Stuck on caliber decision - input appreciated

[MudRunner2005]

A 6.5 or 277 will NEVER equal a 7mm for killing power or LRH. You can play with the numbers all you want but a 280 Sherman spitting a 175 ELD-X at 3k will slaughter any other choice. A 6.5-06AI is a fun rig and I have had a few as predator/deer rigs. For a deer/larger rig the 7mm bore is light years ahead of the smaller stuff. The 270 would be better but it is still hamstrung by bullet selection, if your build doesn't like the 170EOL WHAT NOW?
Recoil? BRAKE!
Both of your smaller choices are NEAT rounds but practically, a 7mm will walk away from them in nearly every category especially in killing power.

Except for if you're talking about a .280 Sherman pushing a Berger 180 Hybrid at 3K...

 

[Creedmoor shooter]

Except for if you're talking about a .280 Sherman pushing a Berger 180 Hybrid at 3K...

Heck the bc on the 162 eld-m isnt far off from the 180 berger. The 180 eld-m is rumoured to have a .712

 

[bigngreen]

You'll pay an increasing price in recoil as you go up the cals, I shoot them all and have no real one that sticks out over all, I've dumped many elk beyond 800 yards with 6.5's, some of my longest kills on elk are with 270's, we taco them with big 300's and 338's so I find it real hard to blanket statement one better than another. Interestingly I built the one and only 7mm any of our crew shoots, all have dropped 7mm's for 6.5 or 270's or 338's.
Rich will have a 338 Sherman soon too set up with a 250 Berger that should be an awesome set up as well. So many ways to skin it but I would definitely give mag length a serious consideration cause it's a big factor.

 

[geocodyrgia]

OhioHunter - My worry was that without the additional boiler room of the Sherman, even the 180's would be a stretch to make 2800 fps with a 26-ish" barrel. It seemed that most of the 284/280ai guys stuck to the 168gr bullets for velocity as the velocity made up the BC difference between it and the 180's. With the Sherman I was hoping to get the best of both.....although aren't we all?

Any real world experience to correct my understanding if I'm off is greatly appreciated!

-Chad

 

[elkaholic]

ToddC, you've summed up my quandary and general thoughts perfectly.

I like the idea of the 6.5-06 but it seems to overlap a lot with my 25-06 (although there's a good chance the 25-06 becomes a 6.5-06 when the barrels gone sometime down the road). Right now I guess I consider the Ruger tang safety 25-06 (inherited feom wifes grandfather) my "primary" hunting gun with 120 Game Kings moving somewhere near 3200 fps for use on deer and hogs. That allows this project to concentrate a bit more on fun/range

And you're dead on with my fears about the venerable 270. I love the round and will gladly pick up or inherit one, but given the chance to build, it's hard to go that route with the lack of heavy bullet options. Even finding 8-twist barrels in 277 was a bit of a limiting factor. They're out there but you had to look.

OhioHunter, I've also looked quite a bit at doing this based on the 284 Shehane as you mentioned. I'm interested to hear your experiences with the heavy 7mm bullets not fitting a Savage internal mag with an '06 case. It was something id thought about but didn't think would be a problem, but I'm man enough to admit I could easily be wrong. Your experience is greatly appreciated.

Rich, if I remember correctly the first Sherman cartridge was the 6.5, correct? I'm very interested to hear some of your thoughts for that backstory as I think it would be very relevant here. I'm guessing a good bit has to do with your comment below. Particularly as I'm trying to move the heaviest bullets I can with an '06 case at reasonable speed, your practical experiences with building the Sherman rounds and the thoughts youve come away with from the numbers you've run would be hugely appreciated!

First of all, you would have an issue in the Savage with the Sherman coal. You would need 3.5" range for most of the Sherman long action rounds.
The first Sherman WAS a 6.5 and was built after killing some 25 bull elk with an A.I. in 6.5. After burning out the 2nd barrel, I decided to build a Gibbs to get even more oomph. By taking one look at the case and finding the neck looked like Shreks, NONE, I decided to build my own design. The Sherman is a combination of the two which includes the best of both; the capacity of the Gibbs with a lot of Ackleys case design with less body taper. The result was an operating range of 3200' with the 140's and 3000 with 160's.
I will use the 300 Sherman as a comparison because I am familiar with them. You could make the same comparison between the 6.5 and 300 WM if you want. Here is some data using top useable velocity in both. I will use the 143 eldx compared to the 212 eldx. The 212 has a little edge in b.c. so it will be favored a little in comparison.

1000 yard data
6.5 mv=3200 19.8 moa @1000 4.5 moa Wind@10mph 1941 vel.@1000 1196 lbs.
300 mv=2950 23.6 moa @1000 4.9 moa wind@10mph 1782 vel@1000 1495 lbs.

As you can see, the 6.5 shines in every area except ft. lbs. and the frontal area of the 300 bullet is also some advantage.
As a side note, you can run the 215 Berger at 2950 and gain some of the advantage back to the 300.
Hope this helps!........Rich

As Rhian mentioned, if it's a hammer you like, the 338 at over 2800 with a 250 Berger should really open some eyes!
Untested, but pretty sure of velocity.

 

[MudRunner2005]

Heck the bc on the 162 eld-m isnt far off from the 180 berger. The 180 eld-m is rumoured to have a .712

Have the Hornady BC's been proven by Litz yet? Not that I doubt Hornady, but many companies have been known to inflate numbers...Either on purpose, or from old testing equipment that is not as accurate as it could be. I trust Bryan's test numbers more than the manufacturers. I trust Berger's numbers because Bryan is the one who determines their numbers.

 

[Creedmoor shooter]

Have the Hornady BC's been proven by Litz yet? Not that I doubt Hornady, but many companies have been known to inflate numbers...Either on purpose, or from old testing equipment that is not as accurate as it could be. I trust Bryan's test numbers more than the manufacturers. I trust Berger's numbers because Bryan is the one who determines their numbers.

I think i heard that he did test them but I haven't seen anything on them. Hornady lists their bc over the velocity range on they're website so I take the average from those three numbers and that's what I use and it's pretty accurate.

 

[elkaholic]

The 143's are very close out to 1300 yards in my 6.5 SS.......Rich

 

[geocodyrgia]

I figured since the conversation turned towards magazine length I'd go measure. Numbers established from putting a Berger .277 170gr into a case until it just barely cleared the front of the mag box. Numbers are approximate because it was kind of dark in the garage.

OAL length I can fit in the old Savage = 3.46

OAL length I can fit in the Ruger MKII = 3.381

Will 3.46 fit a 280 Sherman with a 180gr bullet seated so the boat tail doesn't intrude on powder space?

 

[toddc]

140M and 143X have been minute of porcupine tested out to 1400. 7mm 175X has gone minute of small rock to 1675 yds.
Paper drops at 750 and 1000 were spot on. The 140X actually was about .75 MOA high at 1k.

 

[elkaholic]

I figured since the conversation turned towards magazine length I'd go measure. Numbers established from putting a Berger .277 170gr into a case until it just barely cleared the front of the mag box. Numbers are approximate because it was kind of dark in the garage.

OAL length I can fit in the old Savage = 3.46

OAL length I can fit in the Ruger MKII = 3.381

Will 3.46 fit a 280 Sherman with a 180gr bullet seated so the boat tail doesn't intrude on powder space?

That is about the exact length that a 140 Berger coal is in the 6.5 with the std. throat (not the new longer one) but it is too short for the 180 in the 280.

 

[elkaholic]

The 280 Sherman with a 180 VLD would need around 3.525"






these 2 shots were 1 grain apart

 

[FEENIX]

For the 270 I'd go 1:8 to shoot the 170 Berger. Feenix, those are incredible speeds! Do you find a 30" barrel to be awkward if you have to carry it? Realistically I'm got other rifles that will carry well, there's no particular reason I'd have to limit the barrel length, but I'd be interested in your thoughts on if you use your rig for hunting.

At first yes (esp. going through timber) but I got used to it in no time.

 

[toddc]

Should be able to use the magnum length box in the Savage.

Savage Shooters - Staggered Feed Magazines