Small Base Dies

[wvuredneck09]

As a benchrest guy I only currently own bolt actions, for which I use FL and or Neck dies. However I am getting the funds and ideas together currently for an AR-10 project chambered in 308 Win. Are small base dies really necessary for a semi auto. I'm concerned with over working my brass if there is no need for these. Any experience out there on this subject? Also I have another thread going with questions about the build that I have gotten no response to. If there are any AR guys out there with advice I want to hear it. Thanks

 

[msnations]

My experience is mainly in ar15s, but i also have an ar10. small base dies should not be necessary as long as you use a chamber appropriate for semi-autos. As far as building an upper goes - the only bit that really matters is getting a good barrel. If i were getting a barrel i'd either get a finished barrel straight from krieger, or buy a blank and send it to Compass Lake Engineering for finishing.

 

[wvuredneck09]

by chamber appropriate for semi-autos i assume u mean not as tight as a bolt gun correct?

 

[msnations]

semi auto chambers usually have generous necks approx .004' to .006' larger than a loaded round. usually the rest of the chamber body is enlarged slightly less, and will maintain the appropriate case body taper.

the problem with most semi-auto chambers is actually that they are unnecessarily large. My personal rule is that if you can fire a moderate round and the spent casing will completely rechamber, then your chamber is too loose, resulting in lost accuracy and overworking your brass.

 

[oldreliable45120]

Full length should be fine, unless it is a tight chamber. I only use a small base for when I get alot of brass that wasn't mine. I have a friend that works at a range and he gives me buckets full when I need. My DPMS 223 upper has a tight chamber and I have to small base size for that rifle only. All my M1A's and my DPMS 308 has no problem digesting ammo that was full length sized.