PDA

View Full Version : Another 9mm AR question


D53
11-06-2009, 3:57 PM
Ok so I know I have started a post about the mags, but this question is about ramping the bolt. So i know that when doing a 9mm build you need to use a 9mm hammer in a AR. I have the Rainer one, but I have also read that you can use the DPMS hammer and it will work for both 9mm and .223 bolts, so if I want to swap at the range all I have to do is remove the mag block and the upper ( easy swaps on the fly).
I have also read that you can use a .223 hammer but you will need to ramp the bolt. I am planning on buying a RRA 9mm upper ( which will come with the BCG already),

For all the guys out there running .223 hammers in their 9mm ARs with a ramped 9mm bolt, how is it holding up, please include round counts. I have also read about the trigger pins walking out and oblonging, but I purchased the KNS anti rotation pins and already have them installed which seems to be the cure for the pin problems.

on a side note, I have a killer headache so I apologies a head of time if while reading this it gets confusing with all the run on sentences.

edit: I know that if I wanted to swap uppers at the range I would have to swap out the buffer also.

NavDoc
11-06-2009, 5:42 PM
FWIW,
1) The rounded DPMS hammer needs to be used with a ramped 9mm bolt to lengthen the hammer reset distance and reduce wear. It will also work with a non-ramped bolt, but some fear it is hard on the pins. You cannot use a standard "notch faced" AR hammer, regardless of bolt ramping, as the notch can get caught under the rear of the bolt and lock up your gun.

2) You can run a 9mm hammer in a .223 upper without issue. Do not combine a 9mm hammer with ramped bolt, as you will have failures to rest the hammer.

3) You can use Spikes Tactical ST-T2 buffer in both .223 and 9mm, eliminating a buffer swap.

4) What pin problems? If the gun is set up properly, what problems do you anticipate? I've never been a fan of KNS pins, as I have never seen the issue they supposedly solve. YMMV

NavDoc
11-06-2009, 5:46 PM
Oh, I run an RRA upper and bolt with a 9mm hammer, Hahn dedicated block, and RRA buffer. I use only C-products mags. Finished the build a couple months ago. I'm at over 1000 rds without a single issue.

supermario
11-06-2009, 10:40 PM
Or you could use a CMMG 9mm ramped BCG and then you can use any basic 5.56 lower. Then add the Spikes Tactical ST-T2 buffer and you can then swap on the fly as you want. I want to do the same thing also. I am just trying to figure out what magblock would be the easiest to swap out but also feed reliable.

supermario
11-06-2009, 10:41 PM
FWIW,
1) The rounded DPMS hammer needs to be used with a ramped 9mm bolt to lengthen the hammer reset distance and reduce wear. It will also work with a non-ramped bolt, but some fear it is hard on the pins. You cannot use a standard "notch faced" AR hammer, regardless of bolt ramping, as the notch can get caught under the rear of the bolt and lock up your gun.

2) You can run a 9mm hammer in a .223 upper without issue. Do not combine a 9mm hammer with ramped bolt, as you will have failures to rest the hammer.

3) You can use Spikes Tactical ST-T2 buffer in both .223 and 9mm, eliminating a buffer swap.

4) What pin problems? If the gun is set up properly, what problems do you anticipate? I've never been a fan of KNS pins, as I have never seen the issue they supposedly solve. YMMV

Is this buffer heavier than a 5.56 H buffer? thanks

Josh3239
11-06-2009, 10:42 PM
ST= Spike's Tactical

Standard CMT carbine buffer - 2.9 oz.

CMT H buffer - 3.8 oz.

CMT H2 buffer - 4.1 oz.

Armalite H3 buffer - 4.7 oz.

RRA 9mm buffer - 5.5 oz.

ST-X SS 9mm buffer - 6.0 oz.

ST-SST - 7.0 oz.

ST-9X SS Extended 9mm buffer - 8.5 oz.

NavDoc
11-07-2009, 7:32 AM
The ST-T2 weighs 4.3 oz.