300 blackout primer question

[hundy]

I have been realoading for years. That said the 300blackout is very new to me. I have about 400 5.56mm cases that I have cut down with a jig and small chop saw. I have shaped them with my dies and they are to spec.
All that done, I am not sure with primer to go with.
I am not sure if I should stick with cci#41 or go with small rifle magnum.

I am planning to use these loads in a AR style rifle, 16" barrel
I have 150gr and 168gr bullets and plan on using IMR4227

On some sources it mentions Small rifle Mag, and on others it just says small rifle.

Any help is appreciated

Thank you
Jay

[highpower790]

A rem 7 1/2 or wolf magnum should be good.

[Germz]

is use fed 205's. sometimes #41's. but magnums? not really needed.

[Victor Cachat]

I just finished a batch using Remington 6 1/2 small rifle primers.
They worked fine on my .223 loads and there is less volume in the 300 case.

[Jeff213]

I use cci 400s becuase they are available locally for $30 a brick. Work fine for me.

[Kmai24]

I just finished a batch using Remington 6 1/2 small rifle primers.
They worked fine on my .223 loads and there is less volume in the 300 case.

+1^^

Been using these for both 223 and 300aac/blkout. Never had a problem yet. I'm loading 150gr hornady FMJBT with accurate 5744 which I heard has a similar burn rate as imr4227. Good luck OP, very fun round to load and shoot

[god_father]

I've used cci 400's as well as wolf magnums and both worked fine.

[mif_slim]

I use any SRP and it works fine.

[mjmagee67]

Well I use Winchester small rifle and Tula 223 primers, so any small rifle primer seems to work.

[wild_weasel]

I have tried Tula 223, Winchester SRP, CCI #41, and CCI 400 under H110 with no problem in my H&R/AAC Handi with no issues.

[bigedp51]

When Remington and Winchester ran Lake City they didn't use CCI #34 or #41 primers and Remington used their standard 7 1/2 and 9 1/2 primers in military ammunition. Meaning it is marketing hype to charge more for CCI #34 and #41 primers.

Warning:
Remington does not recommend this primer for use in the 17 Remington, 222 Remington, 223 Remington, 204 Ruger, 17 Remington Fireball. Use the 7-1/2 Small Rifle Bench Rest primer in these cartridges.

This 6-1/2 Small Rifle primer is primarily designed for use in the 22 Hornet.

http://riflemansjournal.blogspot.com/2009/06/primers-small-rifle-primer-study.html

[Germz]

Warning:
Remington does not recommend [6 1/2] primer for use in the 17 Remington, 222 Remington, 223 Remington, 204 Ruger, 17 Remington Fireball.

Use the 7-1/2 Small Rifle Bench Rest primer in these cartridges.....

NEVER use Remington 6 1/2 primers with high pressure cartridges, the cups are thinner and in AR15 rifles the 6 1/2 primers can cause slamfires and ruptured primers.

correct me if I'm wrong but did you just post saying to use benchrest primers in a autoloading rifle? More specifically, one with a floating firing pin??

I thought bench rest primers have thinner cups so as to be more easily ignited by light triggers in bench rest weapons

[LynnJr]

Benchrest shooters typically load there rounds well above book max.

Primers are used to tune away the extreme spread in your loads.
You normally want the lightest primer that will ignite your load without blowing the powder halfway down the barrel. If your extreme spread is too high you can go up 0.1 grains and see if it shrinks. If it doesn't shrink or it increases you swap out primers and re-work the load.

The magnum primers like the CCI 450 Magnum can handle higher pressure without cratering or popping so they get used in very long barrels and loads near the ragged edge.

[bigred1]

I run nothing but #41s.

hornady 150fmj, 17.3gn 4227, CCI #41 w/ coal 2.145

[hundy]

Thank you

Thank you for all the help and advice. I appreciate it. I have a brick of #41's for my 5.56mm loads, so I will stick to that. Just based on availability.
Thanks for your replies, this information helped.

Thanks
Jay