I was looking on Sierras web site and they don't show a 77 grain bullet with a cannular is that because they wont/don't/cant  sell it commercially?  I do see on Midways web site though the 77 grain Blackhills they sell is used by the military is that the stuff their marksman units use for competition? How necessary is the cannular I mean is it something really needed or just a military spec?
Thanks,
Mike

NO, not needed.

FWIW, there was a guy at one time selling "cannelured" SMKs or IIRC around $80 gets ya good cannelure machine so you can do your own.

Mike

ps - been shooting the 77grn SMKs for more than 5 years now, and only tried 100 rounds cannelured, (bought off the EE), no advantage I could see.

the cannelure is for crimping.

If you are using the 77's for single shot/load part of the NM, chances are you have them loaded out also so there isn't so much of a jump to the threads, ala effecting accuracy.  
In my Bushy DCM I load out the 69's a bit, and load them on a sled.  all others in the rapid stage are to mag length.

+1 not needed.

HP shooters have been using 77's for years in rapid fire stages loaded to mag length with no issues of set backs.
The cannular that Nosler & Sierra put on for the Mil is pretty mild/ insignificant as cannulars go..

Quoted: the cannelure is for crimping. If you are using the 77's for single shot/load part of the NM, chances are you have them loaded out also so there isn't so much of a jump to the threads lands, ala effecting accuracy.   In my Bushy DCM I load out the 69's a bit, and load them on a sled.  all others in the rapid stage are to mag length.

FYI, Sierra Matchkings are NOT designed to be loaded long as the ogive on them is quite different than the ogive on Hornady's line of bullets, (ie. the 75grn A-MAX, which is a bullet that loves to be "close" to the lands).

Sierra bullets love to "jump" into the lands and if your loading them close to the lands your probably NOT getting optimal accuracy outta them. They were designed and conceived to be loaded "mag-length", especially the 77grn SMKs.

Take it you were unaware of this information.

Mike

ps - yes I have shot them for years from the 600 yard line in "F" class HP matches and briefly in x-course SR, as well as out to the 1k line, all loaded mag-length.

Sierra bullets love to "jump" into the lands and if your loading them close to the lands your probably NOT getting optimal accuracy outta them. They were designed and conceived to be loaded "mag-length", especially the 77grn SMKs. Take it you were unaware of this information. Mike

I in fact did not know that about the 77's mike...

As I said, I've been using the 69's from Sierra, and the 68's from Hornaday.

Thanks for the tip

But then again, I'm a transferred .30 cal serviceriflemindset guy....Been shooting the AR in the matches only about 4 years now...Was always an m1a guy.

What about non-match purposes, shouldn't one be concerned with bullet setback in a cartridge that is already running redline pressures?

Quoted: What about non-match purposes, shouldn't one be concerned with bullet setback in a cartridge that is already running redline pressures?

FWIW, the only 5.56 pressure load with the 77gr SMK or Nosler bullets is the Mk262 that Black Hills is loading, and I'm pretty sure both of these have a cannelure. Hornady does load a 5.56 75gr OTM in their TAP line, but that does not have a cannelure, as far as I know. I'd hazard a guess, that if they thought it was an issue, they would add a cannelure.

Other than preventing setback, a cannelure *may* help with fragmentation.

The Sierra bullet that is used in Mk262 isn't available as a reloading component, IIRC.

Lots of match shooters shoot hot loads for the 600 and 1000 yard lines... I'd guess most of them are not concerned with bullet setback either with long loads, or mag length loads. It shoudn't be an issue with good neck tension and/or a slight crimp (maybe a case for the Lee FCD)

If this is a reloading question, you might get better answers in the reloading forum.

Although I agree that most of the time it is not needed.  I hunted with Hornady 75 grainer match ammo one year, and after loading the same round several times.  The bullet did set back a bit.  I did not shoot it.  I personally would feel more comfortable with a cannelure for Defense ammo.  But I'm not taking away from what mr. wilson said or any of the others, they have enough experience with it that they probably are comfortable with it.

I shoot the 75 OTM without the cannalure, SR applications.  I use the Redding .244 neck bushing when FL sizing and use no crimp.  So whatever tension that applies(# is escaping right now) is what holds the bullet in the case.  I tried to pull a bullet for the hell of it.  Using two huge channel lock pliers and every leveragable position I could think of, the bullet wouldn't move.  I was able to push it into an empty case after several severe blows on the concrete floor using most of my 200 lb. frame.

I gues the point of my rambling is use what makes you feel comfortable.  For me, my bullets won't be cannalured or crimped.  I see no advantage.

The cannelure is out there.

One thing I forgot to say was the one I had set back after loading a bunch was moly.  That might  have something to do with it.

tag.