7 creedmoor
- Thread starter wolfman
- Start date
Surely it's been done. That said, very similar cartridges like the 7mm IMSHA and others have been around for decades.
NZ_Fclass
Silver $$ Contributor
And they were made for a specific purpose - the IHMSA is self explanatory. Theres nothing "wrong" with the 7-08, but it has been improved twice - the 7SLR, for a longer neck and the 7-08AI for increased capacity - it's good for F-Class BTW. Why you would need an underperforming 7mm....?
Thanks for that answer. What was the question?
I disagree with one exception. I will say if you can load each optimally 7-08 will always have higher velocities assuming similar brass quality. But unless you have an action/mag length that allows you to seat the bearing surface of the bullet entirely out of the case body the difference in case capacity is almost nothing. This is because making the case longer only pushes the bullet further into the case if your mag length is shorter than optimal load length. Comparing internal volume to internal volume of 6.5 creed and 260 rem from peterson for example we see 6.5 creed srp brass has 50.5 grains and 260 srp brass has 53 grains.
2.5 grains might seem like a significant number but when we look at the geometry when limited by mag lengths it makes the difference increasingly smaller as projectile weight/length increases. Nosler shows the usable capacity of each cartridge with each bullet weight in their load data. With the 140/142 bullets in each case the 260 rem only has .6 grain more capacity. The velocity/capacity gap vanishes at high bullet weights and with some powders in hodgdons load data it reverses with the 6.5 creed overtaking the 260 rem with the heaviest bullets. The 153 atip in 6.5 creed for example exceeds the average velocity of 260 remington due to this. And this effect gets worse the larger the bullet diameter gets.
7mm creed with the 180 hyb has an COAL of 2.91 with the bearing surface right at the bottom of the neck.
7mm08 with the 180 in the same spot is 3.03". To seat this to fit a 2.96 binderless mag you would lose .8 grains capacity. Where as the 7 creed would gain .7 grain and would be above any neck doughnuts. So that's 1.5 of the 2.5 grain difference back right there.
So if you are single feeding, using lighter bullets, or have an action and mag combo that allows optimal loading the 7mm08 will beat the 7 creed.
If you want to use heavy bullets and you are limited by mag length the 7mm creed would very likely match or exceed the 7mm08 with the added bonus of avoiding potential doughnut problems.
Now 7mm creed AI...
B23
Gold $$ Contributor
Then enter a 284 to the conversation and I think the 284 overshadows anything off of the 308 case or a 7 Creedmoor, even AI'd. Even loaded to short action mag length of 2.800 OAL and using a 180 Berger Hyb. a 284 has substantially more useable case capacity than any of those others.
You weren’t actually expecting germane answers, were ya?
B23
Gold $$ Contributor
I don't disagree with you on that at all. The others mentioned were all standard bolt face cartridges so I was trying to stay inline with that.
That's where us wildcatters get to play. I read your long post, and
it still boils down to the Creed case not matching the 7/08 case
in capacity in any form or function. The posting of the 284 is where
it get's to shine. With all the work done to increase case capacity
on the 7/08. I bi-passed that case completely and shortened a 284
case to be the same length as the .308 based cases. What's not to
like about a case that get's 3,2 grains more powder and fit in a short
action magazine. I'm not worried about mag capacity. A loss of one
round in a mag fed hunting rifle is meaningless. So for a 473 bolt face.
short action 7mm cartridge, my solution was to just shorten the .284
The cartridge has worked so well, I shortened it even more for BR work.
And it all started by looking at necking up the 6.5 Creed. It would have
been a waste of resources.
.284 Win.....SA284 (308 length).....284-ELF. (about 6GT length)
Attachments
They are all 35 degree like the parent case. On the SA284, I have
a node at 2820 fps using the 183 SMK with 52.2 grs of Ramshot
Hunter. It shoot's. At the last 400 yard deer match at Anderson
Creek, I won smallest group with it on an extremely windy day.
I have on hand some of the new Vhitavouri 555 for it, but have
not shot it yet.....The ELF is a work in progress. It's more at home
for 300 yards. but all my testing with it is at close UBR matches.
BR bullets are not to be found but I'm making out with the last
of the discontinued 130 SMK's. Two powders tested with the best
results are Lovex-PR (38.6 grs) and IMR-4166 (34.8 grs). These
loads get me to 2780 fps at a safe node. Really looking forward
to trying Reloder 15.5 when it comes available. Also going the
route of a solid copper bullet with the ELF. Hammer has sent me
some samples that look promising and may have them do some
custom turning for me if the math and money works out.
And Ranger.....I'm surprised Randy did'nt neck up a 6.5 Creed
just for shits and giggles. That boy is another wild catter that
knows no limit.
From what i've found, magazine capacity hasn't changed by chambering to 284 Win from 7mm-08.
It's not as drastic as going from say 7mm Rem Mag to something based on the 404 Jeffery case.
Doing a 7mm Creedmoor might make sense if your shooting from a magazine length restriction.
But your still not going to be shooting the heavy bullets from it.
Most of the guys I know are in the 2900 fps range with Berger 180's
With a standard 180 SMK I'm hard pressed to get to 2775 with my
30" Brux. That 183 Sierra although longer, has a shorter bearing
surface that lets the velocity get up there. Ramshot Hunter was the
ticket. Reloder 17 gave some excellent velocities, but groups were
poor.
I recall a fair amount of conversation on Snipers Hide with Mark at SAC working on it.
It was a while back, though.
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