Major Problem with making false shoulder for Dasher

[AckleyImproved]

Well, I FL sized all my brass, trimmed to length, expanded to 6.5mm... and this is where my problems started.

Going by the reamer drawing, the Dasher shoulder should start at 1.3099", so this is where the cases should be necked back to 6mm. However, when the cases are chambered, they are not headspacing off the false shoulder.,Can not remove one of these cases frommthe rifle, as it doesnt lock into the bolt) So I should bring the false shoulder foward. Easy... not when your neck turning them as well!

The main problem is that when I turn the necks, the case yaw's on the mandrel,but will be kept true on the mandrel), so where my neck turning ends, at the false shoulder, the turning is not an even distance around the case, but the turned part is curved,yawed)!! Does this matter? I will get picture when I can!

I have used Imperial sizing wax during the whole process, and all the cases when sized with out much effort.

I am thinking of ditching the false shoulder, and just headspace off the neck turned portion as my neck is 0.265. Thoughts?

What si my problem. I will bring the false shoulder forward so it is tight to close the bolt, and turn down to this faslse shoulder,with my yawing!) But the measurments will be different to the reamer drawing?

Cheers
AI

 

[AlNyhus]

AI: Why not just turn the necks a bit,.020-.030) past where the new neck/shoulder junction will be, seat a bullet long so it is hard into the rifling and holds the case head firmly against the bolt, and fire 'em using a max. load of a fast burning powder for the bullet weight you're using to fireform with? This will blow the shoulder foward. -Al

 

[Wild_Bill]

Ok this is what i do i neck to 25 cal then neck the case back to 6mm in little steps until the case closes with some pressure on the False shoulder against the chamber DO NOT rely on a drawing for this the cases MUST be fitted to YOUR chamber. Now in your case neck to 6.5 turn 2/3 of the neck or further then neck the case down in small steps starting at 1/4 of the neck and slowly set the bushing down in the die 5 thou at a time on a fresh case until it just closes on the case then do the rest that have only partialy been sized if you have turned further you will never get a doghnut as the brass in the shoulder will be thin and uniform. Dont try to get to technical with this opperation load the case with 30 to 31gr of AR2208 and a 107gr Sierra at least 20 thou into the lands and shoot the rifle for groups you will be surprised i have shot 3/4" groups at 300 yards fire forming my Dasher 271 neck

Cheers Bill
Australia