Chronograph Loadings: 6mm Dasher brass, fire formed from 6mm BR Lapua Brass, with the primers noted and all results are for five shot strings:

31 gr. N140 and a Sierra 107 MatchKing (non-moly) (.020" in the lands) - 2829 mean velocity, ES 14, SD 5
(the above loading was with individually weighed charges and a CCI BR-4 primer).  This is an excellent fire forming load and is very accurate in the author's rifle.

32 gr. N140 and a Sierra 107 MatchKing (non-moly) (.020" in the lands) - 2906 mean velocity, ES 16, SD 5
(the above loading was with individually weighed charges and a CCI BR-4 primer).  This load is very accurate in the author's rifle and holds together well over long strings of fire (i.e. prone course of fire in highpower rifle 22 shots in a row)

30.8 gr. RL15 and a Sierra 107 MatchKing - moly (.025" in the lands) -  2830 mean velocity, ES 23, SD 11
 (the above loading was with thrown charges - not individually weighed and a CCI BR-4 primer)

32 gr. RL15 and a Sierra 107 MatchKing - moly (.020" in the lands)  -  2917 mean velocity, ES 19, SD 6
(the above loading was with individually weighed charges and a CCI #450 primer)

33 gr. RL15 and a Sierra 107 MatchKing - moly (.020" in the lands)  -  3000 mean velocity, ES 13, SD 6
(the above loading was with individually weighed charges and a CCI #450 primer)

33 gr. RL15 and a Berger 105 VLD - moly (.015" in the lands)  -  2996 mean velocity, ES 13, SD 5
(the above loading was with individually weighed charges and a CCI BR-4 primer)

32 gr. Varget and a Berger 105 VLD - moly (.015" in the lands)  -  2888 mean velocity, ES 12, SD 4
(the above loading was with individually weighed charges and a CCI BR-4 primer)

33 gr. Varget and a Berger 105 VLD - moly (.015" in the lands)  -  2979 mean velocity, ES 6, SD 2
(the above loading was with individually weighed charges and a CCI BR-4 primer)

The general consensus is that Varget, Reloader 15 and H4895 are three of the most popular powders of choice for the 6mm Dasher, and the CCI #450 primer is also a primer of choice for some shooters, although this author used CCI BR-4 primers and had good results with them.  This author also found VV N140 to be an excellent powder in the 6mm Dasher.

Top end loadings vary (depending on the rilfe, barrel, lot of powder, etc.) but top end accurate loadings with the 105-108 gr bullets are generally being reported in the range of 2900 - 3000 fps (with exceptions both up and down).


Chronograph Testing -  The rifle involved is a prone target rifle with a 30" Krieger 6mm 1:8 twist 4 groove barrel (.236" x .243" bore) with a 6mm Dasher chamber similar to the reamers described below on this page .

Making Brass = Very Easy!

6mm DAsher

Above: 6mm DASHER (left)

            6mm BR (right)

Base Case: 6mmBR

Modification Method: Fire Form

Shoulder: 40˚ Ackley type

Water Capacity:
Max Case Length:
Trim Length:


Dies Available.


Prints Available.


Not AR-15 Compatible

6mm Dasher

Quick Facts

The 6mm Dasher uses 6mm BR brass as the base brass.  Making the 6mm Dasher is easy and involves loading up 6mm BR brass and fire forming it in a 6mm Dasher chamber (the fire forming loads can also be very accurate).  The net result is the Dasher case that has a 40 degree Ackley type shoulder and picks up a fair amount of additional powder capacity over the 6mm BR. 

The 6mm Dasher has the capability to easily push the 105-108 gr. 6mm bullets up in the 3000 fps range.

The technique used by this author to make Dasher brass is very easy - just load up factory 6mm BR brass with a non-moly bullet using standard 6mm BR loads, using good neck tension (new out of the box brass is fine, otherwise use .004" neck tension) making sure the bullet is jammed into the lands about .025"-030", and shoot them in the 6mm Dasher chambered rifle - Done!   Not only did this author find that the fire forming loads were very accurate (using standard 6mm BR loads) but the brass, after fire forming, came out very consistent and uniform.  This author is not sure why some use the "false shoulder" method with Dasher brass (too much work and works the brass too much in this author's opinion).  The false shoulder method involves necking up 6mm BR brass with something like a .257" or .264" mandrel, then necking down a portion of the neck to 6mm again to make a "false shoulder" to hold back the case when it is chambered.  For fire forming loads, this author found with good neck tension (new out of the box brass, or .004" neck tension) and loading bullets .025" in the lands, the cases were held back fine for fire forming.

6mm DASHER

vs. 6mm BR

Ar-X/ 6mmAR.com

  LOads& Chrono

The reamer below is a No Neck Turn Design Reamer for use with the prior Lapua "Cardboard Box" brass

(For what it's worth, the newer "blue box" Lapua brass shoots well in the chamber below too in spite of its more generous neck clearance) 

Note:  The above reamer was set up specifically for the newer Lapua 6mm BR brass (known as the "Blue Box" brass) that loads out with a neck diameter of right around .2675" to .268".  This is not set up for the older "Cardboard Box" brass that typically loads out around .269" - .2695".  Since Lapua suggests that the dimension of the newer brass is here to stay a while, this .2705" "no neck turn" neck is ideal for the newer brass.

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The reamer above is a "no neck turn" reamer with Lapua's newer "blue box" brass (i.e. as of 2011).


This author likes the 6mm Dasher reamer below for the following reasons:

1.  It has an easy .2705" no neck turn neck and was set up specifically for the newer Lapua brass (also referred to by some as the "Blue Box" brass) that loads out right around .2675" - .268"
2.  It is throated well for most of the 105-108 gr bullets with the .130" freebore coupled with the 1.555" chamber length (particularly the current versions of the Berger 105 gr. VLD and the Berger 108 gr. BT.
3.  The "max chamber" length of 1.555" worked out very well with the Lapua 6mm BR brass, because when fire formed, most of the Dasher cases came out being around 1.542" in length.
4.  The dimensions of the case dovetail well with the Redding dies which size the cases adequately but not excessively.

6mm DaSher Reamers:

rcw3@erols.com  -  215-348-8789

199 North Broad Street, Doylestown, PA, 18901