30-284?

[7mmrowland]

Any experiance with this round? velocity? bullet weights? barrel lenght? Please no recomending of a boring 308 or an outdated 30 cal. 1906! Traded some bullets for new lapua brass and got some dies on sale and have a 284 reamer and a 30-47 lapua reamer to do a chamber so only need a barrel.

[bsl135]

I've always thought the 30-284 would be a good chambering;

But...

What bullets will you shoot in it?

Let me know if you find something in .30 caliber that you think will out perform the excellent line up of heavy, high BC 7mm bullets (Berger and JLK 168 and 180 VLDs, 168 and 175 SMK, 162 Amax).

-Bryan

[Michael Eichele]

I have concidered toying with this very thing. It would be a step up from the 308 but sub magnum for moderate recoil, good barrel life etc....

I was thinking of running the 208 AMAX and the 177 GS bullets. I am getting up to 2550 out of the 208 AMAX in my 308 (2500 for accuracy). Using the bigger 284 case and subsequently gaining velocity over the 308, this would give the straight 284 a solid run for its money using any 7mm bullet. If I could get the 177 GS bullets flying good, it could really be interesting. Recoil would still be a bit stouter than the 284 but would also deliver more energy on the other end as well. With the added burn area of the 30 cal bore over the 284 bore, you will get near the same velocity with the 30 cal 208 as the 284 cal 180.

[bsl135]

you will get near the same velocity with the 30 cal 208 as the 284 cal 180.

But the BC of the 7mm bullet is higher. If MV is equal in both cases, the performance favors the higher BC bullet (except for KE at close range).

If there were a .30 caliber bullet ~230 grains shaped like a 7mm 180 VLD, it would have an edge over the 7mm. But there isn't (yet)

-Bryan

[Michael Eichele]

With all due respect the BC's of both bullets (published) is very close. .648 for the 208 and .659 for the 180.

If you run the numbers the energy of the 208 is higher well past 1K versus the 180 which is way beyond the realistic hunting ranges for either at these velocities. I have also shot the 208 finding a better BC than published. Near .670. I cannot vouch for the 180 VLD as I have not shot it so I am going with this theory based on the known mathematical variables.

No flame meant here. Just going with what would suit me in this situation.

To be perfectly honest, each one has their good qualities in their own right. Some of those qualities are in the external portion and some are underlaying. Neither will blow the other out of the water and niether will make the other obsolete unless you dont want to mess with a wild cat.

[bsl135]

Michael,
No offense taken.

Here are the BC's I've measured for these two bullets:
7mm 180 VLD: G7 BC = .337 (G1 BC = .659)
.30 cal 208 Amax: G7 BC = .324 (G1 BC = .633)

Your observations indicate a slightly higher BC for the 208 Amax than the 7mm 180 VLD. Without getting into a debate, let's just say for now that the two bullets probably have similar BC's.

Assuming 2800 fps at the muzzle for both bullets, the 7mm would generate 3130 ft-lb, and the 208 would generate 3617 ft-lb. A clear advantage in favor of the .30 cal.

According to my measured BC's, at 1000 yards, the 7mm retains 1586 fps and 1004 ft-lb. The .30 cal retains 1544 fps and 1100 ft-lb. So even using my BC's, you're right that the .30 cal carries more energy past 1000 yards. It's not a lot, but my hunch was that the greater velocity retention of the 7mm would result in more retained energy by ~600 yards. Thanks for pointing that out and giving me a chance to correct the analysis.

The 208 Amax is probably the best ballistic performer currently available for .30 cal. The Berger, JLK and Sierra 210's are close. The higher BC bullets are much heavier, and suffer much reduced MV.

Even using the best bullet for the caliber, the 30-284 still only reaches relative parity with the straight 284 in every category except energy, which it will have an advantage in. Barrel life will probably be better, but barrel life isn't really bad for the 284 (~2000 rounds). Recoil will be greater.

I guess what I'm saying is that from 6.5-284 to straight 284 there is a decisive advantage because the bullets are noticeably better in 7mm. However, going from straight 284 to 30-284, you don't get as big of a jump in performance because the bullets are not much better than the 7mm bullets.

-Bryan

[MontanaRifleman]

If the advertised BC of the GS 177 holds up as it appears to be I think it would leave both the 180 and 208 well behind. If the 208 can get 2800 fps, the 177 should be able to get 3200, maybe more because it is a lighter bullet and faster than other bullets for weight. In my 300 WSM I can get 2900 with the 210 Berger and close to 3200 with the 180 E-T. I would expect 3300 plus from the 177.

Using 3200/.62 for an average G1 with the 177 and 2800/.65 for the 208, 1K data shows...

208 V-1594, KE-1174, 10 MPH wind 62"
177 V-1825, KE-1309, 10 MPH wind 54"

...with of course a much flatter trajectory and bigger thump on the wallet