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What 6mm for a new build?

pa_shooter

Private
Minuteman
Mar 8, 2008
4
0
51
PA
Can't decide on a 6mm for my new build. I want to shoot the 115 DTACS. I'm looking at .243 win, 6XC, 6x47 Lapua, 6mm Rem, 6mm Crusader. This will be built on the KMW Sentinel stock and Surgeon action. I want to push them fast, but I need reliable feeding from the AICS mags, decent barrel life, good brass selection and great accuracy. Which one has the edge?
 
Re: What 6mm for a new build?

My personal choices would be either the 6x47lap or .243AI. I have the latter and couldnt be happier with it. I too shoot the 115Dtac's

The 6XC would be my third choice.. From what Ive heard its supposed to be laser accurate.
 
Re: What 6mm for a new build?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Windrift</div><div class="ubbcode-body">I want to shoot the 115 DTACS. I'm looking at .243 win, 6XC, 6x47 Lapua, 6mm Rem, 6mm Crusader. I want to push them fast, but I need reliable feeding from the AICS mags, decent barrel life, good brass selection and great accuracy. Which one has the edge?</div></div>

243 is the best.

Known performance with the 115s. (6.5mil to 1K)
Brass is good and inexpensive, plus readily available.
Hunting rounds can be easily found
Barrel life is good (3K rounds not uncommon)
Feeds from AICS mags.
Accuracy is easily .25 moa

6XC

Brass and dies from one source.
Brass is expensive
Brass has been known to be backordered frequently
Hand Loads only (or custom purchased)
Rarely can match 243 ballistics.

6x47 Lapua

Brass is expensive
Hand Load only (Lapua imports or custom)
Brass may be hard to find.
May match 243 ballistics but with higher pressure.
Barrel life may be the same as 243

6mm Remington.

Don't know about this cartridge

6mm Crusader

Fireformed Brass (right now)
Load hasn't been perfected
Barrel burner
Exceeds 243 ballistics
One source for chambering
Barrel life may be shorter than the 243
Second to the 243.
 
Re: What 6mm for a new build?

Take a look at the 6CM. Pushes a DTAC 115 very fast(I've got over 3200fps) and longer barrel life because you use H1000. I have two of them and wouldn't trade them for any other 6mm design. Another plus is that it's designed to use regular 243 win brass and fire forming is almost too easy. Just my two cents, DATP
 
Re: What 6mm for a new build?

For 115's I'd probably say .243 for ease of everything. I run 105's out of my 6x47L and wouldn't trade it for any of those. I also think barrel life will be better, but not enough to matter.
 
Re: What 6mm for a new build?

The 6mm rem looked like a good choice, but I can't find much info about anyone using it with the 115's. I know the crusader is based off of its case. Is the .243 more popular because it is better known, or are there other reasons (feeding, brass issues)? Does it's slightly larger case prevent seating the 115's out far enough?
 
Re: What 6mm for a new build?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Mike</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Windrift</div><div class="ubbcode-body">I want to shoot the 115 DTACS. I'm looking at .243 win, 6XC, 6x47 Lapua, 6mm Rem, 6mm Crusader. I want to push them fast, but I need reliable feeding from the AICS mags, decent barrel life, good brass selection and great accuracy. Which one has the edge?</div></div>

243 is the best.

Known performance with the 115s. (6.5mil to 1K)
Brass is good and inexpensive, plus readily available.
Hunting rounds can be easily found
Barrel life is good (3K rounds not uncommon)
Feeds from AICS mags.
Accuracy is easily .25 moa

6XC

Brass and dies from one source.
Brass is expensive
Brass has been known to be backordered frequently
Hand Loads only (or custom purchased)
Rarely can match 243 ballistics.

6x47 Lapua

Brass is expensive
Hand Load only (Lapua imports or custom)
Brass may be hard to find.
May match 243 ballistics but with higher pressure.
Barrel life may be the same as 243

6mm Remington.

Don't know about this cartridge

6mm Crusader

Fireformed Brass (right now)
Load hasn't been perfected
Barrel burner
Exceeds 243 ballistics
One source for chambering
Barrel life may be shorter than the 243
Second to the 243. </div></div>

Great review Mike!

Personally, I've shot the .243 win, 6XC, and the 6x47 Lapua. If I had to build any 6mm right now, I'd start by finding the 6x47 Lapua brass and dies on the internet. If I can buy the the 6x47 Lapua brass and dies, I'd build a rifle for that. In the past, Powder Valley ( www.powdervalleyinc.com ) has had a steady supply of Lapua brass.

The 6x47 Lapua cartridge is extremely well designed. You can indeed turn this cartridge into a barrel burner, but I settled on H4350 and Reloader 17 for an everyday "dead nuts on" accuracy load. Without even trying I had an excellent accuracy load that bucked the wind and did NOT burn barrels. the best of both worlds.

If you want maximum speed using the 6x47 Lapua brass, I have load data and reamer for that as well. You will have both higher performance as well as higher pressures, but the accuracy will remain very good.

I know Forester is making great dies for the 6x47 Lapua (I own a set). I think Sierra might be doing so as well.

Otherwise, the .243, the .243AI and the 6XC are excellent choices. My second choice after the 6x47 Lapua would be one of the .243's cartridges as brass and dies are easier to get your hands on.
 
Re: What 6mm for a new build?

Just built a .243 with chamber cut to fit the 115g DTAC boran coated seated to fit the AI magazine length fit in case perfectly, this was a simple project, I used a Rem 700 receiver in an AI 1.5 stock, used 27 3/4" heavy Palma contour barrel with Holland brake [awesome], recoil similar to my Rem varmit barrel .223 that does not have a brake, 45 grains of Reloader- 25 is 2,980 fps, 45.5g. gets over 3k fps, using the boran coated bullets workeeps the barrel cleaner,