the .308?

Varget or H4895 will get you there.

 

[Quickoz]

What about H4350? H4895 and Varget are easy to get down here but the RL powders aren't anymore.

 

[memilanuk]

Little bit on the slow side. Varget and H4895 will get you to the 2600-2650 sweet spot for a 200 hybrid in a 28-30" barrel, right around 2700 in a 32". The slower powder might get you to the next node up, or it might not. With a .170 freebore, Varget and H4895 both work in a *lot* of guns.

 

[swadiver]

ok, i will try again. i got a Criterion barrel with about a .105 freebore. the 185 Juggs shoot very good. is this enough free bore for these new 200.20x?

 

[whatwind?]

I'm most familiar with 28" barrels and we're getting~2600-2625 fps, I think you'll be closer to 2650-2675 in a 30"/32" barrel. They're typically faster than the standard 200 Hybrid at the same pressure but I hesitate to put a number on it.

There's plenty of bullet seated in the case neck when seated close to the riflings in a .170" freebore chamber.

Low form factor = low drag = higher BC.

Dimensional data

OAL 1.508

BT Length 0.227

Nose 0.848

BTO 0.706

BS 0.413

SD 0.301

G1 BC 0.640

G7 BC 0.328

Min twist 11.5

Recommended twist 10.3

-Bryan

Pointing the bullets results yet??

 

[skiutah02]

Oooooohhh...aaaaaahhhhh....mmmmmmm

I can say that in my rifle in a barrel cut with the 2013 FTR reamer and with 1984 rounds through it, they measure 2.371 CBTO with a hard jam. For reference, the 200 hybrid is 2.373 and the 185 Jugg is 2.391 in same barrel at moment. I personally would NOT use more freebore in a reamer as the bullet is out there quite a ways (a 0.015 jump will help) with a decent amount of bearing surface in the case neck, but not a ton. Drew

 

[Ned Ludd]

ok, i will try again. i got a Criterion barrel with about a .105 freebore. the 185 Juggs shoot very good. is this enough free bore for these new 200.20x?

I have a couple .308 GAP rifles I use in F-TR. I had these rifles re-barreled with 30" pipes before I ever started reloading, and had two cut for each rifle. I bought a reamer from PTG identical to the one used by GAP to cut the original chambers, which has 0.085 freebore. With this freebore, I can absolutely load a 185 Juggernaut seated at .015" to .020" off the lands and still keep the boattail/bearing surface junction above the neck/shoulder junction. However, I have found that this setup tends to hit max pressure much faster than one with more effective case volume (i.e. longer freebore, so that the bullet shank isn't sunk so far down in the neck, thereby taking up more case volume). With a freebore of .020" longer than mine, and the 200.20X that has a BTO dimension approximately .015" longer than a Juggernaut (.706" versus .691", both measured to ogive using the rifling contact method mentioned above by Bryan), you're likely to be in a very similar situation.

That does not at all mean you couldn't load them up in your chamber. It does mean you're going to hit the upper pressure boundary faster than you would with a longer freebore. It also likely means that you're not going to be able to generate quite as much velocity without going over-pressure as you could with longer freebore. However, if you hit the desired accuracy node before that, it might not matter all that much. It mainly becomes a problem when you can't hit the node without jacking the pressure way up. Take a look at Drew's measurements in the post above with the 200.20X, 200 Hybrid, and Juggernaut for comparison. Those should give you a better idea of how those bullets realistically compare in terms of seated length. Based on Drew's numbers, I would be tempted think that a freebore of .140" to .150" ought to be plenty for any of those bullets. That is actually a bit shorter than most people are typically using (~.170" fb).

Another important consideration in your situation is that if you use Lapua Palma brass, you will be getting approximately 0.4 grain more case volume as compared to standard .308 brass. Case volume is case volume, whether it comes from using different brass, or having a chamber cut with longer freebore. Greater case volume allows you to achieve the same velocity at slightly lower pressure from a given barrel length. In addition, Palma brass can take slightly higher pressure for longer than standard brass. So it may be that even with your slightly sub-optimal freebore length for the 200.20X bullet, you could use Palma brass and shoot them with no issues whatsoever. My guess is that you're close enough to the margin that the only way to know for sure would be to buy a box, load them up, and see what kind of velocity and precision you can get.

 

[Ned Ludd]

...I personally would NOT use more freebore in a reamer as the bullet is out there quite a ways (a 0.015 jump will help) with a decent amount of bearing surface in the case neck, but not a ton. Drew

About how far down in the neck is the boattail/bearing surface junction? Is it half? Less than half? I'm asking because I have a .180 freebore cut on the rifle I for which was thinking of loading these. In my current 185 Hybrid load for that rifle, the bullets are definitely seated pretty far out, maybe halfway, but it doesn't seem to be an issue and they shoot very well. As you suggested, I wouldn't want them to be much farther out, though.

 

[skiutah02]

Greg you're making it hard to sneak out to the range and shoot this thing....

My rifle likes a lot of neck tension, so you can see the bulge (I hope). The bearing surface/BT junction contacts less than 50% of the case neck but probably not 1/3. Guesstimate 40%.

(May have bumped the 185Jug loose bullet in first pic too low)
Drew

 

[swadiver]

thanks to all for the responses on the question of free bore. i am just going be forced to buy a box and give them a go. what a shame.

 

[Ned Ludd]

Thanks Drew! That 200.20X is pretty far out there. I agree with your assessment of not wanting to go out any further. Just hope they don't want to be jammed .