What mag blocks will do last round bolt hold open usings the normal bolt release on a 5.56mm AR?

It can do

Most top loaders require a 9mm bolt catch.

Some of the bottom loaders will do it without the bolt catch.

OK, then which ones???

Dedicated top loading Hahn.  The only mag block worth getting.

Hahn Mag block  Bottom of the page.  

It's going in a SBR'd lower, so it's gotta be able to come out quick enough.

I used the standard top loading Hahn and put in the 9mm bolt catch (not very hard to install but probably not as quick as you would like).  I like the top loaders better because they can't fall out and don't seem to move around as much.  I've tried a couple of different bottom loaders and had issues.

will the 9mm BHO work for 5.56 bolts?

Quoted: will the 9mm BHO work for 5.56 bolts?

shouldnt since the 9mm bho would have to be longer to reach the mag follower.





that being said though my 6450 has a std 5.56 bho but from the looks of it, it has an extension like an add on

So the bottom line is no BHO if I want to leave the bolt release alone?

Quoted: So the bottom line is no BHO if I want to leave the bolt release alone?

basically


you're wanting to build a sbr lower that does multiple things and usually those type products lack somewhere, good excuse to use cheaper uzi mags.

Quoted: So the bottom line is no BHO if I want to leave the bolt release alone?

You may have your cake and eat it too if you use Hahn bottom loading mag block.  With Colt mags, it has an actuator just to the right of the ejector which will work in conjunction with the 5.56 bolt latch to hold the bolt open.  I have successfully modified Promag mags to feed reliably and they will work the BHO has well.  If you don't care to do the modification, you'll have to be willing to spend $50.00+ per Colt mag for the privilege.
Click on the thumbnail for the full size pic. Note the actuator just to the left of the ejector in the pic.

Quoted: Quoted: So the bottom line is no BHO if I want to leave the bolt release alone? You may have your cake and eat it too if you use Hahn bottom loading mag block.  With Colt mags, it has an actuator just to the right of the ejector which will work in conjunction with the 5.56 bolt latch to hold the bolt open.  I have successfully modified Promag mags to feed reliably and they will work the BHO has well.  If you don't care to do the modification, you'll have to be willing to spend $50.00+ per Colt mag for the privilege. img419.imageshack.us/img419/7609/hahn9mmblock2dk.th.jpg Click on the thumbnail for the full size pic. Note the actuator just to the left of the ejector in the pic.

my 6450 uses something similar to that, looks different but functions the same way

I have an older RRA 2 pcs mag block and with pro-mags
and the 223 bolt release  the hold open works fine.

I guess it depends on the type of block you get.

I saw a brand new RRA bottom load block today and I must say, I was extremely disappointed with it.  It looked and felt very cheap and the feed ramp was pitiful looking.   When compared to my Hahn block, it was like comparing a CHEvette (RRA block) to a CORvette (Hahn block).

I am quite surprised there aren't more people complaining about feed and other problems with the RRA block.  I can't even believe they would work reliably based on the way they look.  If you have an opportunity, to compare blocks, you will realize that the Hahn blocks really are the best out there.


Bottom load can be swapped in and out in seconds and retains BHO w/Colt mags.

Top load can be swapped in and out in seconds while leaving the 5.56 bolt catch in, but does not retain BHO.  Can retain BHO w/Colt magsif you install a 9mm bolt catch (add 5-10 minutes to changeover time).

Dedicated top load retains BHO w/Colt mags, but count on about 5-10 minute changeover time since you have to remove the bolt catch to install/remove the block.

Still so confussing.

Will 9mm BHO work with 5.56 mags/bolts?

Quoted: Will 9mm BHO work with 5.56 mags/bolts?

No.

If you are planning on using one lower with both 9mm and 5.56 uppers and still retain the BHO feature for both platforms, bottom loading Hahn block is the Cadillac of them all.