Re: What's the best way to deliver 180 gr Berger's?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Outerspace</div><div class="ubbcode-body">
The 180 gr Berger in 7mm seems to be really outstanding, and I see more and more people on the Hide shooting it for real. I have been looking at this for some time as the basis for my next rifle, hopefully to be completed this year.
So of course the question is what is the best way to deliver it to the longest ranges. </div></div>
I've been though this with calculations many times. I mostly shoot at a mile plus elevation where I live, mostly just target shooting at unspecified distances in very rural terrain. I like to hike though random terrain and drop off balloons as I go, then come back though and shoot them at what ever range I can detect them. It's fun, good exercise, and helps keep my skill up in my old age. I love the 180 Berger for rifles where it's appropriate. At the elevation I shoot stability is rarely a problem.
My "long range" 7mm rifles include:
A 280 AI 26 Rem 700 sporter ( rechambered from a 280 Rem).
It's good to well beyond 1000 yards ballistcally. Its about 8 lbs and can be shot comfortably offhand. It's far from the longest range and not the most accurate but very pleasant to shoot.
A 7mm Rem Mag Win 70 Laredo 26". Factory stock. Very accurate at 1000 yards but it can't shoot 180 Bergers. The SAAMI OAL of a 7mmRM is 3.34" which is what the Win 70 has for a magazine. 168 Bergers fit and shoot well.
A 7mm Rem Mag Sendero with 26" barrel. I only bought it recently but I expect it will shoot 180s well with it's 3.6" magazine. The cartridge OAL with 180 bullet shank seated to the shoulder is 3.534, just about perfect. It has 9.25 twist barrel which will be fine at a mile elevation. It might not be in cold weather at sea level. At a mile elevation it will go transonic about 1500 yards.
A 7mm STW with a 29.5" 8"twist Hart barrel Rem 700. I specifically designed it for 1 mile target shooting. It's well supersonic at a mile in any atmosphere (cold air, sea level). Where I shoot its supersonic to over 2000 yards. The 7mm STW is a long cartridge and the Rem 700 magazine is not long enough to shoot the 180 Berger comfortably. I've modified the 700 with a Wyatts CFE-9 magazine which gives plenty of room for the 180 Bergers to feed from the magazine. It's a 14 pound rifle with
its scope and I only shoot it prone, but it performs very well.
Even with the high BC bullets nearly all of it's accuracy limitation at a mile is from my ability to meaure/estimate/guess downrange wind deflection. It's also the most case capacity I'd want in a 7mm. I estimate barrel life will be (maybe) 1500 shots. I build a similar 300 Rem Ultra rifle. The 7mm STW gives better performance in all respects except delivered energy at a mile.
I've considered many other cartridges.
The 7mm WSM and SAUM really have no advantage over the 7mm Rem Mag. They need a long action to handle the 180's and once you have that you might as well use a 3.6" mag with the 7mm Rem Mag.
The 7mm Dakota is attractive, but has expensive and somewhat proprietary components. The 7mm SIN is similar to the 7mm Dakota. If dies and reamers become available it could be a good choice. It's just a Rem Ultra case shortened to 2.5". Both can shoot the 180 Bergers fed from a 3.6" magazine.
7mm Rem Ultra is the same length as the 7mm STW but has 112 grains case capacity! I think its way too much for a practical 7mm cartridge. Remington thinks highly enough of the 7mm Rem Ultra that they've discontinued it. I have a barrel, brass, and dies but I'll probably never assemble it. Maybe just as a curiosity.
So my vote is for a 7mm STW if you give it an action with sufficient magazine space to handle the loaded cartridge and of course the correct throat. I make it a rule not to set bullets with their shank-boattail junction inside the neck shoulder junction of a cartridge. So in my opinion the minimum cartridge OAL for a 7mm STW shooting 180 Bergers is 3.877" The SAAMI spec COAL for the 7mm STW is only 3.650". The 7mm STW has a nominal case capacity of 97 Grains. With the longer seating depth it has 89.8 grains combustion volume. A 7mm Rem Mag at 3.6" with the 180 Bergers has 75 grains combustion volume.
In my opinion if you want practical shooting with reasonable barrel life much over a mile you need to go to 338 caliber VLDs or larger and burn a lot more powder behind them.
