205M versus 205ARM Primers

[peaceatwar]

205M versus 205ARM Primers

I am getting started in .223 (Starting with a bolt gun) and I have 2k 205AR Match Primers.

Things I know:

• They will function
• You will take them if I don't want them
• Why don't I shoot them and I find out

Things I would like to know:

• What are the differences? I have read something about "cup" size. What does that mean?
• Is the 205ARM a bad choice of a primer for a bolt gun for any reason?
• How much, if any variance should I expect if/when I switch to 205M Primers. I am imaging I will likely need to re-develop loads. Is this true?
• If the problem isn't money is it worth to save the 205AR primers for an AR and acquire some 205M primers for the bolt gun and not worry about it?
• Do you have any personal experience with this? Care to share?

 

[mkollman74]

I have useed these intercahangeably. My understanding is the difference isn't the cup size, but rather the cup hardness. The AR match cup is intended to be a bit harder to help prevent the possibility of a slam fire. I have never had this experience with regular match primers in my ARs, but I know others who have. You shouldn't need to re-work loads when switching between the two (I never have). You may, however, want to pay attention to whether you are getting any significant indentation on the primer after the bolt slams forward on your AR if you are going to the 205M (before you pull the trigger of course).

As for using the 205ARM in your bolt gun, it shouldn't pose any problems.

 

[peaceatwar]

Thanks for the update. Anyone else?