furrybean Posted July 3, 2011 Report Share Posted July 3, 2011 If using a bushing die to do this do you go straight to the final neck diameter or get an intermediate bushing and do it in two operations? Link to comment Share on other sites More sharing options...
n8ess Posted July 3, 2011 Report Share Posted July 3, 2011 If using a bushing die to do this do you go straight to the final neck diameter or get an intermediate bushing and do it in two operations? I have done it in one but I was not overly impressed with the results, I then thought should I go down the root of an intermediate bushing die? My answer would be go for Nosler custom brass, it's as good if not better finished than my 6BR Lapua brass. Drilled and de-burred flash holes, chamfered necks and weight sorted. ATB Neil Link to comment Share on other sites More sharing options...
Davy Posted July 4, 2011 Report Share Posted July 4, 2011 You can neck down in one go, use Imperial sizing wax or similar. You may find the mouth of the case turns in slightly so you will need to run a mandrill down afterwards just to conform the neck is correctly formed. I would neck size, followed by the mandrill stage followed by anneal followed by final size. It sounds like a lot of work but .308 brass is a lot easier to come by than 7mm08 Link to comment Share on other sites More sharing options...
furrybean Posted July 4, 2011 Author Report Share Posted July 4, 2011 It sounds like a lot of work but .308 brass is a lot easier to come by than 7mm08 Exactly. I was quoted almost £1 a go for 7-08 brass but got some once fired lapua for a fraction of that. Link to comment Share on other sites More sharing options...
furrybean Posted July 4, 2011 Author Report Share Posted July 4, 2011 What I've never understood is you buy a precision bushing and then when using an expanded you pull that back through this changing the final diameter?! Link to comment Share on other sites More sharing options...
Davy Posted July 4, 2011 Report Share Posted July 4, 2011 Well..... you don’t actually do that. As you neck down the mouth of the neck can turn in slightly which means that it is now under size, so you pass a mandrel through the neck to bring to open the slightly in turned mouth of the neck. I will see if I can find a case and neck it down with a picture so you see what I mean Link to comment Share on other sites More sharing options...
1967spud Posted July 4, 2011 Report Share Posted July 4, 2011 Link to comment Share on other sites More sharing options...
Davy Posted July 4, 2011 Report Share Posted July 4, 2011 A very quick 7mm08 job! I dont actually shoot this so I had to improvise but you should see the differences. Left is a .308 case fires and cleaned Middle is a .308 necked down to 7mm - this one went quite well but you should be able to make out a slight buckling top left Right is a.308 necked down to 7mm and the opened slightly with a mandrel These are all scrap brass with no preparation but hopefully show what I mean Apologies for the crap picture. Link to comment Share on other sites More sharing options...
furrybean Posted July 4, 2011 Author Report Share Posted July 4, 2011 Brilliant thanks. Do you use the expanded that cones with the redding die set?? Link to comment Share on other sites More sharing options...
Davy Posted July 4, 2011 Report Share Posted July 4, 2011 I use a Sinclair International Expander die and turn my own expander mandrels to suit, however you can also buy them http://www.sinclairintl.com/.aspx/pid=38807/Product/Sinclair_Generation_II_Expander_Dies# Building my own is handy as I can build mandrels for very specific uses. I recently built a neck expander for a .303 that also flares the mouth very slightly so it just contacts the inside of the chamber neck and centralises the case when using lead boolits K&M do something similar as well. I seat my expander die on a thick O ring so it floats and goes with the case neck instead of against it which reduces neck run out. Link to comment Share on other sites More sharing options...
Davy Posted July 4, 2011 Report Share Posted July 4, 2011 There ya go! Link to comment Share on other sites More sharing options...
furrybean Posted July 13, 2011 Author Report Share Posted July 13, 2011 Just talking to a guy about this. If the od of a necked down and seated round is .313 and the fired cases (7mm08 ones) are normally about .317 would this mean there is 4 thou expansion possible and is this enough not to overpressure. Link to comment Share on other sites More sharing options...
Davy Posted July 13, 2011 Report Share Posted July 13, 2011 Not sure what you mean here. .313" built means a brass thickness of .0145" which is a bit less than I would expect but this does depend on brass make. .317" gives a brass thickness of .0165" which sounds better. The neck tension is going to be down to what it was sized to prior to bullet seating and the only real way a loaded round would vary from .313" to .317" would be either using different brass or neck turning one. Yes there is going to be a slight difference in neck thickness after necking down but I would be surprised if it was two thou less than a normal case, in fact I would expect it to go the other way. Of course I could be totally missing the point here! Link to comment Share on other sites More sharing options...
furrybean Posted July 13, 2011 Author Report Share Posted July 13, 2011 Sorry not very clear. Fired brass OD is .317 Necked down brass with bullet seated .313 I presume therefore I have a clearance of 4 thou with my bullets using lapua .308 brass Is this enough to be safe? Cheers and hopefully I make more sense now Link to comment Share on other sites More sharing options...
Davy Posted July 13, 2011 Report Share Posted July 13, 2011 There will be some spring back so the fired measurement of .317" is going to be slightly under the true chamber neck size. In the absence of a drawing for the chamber reamer you can do a cold cast of the chamber if needed to confirm this. Sized and seated brass at .313" gives two thou all round which is fine, not a problem at all for a rifle used in the field. Different people shoot with different neck clearances for different disciplines. As an example my AI has quite an open chamber at the upper NATO limit so probably two and half thou all round which is good as it allows for dirty ammunition to be used in volume if needed, whereas a BR shooter may be running with one thou clearance. My F Open rifle is a tight neck and I run with just over a thou and a half as I can shoot more in a detail than a BR shooter, the extra clearance is to cope with any carbon build up over the 22 shots. Link to comment Share on other sites More sharing options...
furrybean Posted July 13, 2011 Author Report Share Posted July 13, 2011 Tip top cheers. Im just US cleaning the brass now ready to start sizing Ta muchly.... ....for now lol Link to comment Share on other sites More sharing options...
Davy Posted July 13, 2011 Report Share Posted July 13, 2011 Oh good news, post some pictures! Link to comment Share on other sites More sharing options...
furrybean Posted July 13, 2011 Author Report Share Posted July 13, 2011 Well I did it in my crude way. As Im waiting on the bushings I used the hornady neck sizer with mandrel to take the necks down to 7mm and then bumped the shoulders back with the redding body die. I took the die down slowly until the shoulders didnt restrict the bolt closing.. The brass chambers nicely so Ill trim up and get some loads done. happy days Link to comment Share on other sites More sharing options...
Davy Posted July 13, 2011 Report Share Posted July 13, 2011 Sounds good, got any pictures to post? One thing to remember is make sure you have not bumped the shoulder too far back, if you are building with a jump and the shoulders are too far back the firing pin will hit the primer and instead of igniting it the case will just move forward. I have this problem with my 7mm SAUM based wildcat with new unfired brass. The way to get over this is build long (jammed) or create a false shoulder. Link to comment Share on other sites More sharing options...
furrybean Posted July 13, 2011 Author Report Share Posted July 13, 2011 I hope not. I moved the die about 1/16 until I got good bolt closure. I might make 20 up and try them. If they're okay then carry on and resize the rest. Link to comment Share on other sites More sharing options...
furrybean Posted July 13, 2011 Author Report Share Posted July 13, 2011 I'll get some pics done in the next few days Link to comment Share on other sites More sharing options...
furrybean Posted July 14, 2011 Author Report Share Posted July 14, 2011 .308 - Necked Down - Shoulders Bumped Link to comment Share on other sites More sharing options...
Davy Posted July 14, 2011 Report Share Posted July 14, 2011 Good fun this reloading lark isn’t it? Link to comment Share on other sites More sharing options...
furrybean Posted July 14, 2011 Author Report Share Posted July 14, 2011 Lets see what results I'll get with them. It saves £90 odd quid on Nosler custom brass so I'm happy if they shoot well Link to comment Share on other sites More sharing options...
furrybean Posted July 17, 2011 Author Report Share Posted July 17, 2011 yet another quick question. Ive made some rounds up and they chamber fine. When I examine the round there is a small patch where the neck touches the chamber. Will this really make a difference to normal hunting accuracy or do I need to buy a neck turning tool Link to comment Share on other sites More sharing options...
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