As an owner of a newly built Grendel I've been doing plenty of reading and digesting posts about reloading for it. One thing I have noticed is the constant mention of CCI 450 primers in handloads. Is there a specific reason it is almost universally used instead of the 400? I already load for .223 and 300BLK using CCI 400 primers. If the 450 are better in the Grendel I guess I will be stocking them too. Any well founded reasons would be appreciated.
Primers for Grendel reloading
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I'd like to hear a well informed answer to this too. I load a lot of .357 mag & .44 mag rounds and have run up against std vs. mag primer shortages. I've heard the mag primers are thicker to keep from blowing out and some say they've got a hotter charge. They were posted on the internet, so they must be true - right?
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You might find some good info in this thread. http://www.65grendel.com/forum/showt...ghlight=primer
Post #45 on page 5 includes a link to an article and primer comparison chart that's useful.Paul Peloquin
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I've used both 450's and BR4's. The BR4's are harder to seat as they are slightly wider. They are also shorter so seat shallower. Given the 450's seat below the level of the case base I don't need them any shallower.
I keep the BR4's for old worn out cases.
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Originally posted by biodsl View PostYou might find some good info in this thread. http://www.65grendel.com/forum/showt...ghlight=primer
Post #45 on page 5 includes a link to an article and primer comparison chart that's useful.
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Originally posted by MrDraco View PostIt's not that the 450's are better for the Grendel, it's that for the AR15 (and almost any semi-auto rifle) slam fires do happen and are more common than people think. The thicker cup of the 450's reduce the chances of this happening.
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Originally posted by dpete View PostI understand that slamfires can and do happen but how often? Is there an actual empirical data reason for using a magnum primer in what definitely is not a magnum cartridge? Does it burn hotter producing a more uniform explosion and therefore better groups? My experience with my LR308 AR is that the only difference I have seen is that the powder charge can be reduced using the 7.62 designed CCI primer vs. the #200 large rifle primer. I would think a slam fire in a .308 caliber AR would be more common than a .223 given the huge difference in BCG size and moving mass. Never had one, and never have even seen a dimpled primer while ejecting bullets doing ladder tests.
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It's not just about slam fires or if magnum primers deliver more kick, it's about containing pressure. Magnum primers have thicker cups and so are able to contain pressure in hot loads.
F-Class .223 shooters use magnum primers to load over SAAMI and so reach 1,000yds with long barrels and 80gn projectiles. They also use bolts with narrower firing pin holes for more support. From all the posts I've read on this forum Grendel owners tend to load hot to compensate for the lack of velocity from a small case. Claims by posters that manufacturer data is overly conservative and it is OK to load hot because the cases seem to last and not too many bolt lugs get blown off is mitigated by using quality brass and thicker cups to contain this over-pressure. Also knowing what you are doing and being precise about it helps.
If your firing pin is reasonably free to move in the carrier you will see a slight mark on ejected unspent round. Probably an irrelevant fact to say I have never seen a slam fire because military ammunition is thick-cupped to prevent it.
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