Thinking about a 9mm AR upper...

[Perplexed]

Nice can, and yes, 9mm uppers are expensive. Soooo... anyone know about the 9mm hammer and buffer?

 

[338Shooter]

i would run a standard rounded hammer and get a ramped bolt. The RRA 9mm buffer and wolf extra power spring works good at slowing my gun down. If you run a regular buffer and spring the action cycles way too fast and the gun will beat itself up. If you try to run suppressed it will be louder with the lighter buffers and springs. You'll get more port noise as the bolt opens sooner.

 

[Perplexed]

i would run a standard rounded hammer and get a ramped bolt. The RRA 9mm buffer and wolf extra power spring works good at slowing my gun down. If you run a regular buffer and spring the action cycles way too fast and the gun will beat itself up. If you try to run suppressed it will be louder with the lighter buffers and springs. You'll get more port noise as the bolt opens sooner.

Thanks, Dustin. I assume a complete RRA 9mm upper would include the ramped bolt, or would I have to order this separately? Their web site says their complete uppers include a bolt carrier group and charging handle assembly, but it doesn't mention the type of bolt. Also, their site mentions two types of CAR buffers - standard and heavy. I assume the heavy buffer is what I'd want with a 9mm upper?

 

[NikatKimber]

If you want a rail that covers the front gas block just remove the gas block. 9mm ARs don't use a gas system.

I don't know about the spikes, but the Hahn mag blocks are the best. Just pick the one that suits your needs the best. I'd go with the top loading dedicated block if you're not gonna SBR. No real reason to run multiple uppers on a regular lower. If you SBR, then I like the bottom loading block so you can have the bolt hold open and still easily switch calibers.

Wouldn't the top loading block be nearly as easy to use if swapping uppers anyways? Since you have to have the upper off already? Or am I missing something?

 

[338Shooter]

There are two types of top loading block. One that drops in for quick swaps but doesn't allow you to use a standard AR15 bolt catch and bolt hold open. You can use the 9mm bolt catch that is very prone to breaking, but this renders it only good for 9mm defeating the purpose of having the fast swap top loading model. If you don't care about bolt hold open, and want fast caliber swaps, this is the way to go I guess.

The other goes under the bolt catch and allows the use of a standard bolt catch and bolt hold open feature. But, it requires the removal of the bolt catch roll pin to remove for caliber swaps. If you want a dedicated 9mm and have no plans on changing calibers I'd run this one (I'd probably really run the bottom loading block for this one too).

The bottom block is the only one that is a quick swap and still gives you bolt hold open with a standard bolt catch. If you want quick and easy caliber swaps and bolt hold open this is the way to go.

9mm bolt catch:
The long tab that the mag engages breaks off easily.
[Broken External Image]

 

[338Shooter]

Thanks, Dustin. I assume a complete RRA 9mm upper would include the ramped bolt, or would I have to order this separately? Their web site says their complete uppers include a bolt carrier group and charging handle assembly, but it doesn't mention the type of bolt. Also, their site mentions two types of CAR buffers - standard and heavy. I assume the heavy buffer is what I'd want with a 9mm upper?

RRA bolts don't come ramped. CMMG makes a ramped 9mm bolt. I think spikes does too. If you get one, you can sell your bolt on ARFcom for about $50 less than a new ramped CMMG bolt. I forgot, I talked to Olyeller and he will ramp bolts. I think he quoted me $35 to do mine. I still need to take it over to him.

No you actually want their 9mm buffer.

http://adcofirearms.com/acc/productLine_.cfm?brand=Rock River&product_category=Buttstocks

http://www.rockriverarms.com/index.cfm?fuseaction=category.display&category_id=244

Also, make sure any upper you get the barrel is 1:10" twist. Some of them are 1:15" and won't stabilize 147gr and heavier ammo reliably. Very important if you want to suppress.

 

[NikatKimber]

I checked spikes just now, they don't list a 9mm bolt separate, but their upper comes with the CMMG ramped bolt.

Thanks for the explanation on the mag block, I figured there had to be a catch to it somewhere.

 

[NikatKimber]

Dustin, you use the RRA buffer, which is 5.6oz. What would you think about using an even heavier buffer? Like the Hahn or Spikes 9mm buffers that are about 8+ oz?

 

[338Shooter]

I wanted one of the spikes extra heavy buffers, but I didn't want to spend the money to try it. After I shot it on GTG's m16 lower I don't think I want the cyclical rate any lower.

 

[Perplexed]

Dustin, you use the RRA buffer, which is 5.6oz. What would you think about using an even heavier buffer? Like the Hahn or Spikes 9mm buffers that are about 8+ oz?

Do you know anything about Spike's ST-T2 heavy buffer (4.3 oz) with the 9mm buffer spacer:

http://www.spikestactical.com/new/z/stt2-heavy-buffer-st9bs-combo-p-235.html