I keep thinking about a 7mm

[Joe R]

I’m trying to stay focused on F-TR, but I keep thinking about a 7mm. I know that the straight .284 is the current favorite, but since I’m very familiar with the .308 and I have lots of .308 brass I was thinking that a 7-08 may be a good option for me.

Additionally, I would be able to use the Lapua Palma brass so that I get all the advantages it has and I wouldn’t have to to keep two different size primers. I don’t see any reason why 44-45 grains of Varget wouldn’t be able to push a 180 grain to the 2,830 fps node. What am I missing?

Thanks,

Joe

 

[Steve Blair]

44.0 grains Varget would produce ~2840 from a 32" barrel. The problem is that pressure would be ~76 ksi.

 

[Joe R]

Hi Steve,
I'm running 44.8 grains right now, pushing a 200 grain hybrid without any problems.

 

[dkhunt14]

There is no place for a PM or email in your profile. Matt

 

[XTR]

Give it a whirl and see if it will work, but I think you will fall short of your velocity goal.

The difference in your 308 and the 7-08 is a bout 15% less area in the hole (bore) to vent the gas, and about the same bearing surface on the bullet. It is going to build pressure faster.

Since you are already planning to make the brass from Palma brass go ahead and blow it out to an AI. It'll give a little more capacity.

 

[Joe R]

Ben Steinsholt sent me a short lesson on overbore, I may have to change powder. He also advised the AI route.
Thank you all for responding, it is appreciated.

Joe

 

[XTR]

If you do this I think H4350 will be about the right spot for a powder. I tested it with the 162s and thought it was too slow. I was at compressed loads and not getting the velocity that I was looking for, and my reamer has a loong (like 180something) just for the 162s, but I think that with the 180s you'd find your max load somewhere just below 100% fill.

 

[BOB LEE SWAGGER]

I have a reamer from JGS, Brux barrel & 200 pieces of new Norma brass for a future "modified" .284. Then I started thinking (code for about to spend money) and thought why modify existing cartridges for more? I currently shoot a 6.5-.284 (another shout out to Benjamin S.) that first day shot 3 groups in the 1's & 2's at 100. I also shoot a 7SAUM that has been super easy to tune with 180 hybrids & 4831sc. Brass has been available and has held up very well. So again...We will always tinker. If we are smart we start with a couple of hammers so that we can allot more time and patience to our projects.

 

[wapiti25]

If you build the 7-08 now you can rechamber later to 284 or one of the larger cases. Bigger cases/more powder will recoil recoil more. Good luck

 

[whysman]

Hi Steve,
I'm running 44.8 grains right now, pushing a 200 grain hybrid without any problems.

Difference is that you are running that in a .308 vs a .284 The smaller bore size makes a difference

 

[gilmillan1]

your best bet would be an ackley 7-08 or a 260 ackley improved. Those two cartridges will get close to the performance of a 284, but not quite. Want my advice!? Stop waiting your time, and just get a 284! I have done it way too many times to know it is not worth it. You are simply trying to reinvent the wheel, and after you try so hard to do it, you will realize it would have been alot easier and cheaper to get a 284. But again, its your money and your time.

 

[Mulligan]

http://ozfclass.com/phpbb/viewtopic.php?f=5&t=7100&sid=e6e67d82c218504cbbdc8ec1992a3154

Check out this thread, the Mates are getting 2830 with an AI 28-30" barrel using 2209 (H4350). Yes the 308 Palma brass is cheaper then the Norma 284 and is holding up very well for them.
CW

 

[Joe R]

Guys,
I appreciate you taking the time to respond to my question.

Every time I start day dreaming of a 7mm reality catches up with me. Common problems have a common solution and for a 7mm it seems to be straight .284 .
Thanks again,


Joe

 

[bobinpa]

Guys,
I appreciate you taking the time to respond to my question.

Every time I start day dreaming of a 7mm reality catches up with me. Common problems have a common solution and for a 7mm it seems to be straight .284 .
Thanks again,


Joe

I don't want to hijack your thread, but why not a 7 WSM?

 

[Zero333]

You can go with the 7mm-08AI and it will work with 180's.

100-150fps slower than the 284w with 180's, assuming equal barrel length and pressures.. Barrel life will last longer.

 

[Mulligan]

You can go with the 7mm-08AI and it will work with 180's.

100-150fps slower than the 284w with 180's, assuming equal barrel length and pressures.. Barrel life will last longer.

Those shooting an 7-08 AI are getting 2830 with the 180's, I think that is the same as a .284 with less powder and Lapua Palma brass.

 

[johnnyi]

Guys,
I appreciate you taking the time to respond to my question.

Every time I start day dreaming of a 7mm reality catches up with me. Common problems have a common solution and for a 7mm it seems to be straight .284 .
Thanks again,


Joe

Have you ran the numbers in quickload to see what the pressures it would be? or simulate what the results would be down at the next lower node?

 

[Canadian bushman]

Guys,
I appreciate you taking the time to respond to my question.

Every time I start day dreaming of a 7mm reality catches up with me. Common problems have a common solution and for a 7mm it seems to be straight .284 .
Thanks again,


Joe

I feel the same way.
I think you outta just build one and get it out of your system.

 

[Joe R]

Have you ran the numbers in quickload to see what the pressures it would be? or simulate what the results would be down at the next lower node?

Okay Guys,
trying to hone in on whether a 7-08 can do the job as an F-Open, 1K yard rifle. Below are the QL number. I'm assuming a chamber with a 210 freebore. I've run the numbers with two powders that I am not familiar with H-414 and RL-17. I'm looking for advice regarding the powders as well other related factors that I may be overlooking.

I appreciate you taking the time to answer my queries.

Joe

 

[Canadian bushman]

My experience with the 7-08 and 168's using rl 17 makes me think 2850 with 180's will destroy the brass if it is even remotely safe to fire.

With the way rl-17 spikes in the heat. I would stray away from running anything that hot with it.

I have always considered h414 a sperical equal to h4350. Although i get great results from 4350 ive never reached the speed i did with rl-17.

I also know a few guys running the 180's and 195's outta the straight 284 with rl-17. The velocities are much more impressive and easier to ottain.