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Posted: 6/8/2006 11:09:22 AM EDT
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I am preparing to assemble a SBR lower, and eventually want to run 3 calibers - 5.56mm, Colt-style 9mm, and .22lr. I am sure I will need a 9mm hammer for this, but which one? Is anyone else running a multicaliber setup like this? I am hoping to avoid swapping hammers every time I want to change calibers. Any tips and advice you can provide will be appreciated. Thanks. |
My 9mm bolt is not ramped..... it's fine (though I'm using a DPMS compatible hammer...). All one needs is the "correct" hammer that will work w/ both 223 and 9mm. Ramping is........ not required, but can help.... |
so will an RRA 9mm hammer work with 5.56? |
Yes. That's what I did. About bolt ramping From M60joe's website....
You don't have to ramp your bolt, but it is the general consensus that if you don't (and you use a regular hammer) you will eventually egg out your receiver hammer pin holes. Also, if you use the 9mm hammer, you will not be able to use some other calibers because the notch in the 9mm hammer will prevent the bolt from returning to battery and it will remain jammed in the buffer tube. This happened to me when I was experimenting and I had to remove the buffer tube to get the mechanism free. Since I have had my RRA 9mm bolt ramped, I have installed a DPMS hammer and I can shoot any caliber I want without problems. If you don't want to go through the expense of ramping a bolt, you can do two things, use the 9mm hammer and change it out when you want to shoot another caliber, or use a DPMS hammer and not worry about the damage to your holes. The damage will occur slowly over a long period of time if you are only shooting semi-auto. However if you have a SBR registered receiver or a machine gun, I would not only ramp the bolt, but install a KNS pin set. The easiest thing to do is install a DPMS hammer and shell out the $70 to get your bolt ramped 
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I thought I did it the easy way. A six-pack, a Dremel tool, and a warm spring afternoon on the deck. Yes, a conventional 5.56 hammer can be castrated with a Dremel, and work for both 5.56 and 9. It is also possible to remove too much metal, and have a hammer which functions with neither. Ask me how I know! 
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see above
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according to: ar15.com/forums/topic.html?b=2&f=38&t=151118 his 9mm hammer worked with 5.56?? |
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What type of carrier were you using? Or doesn't that make any difference? The neutered Colt were there is no bottom of the ring????? I'm not trying to be difficult, just making sure they don't work in all instances, or maybe it was just with your particular setup. I have a 9mm gun set up, but am abit afraid to try it with some others of my 5.56 uppers because I don't want the damn thing to lock up on me or something. Thanks for the info The above reply came in while I was typing mine..... This is what I mean, if it works for some and not others, it can not be a simple "It doesn't work for 5.56"....... |
| I have the RRA notched 9mm hammer in my Bushy and I had tested it extensively with both my RRA 9mm upper and my stock 223 upper as well and it has worked 100% everytime. I would like to point out though, that the bolt carrier that I'm using for the 223 is a chromed Smith Ent. unit that I've had for some time and the area under the firing pin base is fully supported with a small ramp just as on an M-16 carrier. The rear of the carrier is AR-15 profile so at the time I bought it, it was a legal alternative to a full M-16 carrier. Most stock AR-15 carriers don't have this extra support and this may be why the 9mm hammers will not work with some 223 uppers. I hope this is some help to you HK DUDE. |
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An "AR-15" hammer as sold my most manufacturers except DPMS with the notch at the top front for catching the firing pin will catch on an unramped 9mm bolt and lock it up. Thus you need to run a hammer w/o that notch, such as an M16 hammer, or the DPMS which is like the neutered M16, or a 9mm hammer. If you do that you don't need to ramp the bolt, but you might want to to reduce the abuse to the hammer pin. If you ramp the bolt you can use the "AR-15" hammer because the ramping removes the part that catches and locks it up. A ramped bolt with 9mm hammer might not re-cock because it might not push the hammer down far enough. That may only be an issue with full-auto because it has to go back farther to catch the auto-sear than to catch the disconnector/semi-sear. Looking at the 9mm hammer I don't see why it wouldn't work with the 5.56 carrier (or .22LR), unless it has the same issue with that that it has with the ramped 9mm bolts--not far enough down to catch. And again, it might be an issue with the auto-sear and not the disconnector/semi-sear. Older-style "AR-15" carriers with exposed firing pin vs. newer "enhanced" carriers might make a difference too. The guy who said his BM 5.56 worked with 9mm hammer may have had the newer carrier with shrouded FP. I suspect the older type won't re-cock a 9mm hammer. |
| Correct Mike L. My bolt carrier is what they call an "enhanced" version nowadays with the firing pin base shroud. It actually is nothing new. I bought this unit for my Bushy back in 1993 and they were offered in both hard chrome and parkerized versions. I paid somewhere around 140.00 for the complete unit which now would only buy you the carrier alone. I thought it was a better alternative than the stock unit and had no idea at the time about how well it would work in a 9mm conversion today. |
| Looking at my last sentence in my post above I meant to say that I had no idea back then that my enhanced bolt would work so well today firing my 5.56 upper while using the RRA 9mm hammer in my lower receiver. Just thought I would say that to avoid any confusion. |
| I bought the Bushmaster as a stripped receiver in '92, not as a complete rifle. I then purchased the bolt carrier group the following year(yes I waited that long) and actually bought an A-1 upper for it in the beginning and switched to a Bushmaster M4A3 upper in 2000. I kept the bolt carrier group and have it in the rifle to this day. At that time in '93 the enhanced carriers didn't come as a standard item with the factory uppers. |
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