Shoulder angle, why?

[BoydAllen]

I believe that Colorado gunsmith Dan Dowling is credited with being the originator of the Dasher. Why not ask him why he used a 40 degree shoulder?

 

[JRS]

It was actually Dan and Al Ashton. The design was the 22 Dasher. They wanted to achieve 22-250 ballistics from the BR case, thus, the 40 degree shoulder.

 

[NC/Br Shooter]

It was actually Dan and Al Ashton. The design was the 22 Dasher. They wanted to achieve 22-250 ballistics from the BR case, thus, the 40 degree shoulder.

So the 22dasher was before the 6dasher?

 

[CJ6]

So the 22dasher was before the 6dasher?

Yes.

 

[Dusty Stevens]

So the 22dasher was before the 6dasher?

Sadly our friend JRS has decided not to show up here for quite a few years.

 

[mikecr]

Sorry, but recoil is not affected by the case shape or shoulder angle. You cannot "displace" recoil in all dirrections.
Recoil is the sum of the weight of the ejecta times the mean adjusted velocities, divided by the weight of the rifle.
... there is nothing else involved.

Ejecta includes unburned powder.
A case design that holds more powder back in the chamber, instead of aiding the formation and release of a powder slug (adding to bullet mass), does reduce recoil.
It reduces muzzle pressure.
And it should be easier to manage a consistent pressure curve while powder is burning in one place, rather than various distances down a bore.

This comes into play more & more with larger cartridge capacities.

 

[Ackman]

It`s a BRX.....

Close, but no. Dasher is 40deg with a blown out shoulder. BRX is same 6BR 30deg shoulder blown forward, same body taper, very slightly less volume than Dasher and essentially the same velocity. 6BR dies work.

 

[Bill K]

@1 reason is that is what the dasher was in specs. #2, less trimming of the case and #3, less wear on the throat/lead area of the barrel.

 

[Will Henry]

The theory exists that, if the angle of the shoulder converges within the neck, throat erosion will be reduced. I have seen no evidence to support or refute this. I have seen evidence that case growth does not occur from firing; unless there is something about the rifle which makes it happen (headspace, action stretch, crooked bolt face, etc.) Case growth occurs during FL sizing. However, the sharper shoulder may help a bit in this regard.
The reduction of bolt thrust is a bit of a fairy tale as well. WH

 

[JEFFPPC]

2014?

 

[17VLD]

So the 22dasher was before the 6dasher?

It was actually Dan and Al Ashton. The design was the 22 Dasher. They wanted to achieve 22-250 ballistics from the BR case, thus, the 40 degree shoulder.

Al was a pd shooter in Colorado who in fact got the ball rolling in 22 caliber with Dan, later Richard Schatz asked Dan about making him a Dasher in 6mm twisted fast.
A lot of records have been set by Richard and the 6Dasher and as my Dad used to say “it couldn’t happen to a nicer fella”
The 6 BRA is also a 40* shoulder and it is no slouch either.Perhaps Mr Ackley was onto something The BR case and all it’s offspring are in my opinion the basis for some fantastic shooting be it vermin or targets.
Matt

 

[TAJ45]

40 shoulder is a bit easier on the throat.... .....no?

Significantly

 

[Alex Wheeler]

The theory exists that, if the angle of the shoulder converges within the neck, throat erosion will be reduced. I have seen no evidence to support or refute this. I have seen evidence that case growth does not occur from firing; unless there is something about the rifle which makes it happen (headspace, action stretch, crooked bolt face, etc.) Case growth occurs during FL sizing. However, the sharper shoulder may help a bit in this regard.
The reduction of bolt thrust is a bit of a fairy tale as well. WH

There may be something to that. When we started using the 6BRA vs the Dasher we noticed a very big difference in throat erosion. We are running the same velocities as the dasher only about a grain less powder with slightly higher pressures. But they are so similar the difference has to be the full length neck vs the shorter Dasher neck. I expected .001-.002 of erosion over a match weekend in the Dasher. You may not see that for 500 rounds on a BRA.

 

[6MMsteve]

It's the insomnia thread or the 3 am wow I didn't know that....... toooo much coffee