6mmBR Posted May 13, 2007 Report Share Posted May 13, 2007 Just a quick one, when my rifle comes back from Border I will need some fireforming loads to get the formed brass. I know I need to seat the bullet into the lands by 10 thou to keep the case head spaced ok. What I want to know am I better using a powder on the fast side of the spectrum or one on the slower side? Along the lines like N135 or N150? I also have 540 and 550? Cheers Dave Link to comment Share on other sites More sharing options...
Ronin Posted May 13, 2007 Report Share Posted May 13, 2007 Dave I used a heavy bullet (60g Sierra HP) which are long and loaded them with a MAX load from the Sierra book for standard 22-250. They were loaded 0.010 - 0.020" into the lands so that the case head was forced back onto the bolt face. Squeeze trigger and your 22-250 case becomes a 22-250 AI - I recall using 41grains of H4831SC BUT CHECK THIS BEFORE USING PLEASE. I'm not sure what twist your barrel is, but if it is a fast one like mine (1-8" twist), I would recommend trying Moly 75g A-Max and 39.5g of RL22 = 3000fps and an ES of 9fps AGAIN please work up to this if you use it... Andy Link to comment Share on other sites More sharing options...
Guest Smeagle Posted May 13, 2007 Report Share Posted May 13, 2007 The simple quick answer is go as fast as is safe to do so. You want rapid expansion to form the case as evenly as possible. Stick within the limits though. Link to comment Share on other sites More sharing options...
varminter Posted May 13, 2007 Report Share Posted May 13, 2007 Agree with the others boys here , When i had a 243 ackley with a 1 in 9 twist , i loaded the 105 a-max 10 -20 thou into lands and i used a fast powder for bullet weight ( i was using H4895) .. Never had any problems fireforming using this method All the best............. RAY......................... ;) Link to comment Share on other sites More sharing options...
6mmBR Posted May 13, 2007 Author Report Share Posted May 13, 2007 She's going to have a 1in12 twist, so I'll probably go for a 55vmax and N135 which is the faster of the powders I have. Thanks for the replies guys. Dave Link to comment Share on other sites More sharing options...
Vermincinerator Posted May 13, 2007 Report Share Posted May 13, 2007 Hi Dave, JR will confirm this, in a properly cut Ackley chamber you will not need to seat the bullets into the lands. The chamber should be cut about .004" shorter then the standard chamber resulting in some crush of the case shoulder and resistance when closing the bolt. Many smiths, if they dont have dedicated Ackley headspace gauges will use the "GO" gauge from the parent case as a "NO-GO" gauge and use an unfired case as the "GO". A simple test is to close the bolt on a new unfired case, if you feel more reisitance on closing the bolt then usual then the chamber is correct. If you dont feel any noticeable resistance then your chamber has been cut to deep and you will have an excessive headspace condition. Ian. Link to comment Share on other sites More sharing options...
6mmBR Posted May 14, 2007 Author Report Share Posted May 14, 2007 Cheers point noted, I expect JR will let us know. Cheers Dave Link to comment Share on other sites More sharing options...
6mmBR Posted May 23, 2007 Author Report Share Posted May 23, 2007 Andy what trim length do you use on your formed brass? Cheers dave Link to comment Share on other sites More sharing options...
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