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6Dasher Long Neck from 6x47L?

Been giving thought as to whether or not it would/could be worth it to do a custom Long Neck Dasher in the name of protecting the throat a little for for high volume colony/varmint shooting (plus more forgiving to shoot wider range/length of bullets). For competition I'd simply stick with with 6BRA, but with regular Dasher I'm able to push the 87 Vmax 3500 fps, though I'm concerned about barrel life with the silly short neck. I think/believe a longer neck would help protect throat and extend barrel life...though I'm not sure how much. I liked the idea of the Norma/Shiraz long neck Dasher...just don't like Norma brass. So my thought...why not form long neck Dasher brass from Lapua 6x47 brass (and of course have a reamer made up accordingly)...maybe even leave the neck EXTRA long. Could even push the shoulder back .030 from the standard Dasher since extra capacity would be gained by the longer neck to ideally end up with similar overall capacity as the Dasher (I'd prefer not to end up in the "finicky" zone when capacity goes above the Dasher). Time consuming project, but after a day of forming and trimming large batch of brass, you'd have a lifetime of firings with Lapua brass...and hopefully improved barrel life with ability to handle wider range of bullets given the longer neck.
RAG -
Howdy !

Well... here goes......

Former Savage Arms engineer and internal / external ballistics expert Robert Greenleaf had talked about what he called the powder combustion " turbulence point ", as it relates to shooting ammo in rifles.
Mr. Greenleaf told us: for better / best barrel life, keep the powder combustion turbulence point inside the casre neck.

The virtue of a long ( enough ) neck on rifle cases is that they keep the powder combustion "turbulence point" inside the neck of the case; and not out in the throat / leade'. The .243Win ( example ) has a short neck that does not keep the turbulence point inside the neck, and the .243Win is not well known for long barrel life.

IMHO - I am skeptical a .030" shoulder shove downward on the Dasher for a longer neck, would necessarily equate to ability to use the resulting long-er neck to hold more powder than the stock Dasher ?
Realistically.... if you shoot ( an example ) 93% load density using your chosen powder; would it actually be up inside the neck ?

The most likely instance where powder would be up-into the neck, would be when powders w/ comparatively slow-er " burn rates " are utilized along w/ long enough barrels to boost rifle " expansion ratio ". In other words, give the ( slow-er ) powder gases more time to expand. The peak pressure occurs within the first few inches of barrel beyond the chamber ( according to reknowned ballistician Homer Powely ). Longer barrel... more opportunity for combustion gasses to expand.....more Mv ).

If / when the the neck is only holding the bullet and not any powder, the virtue of the long neck then;
is simply to hold the bullet. A long neck is viewed by some a beneficial when shooting those l-o-n-g VLDs.

When you talk about shoulder shoves downard on a 6mm calibre case, to hold control powder charge amounts and also embrace use of a long-er neck; Mike Walker's " 6 X 250 International ( Walker ) " comes
immediately to mind. An updated version of his wildcat could be made by forming cases from SR-primed
Lapua .22-250 brass. As was pointed out by Urbanrifleman, one way to go is... you could shoot the larger capacity case with less powder in it ( a charge still equivalent to a notional " 6 Dasher, Long Neck ".

I'll send along a pic of my " DEEP 6 " wildcat, which is a chambering cut by running a 6mm Remington reamer in " short ", for a nominal .466" base diam. I use 7 X 64 Brennekke brass, as the parent case.
This wildcat has a .350" neck lg, and case capacity of 51.2gr H2O.

My rifle has a 29" SS Broughton 5C-rifled 1-8 barrel. I like to shoot highload density when I can, and am currently testing loads using RL-23, RL-25; and RL-26. I'll try to include a pic that shows how far up in the case my powder charges rise. I am shooting Sierra 95T-Mk which completely occupy the case neck.
Charges listed are safe on pressure in my rifle / my loads, and represent the max charges; based on case expansion after firing.

Long barrel..... slower " burn rate " powder. For me.... that's the plan.


With regards,
357Mag
 

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RAG -
Howdy !

Well... here goes......

Former Savage Arms engineer and internal / external ballistics expert Robert Greenleaf had talked about what he called the powder combustion " turbulence point ", as it relates to shooting ammo in rifles.
Mr. Greenleaf told us: for better / best barrel life, keep the powder combustion turbulence point inside the casre neck.

The virtue of a long ( enough ) neck on rifle cases is that they keep the powder combustion "turbulence point" inside the neck of the case; and not out in the throat / leade'. The .243Win ( example ) has a short neck that does not keep the turbulence point inside the neck, and the .243Win is not well known for long barrel life.

IMHO - I am skeptical a .030" shoulder shove downward on the Dasher for a longer neck, would necessarily equate to ability to use the resulting long-er neck to hold more powder than the stock Dasher ?
Realistically.... if you shoot ( an example ) 93% load density using your chosen powder; would it actually be up inside the neck ?

...
Right. This is all pretty much what I was thinking.

Oh, in regards to my suggesting a possible .030 push back of the Dasher shoulder, this was simply to achieve a more balanced total volume, as benchrest competition is showing that the Dasher is on the edge for ultimate accuracy and many are leaning towards the 6BRA these days (either are super accurate and easier to tune, and keep in tune, than the larger volume 6mm alternatives). So the neck length I was picturing for this hypothetical Long Neck Dasher, or long neck BRDX, would be any where between .33" - .4" when forming from 6x47L (or even 6GT could be good parent base)...resulting in a neck length of anywhere from .33 - .4".

I also know PO Ackely believe the steeper shoulder angle aided in all of this as well, which the Dasher already has. Of course, the Dasher is good in this respect already.

I personally would like to stick to Dasher volume or lower. Otherwise, I suppose an easy one would be to take Alpha GT brass and just push the shoulder back a little. Otherwise, no doubt, forming a long neck dasher would be a lot of work, akin to how the GT was at first made from 6.5x47L brass...only now you could take the Alpha GT brass and form it to a long neck Dasher with choice of neck length.


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