Hi there,

Tannery advertise different material for their 80% lower from Titanium to T6 Aluminum. I would like to know if anyone has experiences with materials other than T6 ? Does the higher price material really provide stronger/more reliable performance ? Will it be more difficult to machine material such as Titanium ?

Hey Hycheng,
First the T6 refers to a heat treat method, the actual alloy of the cast receiver is 356T6, it is strong but I believe only half as strong as the forged aluminum variant, which is constructed of 7075T6. I believe the Titanium ones are milled not cast but I could be wrong. And yes Ti is a LOT stronger than Al. But what that means to the case of the AR-15 lower I do not know. just a thought.

The material used for lowers is for the most part unimportant, unless you bugger it up. There is very little stress put on the lower. At most, a little wear around the pin holes and a little stress on the tower when the carrier slides back.

If you don't have a good fit between the upper/lower, additional stress may be put on the takedown pins and tower, which is usually the cause for most problems of this nature.

The Ti is much stronger, but has nothing to do with reliable performance, only that it may take the stress better than other materials. Ti is much more difficult to machine than cast aluminum and will require use of more expensive tooling.

Avoid cast aluminum.   If using aluminum, use only forged lowers.

Titanium is great stuff, but do you have the tooling it takes to mill it?

You will have to be using replaceable insert tooling to work with titanium, and the inserts must be specific to titanium if you want them to last for any length of time at all.   That's expensive tooling.

Check for Sandvik and Coromant brand tooling, as a starting point.  It's available, but not cheap.

CJ

After reading cowboy's comment in this thread [url]http://www.ar15.com/forums/topic.html?b=3&f=4&t=166790[/url] , I do have some concern on the strength of cast AL. However, Ti seems to be an expensive proposition. So what is the best trade off between price/strength/tooling among Tannery's offering : 356/T6-AL, CMM Ceramic metal, Stainless steel, AL/Bronze or Ti ?

At least what will work with regular toolings ?

Thanks again.

William is getting 80% forged lower pretty soon according to his web site.