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Reloading question


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When reloading for the AR 308 is it better to use a bullet with a cannelure ?    Is it a big deal , or not so much ?  I will have a 20" Match Bull Barrel with a 1X11 twist , should I use small base dies , or just full length re size ?


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Semi-auto rifles - 5.56 and .308 - I hit every round with a light taper crimp.  Bullet setback can ruin your day, ruin your rifle, and possibly much worse.  Not worth the risk.  I hit them all, if they're going through the autoloaders.

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Cannelure bullet not necessary ,but as 98 said , some kind of taper crimp or the new Factory crimp by " LEE " . I'm using them more & more often now & am getting one for all the rifle cal. I load .


I have been using a Taper crimp die for thirty years , with great success .


Small base dies in most cases are un necessary ,but if you load for various rifles , especially , semi auto's, they work well . 

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   Friend 98v5z, respectfully, HOW? can a set back bullet ruin your day, and rifle?

   Ruin a group, yes, but I'v seen many deep seated bullets shot, and not one ruined a rifle.



Terry, some of my 5.56 loads are at the point where they're almost compressed loads.  Especially the heavies.  No crimp, no cannelure projos, and one of those catches going out of the mag and into the chamber - bullet setback, which definitely compresses the load.


Pressure spike, right there, and it's in the chamber, bolt closed on it.  You never get a chance to see it, during the loading process.  Pull the trigger on that one, and the rifle can come apart in your hands.


Not a big deal on a bolt gun, but it's a big deal on the autoloaders.  There's some hellish spring pressure shoving a heavy bolt carrier to load that next round.  One cartridge with a setback projectile can do much more than ruin your day, if it causes that rifle to come apart.


APR, projos with a cannelure are better for the autoloaders, and hold a crimp better, but they're not necessary.

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   I think that this has to be one of the ideosyncontes commen to the AR.

  In the late '60's an through the 70's I sold and re-loaded for a number of Winchester 88's and 100's.  All loads were at, or somestimes over "the book" max.   Especially with the 284 ctg.

   Some of those projectiles got stuffed WAY down in the case, both levering the 88, and self loading the 100.  None, when fired, showed any more pressure signs than did "the normal" rounds.

   Again, I accept as fact that you have seen it personally, and it does happen with AR's. if you do say so.

  Altough I'v got 50 years of  professional gunsmithing experience, I still have a LOT to learn about AR's

   I have already learned that "normal" reloading practices do not always work with the AR.


   Thank you for expanding my education.


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Kinda makes you wonder how many are set back & no one knows it . Might account for some of the flyers, shooters get.


If all the components are with in correct spec's , the cartridge should feed into the chamber smoothly with out much force on the bullets frontal area to cause it to be set back.


Some reloaders just rely on case neck tension as has been described.  

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Being a cheap ass, I first noticed setback on premium pistol ammuntion...the round that would get rechambered multiple times in the 1911 carry magazines.


While I've not noticed it in rifle loads, I'm sure it happens.  When we reload/handload ammo, one thing people tend to forget is that as powder charge volume goes down with a given caliber's case capacity (.223 versus .30-06), the percentage of charge variation increases greatly as a percentage with the same deviation in weight.


In otherwords, if you have a powder charge of 50 grains in a .30-06 loaded and checked to 1/2 grain deviance (a 1% allowance), that 1/2 grain deviance in a 20 grain powder load (same powder) in a smaller caliber becomes a 4% allowance...a potential 8% spread between high and low.  If you're loading at the maximum tolerance for a caliber, you are already pushing that envelope.


Add into that bullet setback and your pressures from round to round may be a source of extreme frustration.


Has anyone done a "setback experiment"?



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I have. What I found was that the bullet actually would sometimes be projected, that is they moved out of the case mouth as much as .002" - .003". So the opposite was happening. The neck tention was not modified & .002". I modified my expander ball of the Forster BR sizing die, .308, to .0035 and this eliminated the projections. Ogives gettig jammed into lands is a bad thing too, if too much, as you know.

M4 feed ramps may reduce chances of setback? And when the violent act of the excelerated loading and then sudden stop in chamber must have caused the projections?

Edited by NoFail
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I remember reading an article about set back on pistol ammo that was repeatedly chambered in carrie & service pistols  , rotate ammo often , because as said above they do set back by being repeatedly chambered.


Not sure how rifle fodder fairs , I for one don't do the same as with my carrie gun . If I feed some thing into my rifles, its shot , but service rifles will most likely suffer from the same set back as pistols, . under the same circumstances. 

Edited by survivalshop
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