Todays laugh!

[cory]

Agreed. I guess I should have clarified my last a little better. I was referring to all AR15/M16/M4 bolts when I said "The bolt lugs should be much rounded with fewer, wider lugs. (Without the grammatical error. haha)"

[IceAxe]

From what I have researched all the enhanced bolts that are made to fit the mil spec extension have experienced breakages, even Sharps new highly radius-ed bolt, without regard to the material. My preference would be for a hybrid that gives up some of the extensions inside radius for expanding the bolt's outside radius. Though I have never broken any bolt personally, what I have seen would indicate a weakness or a higher stress being applied on either side of the extractor. Physics tells me that if I double the diameter of the cartridge I will get 4 times the area or force at a given pressure. Why not build a better bolt?

[LRRPF52]

From what I have researched all the enhanced bolts that are made to fit the mil spec extension have experienced breakages, even Sharps new highly radius-ed bolt, without regard to the material. My preference would be for a hybrid that gives up some of the extensions inside radius for expanding the bolt's outside radius. Though I have never broken any bolt personally, what I have seen would indicate a weakness or a higher stress being applied on either side of the extractor. Physics tells me that if I double the diameter of the cartridge I will get 4 times the area or force at a given pressure. Why not build a better bolt?

That Relia-bolt proved to be one of the most brekage-prone bolts on the market, for a premium price too. The choice of steel was not really an appropriate one for starters. Upward learning curve on heat treating with S7 on such small AR15 lug geometry also seemed to contribute to the failures.

The only bolts I have broken in the AR15 have been in 5.56 chambered guns run on a tortuous firing schedule, CLGS, with a lot of M855 and Winchester White Box. The AR15 was designed at a time when the final SCHV cartridge had not been realized yet, and was built around .222 Remington with 50,000psi SAAMI MAP (Maximum Average Pressure or working pressure of the cartridge set by SAAMI).

Are you talking about increasing bolt body diameter, or outer diameter of the bolt lugs?

Knights Armament did a nice approach to this with their E3 bolt and extension.




LMT also uses Aermet alloy on their enhanced bolts, which is a good prescription for the 7.62x39 guns, but extractors still break with the .124" bolt face depth limitations on extractor lip geometry, and the enhanced LMT bolt extractors are proprietary lobster tail designs.

[IceAxe]

I was thinking the outer diameter of the bolt lugs. I like the looks of the faxon bolt used in the arak, though I am not sure what diameter is used. I recognize that is a piston system with a propriatary upper. I can't find any evidence of a mil spec extension ever failing as in breaking a lug. I think some material could be "traded" from the extension to bolt lugs. As the outer radius of the bolt lugs increases it would also scale to a wider lug.

I am not familiar with the E3...are these available with an extension?

[IceAxe]

Thanks for the tip on the E3, I sent them an email to see if I can get one with the extension and any other requisite parts.