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Posted: 1/21/2006 3:03:11 PM EDT
Do the RRA barrel's have F marked Front sight bases? And does anyone know what type of metal they are made from? Thanks
Link Posted: 1/21/2006 3:09:10 PM EDT
4140
Link Posted: 1/21/2006 3:18:01 PM EDT
Standard barrels are made of 4140 or stainless steel, your choice... They use the standard FSB, not the military 'F' stamped ones...
Link Posted: 2/5/2006 4:56:35 AM EDT
If we bought a RRA upper assembly (ready to rock with a stocked lower) and it has the A4 upper, do we need a taller front post?

How does RRA deal with using the standard FSB with a DCH/A4 upper? "F" stamped FSB, custom FSB, or a taller front post?
Link Posted: 2/5/2006 5:33:15 AM EDT

Originally Posted By theshootersden:
Standard barrels are made of 4140 or stainless steel, your choice... They use the standard FSB, not the military 'F' stamped ones...


The use of an F FSB is an issue only on flat top rifles. A2s require a std height FSB, unless you want to screw the post down several turns.
Link Posted: 2/5/2006 5:37:06 AM EDT

Originally Posted By SWO_daddy:

Originally Posted By theshootersden:
Standard barrels are made of 4140 or stainless steel, your choice... They use the standard FSB, not the military 'F' stamped ones...


The use of an F FSB is an issue only on flat top rifles. A2s require a std height FSB, unless you want to screw the post down several turns.



So what happens when you buy a RRA assembled upper with the A2 FSB and A4/flat top upper?
Do you get a F FSB or a taller front post?

I bought a Bushmaster w/ the A2 FSB and used it on a flat top. My front post was almost coming off the FSB and I was still shooting high.
Link Posted: 2/5/2006 5:38:58 AM EDT

Originally Posted By metroplex:
So what happens when you buy a RRA assembled upper with the A2 FSB and A4/flat top upper?
Do you get a F FSB or a taller front post?


I couldn't tell you because I don't have a flat top. But somehow lots of people with them get along fine.
Link Posted: 2/5/2006 6:29:26 AM EDT
[Last Edit: 2/5/2006 6:31:53 AM EDT by theshootersden]

Originally Posted By metroplex:

Originally Posted By SWO_daddy:

Originally Posted By theshootersden:
Standard barrels are made of 4140 or stainless steel, your choice... They use the standard FSB, not the military 'F' stamped ones...


The use of an F FSB is an issue only on flat top rifles. A2s require a std height FSB, unless you want to screw the post down several turns.



So what happens when you buy a RRA assembled upper with the A2 FSB and A4/flat top upper?
Do you get a F FSB or a taller front post?

I bought a Bushmaster w/ the A2 FSB and used it on a flat top. My front post was almost coming off the FSB and I was still shooting high.



RRA does not use the 'F' marked FSB, period... Whether you buy their carbine or rifle, with or with out a flat top receiver, you will receive a gun that has a regular original style A2 FSB...

Companies like RRA and Bushmaster, when building a gun using a flat top receiver and A2 FSB will compensate the FSB difference by using a detachable carry handle that is machined differently to match the A2 FSB height... There are two types of carry handles, commercial and mil-spec, or as some people refer to as Bushmaster or COLT... COLT is Mil-spec and the taller of the two...

When a person has to raise the FSP to extremes, it is usually due to the rear sight being to tall... There are BUIS on the market that are A2 height and others that are flat top height...
Link Posted: 2/5/2006 6:34:00 AM EDT

Originally Posted By metroplex:

I bought a Bushmaster w/ the A2 FSB and used it on a flat top. My front post was almost coming off the FSB and I was still shooting high.



The question is, what rear site were you using?
Link Posted: 2/5/2006 7:22:13 AM EDT

Originally Posted By Stickman:

Originally Posted By metroplex:

I bought a Bushmaster w/ the A2 FSB and used it on a flat top. My front post was almost coming off the FSB and I was still shooting high.



The question is, what rear site were you using?



A non-Colt DCH. I am now using a taller front post for that rifle.

So if I purchase the RRA DCH, it will be of the correct height when used with the RRA A2 FSB?
Link Posted: 2/5/2006 7:34:59 AM EDT
The question is, where is the DCH sight height measured at, and what height do I need for use with standard A2 FSBs?

Thanks!
Link Posted: 2/5/2006 7:44:37 AM EDT
[Last Edit: 2/5/2006 7:59:37 AM EDT by theshootersden]
You can measure it to find out if it is a MilSpec or commercial DCH, that will give you an idea of where your at... You could use the specs listed below to get an idea of what type DCH you have...

Commercial DCH: bottom of DCH to center of windage screw = 1.006"
MilSpec DCH: bottom of DCH to center of windage screw = 1.051"


Commercial DCH: bottom of DCH to aperture (Bottom inside of large hole) = 1.247"
MilSpec DCH: bottom of DCH to aperture (Bottom inside of large hole) = 1.292"


Which ever you come closest to when comparing your measurements to the above specs should tell all...

ETA: These measurements were taken off of two Cardinal forge carry handles, one being commercial off of a bushmaster and the other one being mil-spec off of a COLT...
Link Posted: 2/5/2006 7:52:34 AM EDT
[Last Edit: 2/5/2006 7:55:54 AM EDT by theshootersden]

Originally Posted By metroplex:
what height do I need for use with standard A2 FSBs?

Thanks!



'A2' FSB = shorter rear sight (commercial)...

'F' FSB = taller rear sight (mil-spec)...
Link Posted: 2/5/2006 2:05:51 PM EDT
I measured mine. It's 1.10" from bottom of DCH to center of windage screw.
It's slightly over your mil-spec specs... it's a Leapers/Tapco DCH FWIW. They're now $69 (WTF, over) so I'll be ordering a real DCH from the EE.
Link Posted: 2/5/2006 3:14:04 PM EDT
I have an RRA flat top with an Eagle carry handle and it works fine. Front sight post is about the same as on my A2.

Cheers,

Phil








Link Posted: 2/10/2006 9:44:01 AM EDT
The first measurement is a bit hard to take since my caliper can't exactlyfigureout the center of the windage adjustment screw.

However, the second measurement shows about 2.045"-2.050". It seems like it is a commercial-spec DCH?

With the rear sight fully seated, the top part does not protrude above the carry handle.

My leapers DCH, OTOH, measures like a "mil-spec" and with the rear sight fully seated, it is dead even with the carry handle.
Link Posted: 2/10/2006 11:04:55 AM EDT

Originally Posted By metroplex:
The first measurement is a bit hard to take since my caliper can't exactlyfigureout the center of the windage adjustment screw.

However, the second measurement shows about 2.045"-2.050". It seems like it is a commercial-spec DCH?

With the rear sight fully seated, the top part does not protrude above the carry handle.

My leapers DCH, OTOH, measures like a "mil-spec" and with the rear sight fully seated, it is dead even with the carry handle.



There are at least two different size rear sight assemblies used too...
Link Posted: 2/10/2006 12:25:58 PM EDT
[Last Edit: 2/10/2006 12:26:19 PM EDT by metroplex]
I didn't bother to precisely measure both rear sights, but from a cursory eval, the rear sights appear to be the same (with the obvious machining/casting/forging differences), but the Leapers puts the rear sight base higher than the DPMS. I suspect Leapers copied the Colt MIL-SPEC handle, while DPMS's "mil-spec" handle is based on a commercial spec handle.

Overall the DPMS model isn't bad at all. I've already set the rear elevation wheel to LTC Santos' IBZ setup.

6/3 -4 clicks (because it takes 6 clicks between 6/3 and 4).
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