7mm Creedmoor realalistic expectations

[josh shrum]

I have been reading about the 7mm Creedmoor and 7mm GPC (Grady Precision Cartridge) and I am frankly amazed at the velocities some people are claiming to get from this cartridge.

Most of what I am finding is from last year (in terms of most recent info) and people are claiming up to 2900 FPS using RL17 and 162 Amax from this cartridge.

Can anyone with experience behind this cartridge chime in with up to date info?

Thanks!
Josh

 

[Kurz]

It's been written about here in a couple of limited threads but given it's been around since 2011, it doesn't seem to have garnered any real attraction unless it's behind closed doors.

The velocities are fairly realistic at 2900 fps in the longer barrels with Re-17 and 2750-2800 even with short 24" barrel loads. The double base, hotter burning powders supply plenty of oomph to get these velocities without exceeding reasonable pressures.

I've built three rifles, all for different reasons and clients.

One is a 24" hunting rifle which shoots the 162 gr. to 180 gr. Hunting VLDs exceptionally well. The energy is the real plus here because your range is slightly extended given the remaining energy of these loads. In an 8 lb. rifle, the recoil is very tolerable with the 162 gr. AMAX loads while the 180 gr. Hunter VLDs can get a little more insistent. But the 180 gr. loads will work for elk hunting at distances limited to your abilities with velocities running in the 2650+ fps. range.

The second was a PRS rifle built for a competitor who wanted the advantage on falling plates and such on some of the courses. This rifle showed exceptional accuracy right from the start yet had a fairly mild contour, like a #3b or #4 contributing to the lighter, overall weight. Some folks are getting tired of carrying 12 - 18 lb. rifles all day.

The third is a 32" F-Class-style rifle just to see what can be done with this cartridge. I've run some 162 gr. AMAX with decent results but I'm switching to some other types for testing later this year. The longer barrel is yielding somewhere in the mid- to high-2900's regularly at decent pressures.

No matter the opinions, this cartridge will outperform the 7mm-08. Maybe not by hundreds of feet per second but noticeable. The OAL for DBM loading is simplified with this cartridge over any of the .308 based cartridges. Now that we have the Lapua 6.5 Creedmoor brass, I think we can add this into the mix for some of the better short action cartridges.

The only argument remaining is whether to use the .30 T/C cases for necking down or the Lapua case for necking up.

Regards.

 

[josh shrum]

Thanks Kurz, I like the idea of a cartridge that can attain that kind of performance from a SA and mag length OAL.

 

[Joe R]

....The double base, hotter burning powders supply plenty of oomph to get these velocities without exceeding reasonable pressures.

Just be ready to replace the barrel after 700 rounds. Most people find that kind of barrel life to be unsustainable.

Joe

 

[Laurie]

The third is a 32" F-Class-style rifle just to see what can be done with this cartridge. I've run some 162 gr. AMAX with decent results but I'm switching to some other types for testing later this year. The longer barrel is yielding somewhere in the mid- to high-2900's regularly at decent pressures.

I can see the logic of a 7mm Creedmoor in magazine-fed SA rifles where exactly the same issues as 260 Rem vs 6.5X47L = 6.5 Creedmoor COALs to bullet and case-length ratios apply.

I cannot for the life of me see any reason to neck up the Creedmoor case to 7mm for a single shot F-Class rifle though where COAL isn't a constraint. The 7mm-08 and 7mm-08AI must always produce higher MVs simply because they have more case capacity than the Creedmoor. And brass quality issues aren't a factor either - I neck Lapua 308 Win Palma brass down to 7mm and that is no harder than necking up small primer Lapua 6.5 Creedmoor brass.

FWIW, the reason why I have a 7mm-08 F-Class rifle based on optimal COALs with 160-168gn low drag bullets for short/mid-range matches is that I want similar performance to equivalently loaded 6.5s, still with low recoil in a 22lb rifle, but crucially good barrel life too. So Viht 160 gives the 160 TMK and 162 AMax around 2,830 fps from a 31-inch barrel in a very unstressed small primer case, excellent precision and small ES values. Yes, I could stuff the case with a double-based or high-energy powder and get 100-150 fps higher MVs, but as Joe R points out why would one do so when barrel life is likely to reduce dramatically? When I want to push a 160 to 2,900 fps plus or run heavier bullets at 2,800 fps plus, I use a wonderful innovation called the 284 Win and by running it with Viht N160 or N165 depending on bullet weight get the performance I want and a very good barrel life to boot.

 

[Kurz]

The third is a 32" F-Class-style rifle just to see what can be done with this cartridge.

Please note that I stated 'F-Class-style rifle', not that I actually made it to compete in F-Class. The statement just gives the reader an idea of what the rifle looked like.

I think this quote is really my answer, nothing untoward or sinister, just plain old experimentation. It's fun and I get to learn. Whether it suits you or any other shooter is not the point at all since I have no agenda to push and I'm not selling anything. It suits my curiosity and lets me extend my experiences. He asked, I reported.

Quite frankly, I've never been enamored with the 7mm-08 or the improved version, small primers not withstanding. But I have the small primer Creedmoor cases on hand all the time so this was the choice I made, convenience.

Regards.