Hello.

I had not heard of this prior to the Vltor VIS Thread, and I wanted learn more about it.  How does it compare to other alternative bolts such as LMT's and L-W's?  Can they be had?  Also, are the dual extractor springs interchangeable with standard extractor springs?

My standard bolt works fine, but I hadn't seen this mentioned on the board and my searches didn't turn up anything...

See: knightarmco.com/slicks/E3%20Kit04.pdf.

tag.
saw that too.

I have not read the thread you mentioned but I'll tell you what I know about the KAC bolt.

First, there are two versions of the KAC bolt.  They were both created a few years back.  I have copies of the patent and the pdf you linked but don't have the patents available to me at this moment, so this is all from memory.

They were never released for public consumption so finding any kind of feedback from end users will likely be impossible.  Unless you find a guy who knew a guy in KAC who got him one maybe, and if that's the case, they are friends with someone inside KAC and probably not exactly the most unbiased source.

Here's the details of the two versions as best I can remember.  I'll be working off a standard AR15/M16 bolt for reference.  First, what the 2 KAC bolts have in common:

Extractor uses dual springs and if I remember correctly the patent also mentioned a helper detent.  I believe that is what the dot between the two extractor springs on the extractor (look closely) is associated with.  The pivot point of the extractor has been moved forward to increase the leverage the springs have to hold the casing in place.

Next, if you look at a standard firing pin you'll see that the main shaft starts off thick and then suddenly tapers thinner and continues that width to the tip.  KAC moved the point where it tapers back further.  This allows the cam pin hole to be shrunk.  That allows the cam pin diameter to be shrunk where it interfaces with the bolt.  This allows the bolt to have a smaller hole for the cam pin, strengthening the cam pin area massively.  The top part of the cam pin is still standard diameter so the KAC bolt/fp/cam pin combo can be used in a standard bolt carrier.

I thought there was a mention about something done to the ejector or ejector hole (fluting it length-wise for self-cleaning debris channels or something, I forget), but that might have been LMT's Enhanced Bolt's patent.  I aquired and read them both at the same time so I don't remember which it was or what the modification was exactly.

Lastly the differences between the two KAC bolts.  One was made to be a drop in unit and uses standard locking lugs.  The second has modified, radiused locking lugs as seen in the picture on the left in that pdf.  This bolt requires a different barrel extension though and is thus not compatible with existing barrels.  However the locking lugs are strengthened significantly as all the 90* cuts have been removed from the design.  And as anyone with even a basic knowledge of engineering knows and arch is MUCH MUCH stronger than using 90* angles.

I've begged KAC to mass produce this bolt since I first read about it.  Based on appearances and study of the patent, I still believe it to be the most promising bolt design to date.  All issues with the standard bolt (generally extraction, broken lugs and breakage at the cam pin hole) have been addressed with clever, proven designs.  With this design materials used can most likely remain the same, no need for more expensive exotic materials and with todays equipment, manufacturing should not be much more difficult.  Too bad we'll probably never see it.

Hi Paul!  Long time no see, I had to dissappear for some months but I am back now!  It's easy to remember the details of a product you are really excited about.  Speaking of products I am really exciting about, I see your 16" midlengths are about ready to roll off the line.    They look beautiful.

Thanks for posting, wyv3rn.  Good, thorough information!

Quoted: Lastly the differences between the two KAC bolts.  One was made to be a drop in unit and uses standard locking lugs.  The second has modified, radiused locking lugs as seen in the picture on the left in that pdf.  This bolt requires a different barrel extension though and is thus not compatible with existing barrels.  However the locking lugs are strengthened significantly as all the 90* cuts have been removed from the design.  And as anyone with even a basic knowledge of engineering knows and arch is MUCH MUCH stronger than using 90* angles.

Thanks to General_Tso and wyv3rn to taking this on spotlight.

Couple of months ago I made question about barrel extension I saw on Oberland Arms rifle.

Pictures can be found here: www.ar15.com/forums/topic.html?b=3&f=12&t=263159

MN

interesting Markus. Haven't noticing that before !!

on their websight it says it needs a propriertary barrel extension. So you wouldnt be able to just slap one in if you found one.  That oberland arms extension does look like it could work possibly with some work.

Quoted: interesting Markus. Haven't noticing that before !!

Definitely.  Haven't seen that before!

does it mean Oberland use proprietary bolt lugs ?

As far as I know, they don´t. That rifle came with standard bolt and carrier, as you can see.
IMO, they [Oberland Arms] decided to make their own barrel extensions instead of standard which has to be purchased from that side of pond.




ETA: fixed pics

MN

Now that I'm at work, I've been able to grab my docs and look up USPTO #'s.

KAC E3 Bolt Patent:

patimg1.uspto.gov/.piw?Docid=06609319&homeurl=http%3A%2F%2Fpatft.uspto.gov%2Fnetacgi%2Fnph-Parser%3FSect1%3DPTO1%2526Sect2%3DHITOFF%2526d%3DPALL%2526p%3D1%2526u%3D%2Fnetahtml%2Fsrchnum.htm%2526r%3D1%2526f%3DG%2526l%3D50%2526s1%3D6609319.WKU.%2526OS%3DPN%2F6609319%2526RS%3DPN%2F6609319&PageNum=&Rtype=&SectionNum=&idkey=458361E0B55A

LMT Enhanced Bolt Patent:

patimg2.uspto.gov/.piw?Docid=06182389&homeurl=http%3A%2F%2Fpatft.uspto.gov%2Fnetacgi%2Fnph-Parser%3FSect2%3DPTO1%2526Sect2%3DHITOFF%2526p%3D1%2526u%3D%25252Fnetahtml%25252Fsearch-bool.html%2526r%3D1%2526f%3DG%2526l%3D50%2526d%3DPALL%2526S1%3D6182389.WKU.%2526OS%3DPN%2F6182389%2526RS%3DPN%2F6182389&PageNum=&Rtype=&SectionNum=&idkey=A9861E0F59DE

I have copies of these docs without all the patent office webpage fluff, but this is the best I could find for your consumption, sorry!

Thanks for all the good info, everyone.

Quoted: Thanks for all the good info, everyone.

+1