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Posted: 12/14/2005 1:44:20 PM EDT
I am in the process of spec'ing out an SPR upper, and am leaning towards the PRI FF tube over the LaRue. Full length rails aren't particularly needed for the intended application....plinking and potential small game hunting.

Has anybody had any problems with the PRI?

Thanks.
Link Posted: 12/14/2005 2:49:39 PM EDT
Link Posted: 12/14/2005 3:30:45 PM EDT

Originally Posted By bigbore:
Daniel Defense





Link Posted: 12/14/2005 4:14:24 PM EDT
[Last Edit: 12/14/2005 4:16:18 PM EDT by murderman]
I have a DD 7.0 on my carbine, and like the heck out of it......maybe this should have been a three way question?

ETA: Ian, that looks alot like where I am heading; thanks for the pic.
Link Posted: 12/14/2005 4:46:25 PM EDT
[Last Edit: 12/14/2005 5:26:56 PM EDT by new-arguy]
Link Posted: 12/14/2005 5:00:57 PM EDT
Link Posted: 12/14/2005 5:24:14 PM EDT
Link Posted: 12/14/2005 5:31:04 PM EDT
Damn, you are quick with the edit...I was just fixin' to point out that the LT is shorter than the DD [not LT].

Nice post, and thanks...it is indeed all about "feel".
Link Posted: 12/14/2005 5:31:12 PM EDT
[Last Edit: 12/14/2005 5:34:40 PM EDT by bigbore]
Link Posted: 12/14/2005 5:33:39 PM EDT
Link Posted: 12/14/2005 5:35:23 PM EDT
Link Posted: 12/14/2005 5:48:25 PM EDT
How does one "glue" aluminum other than by welding? CF, I understand gluing.
Link Posted: 12/14/2005 5:50:07 PM EDT
There is no way in hell I am saying a thing.
Link Posted: 12/14/2005 6:13:19 PM EDT

Originally Posted By Gunzilla:
There is no way in hell I am saying a thing.



I think we should start a bet on how many pages this will go. Where is Grant?



Epoxy, it's not just for toilette seats anymore.

Link Posted: 12/14/2005 6:18:32 PM EDT

Originally Posted By murderman:
How does one "glue" aluminum other than by welding? CF, I understand gluing.



Epoxy. I trust epoxy. Hell, some of the planes we fly on are epoxied together.
Link Posted: 12/14/2005 6:58:36 PM EDT
[Last Edit: 12/15/2005 4:10:39 AM EDT by HKPDW]
Didn't you know ?

Some paper mache, black Krylon, a little Elmers...... and Bamm !



You're good to go

_______________________________________________________

"Plasma rifle in the 40 watt range"
Link Posted: 12/14/2005 7:04:22 PM EDT
Link Posted: 12/14/2005 8:32:40 PM EDT

Originally Posted By Boom:
Shit here we go. www.activistsandiego.org/wwwboard/images/smiles/lsvader.gif



Link Posted: 12/15/2005 6:07:47 AM EDT
Larue...Hands down
Link Posted: 12/15/2005 6:18:39 AM EDT

Originally Posted By HVMT556:
Larue...Hands down



Thanks for the very detailed explanation of why you think so.
Link Posted: 12/15/2005 6:28:36 AM EDT
[Last Edit: 12/15/2005 6:30:41 AM EDT by NewbHunter]
I like my glued together LT 9.0!

I've got plenty of glue sticks left over from art class in case it breaks, so no worries from me!

Seriously, I don't think you can go wrong with the DD or the LT. The DD is lighter. I don't think the fact that the LT is "glued" and the DD is welded should really even be an issue in deciding which one you buy. They're both plenty strong I'm sure. I haven't personally heard of either breaking (not that they haven't...everything breaks).
Link Posted: 12/15/2005 6:39:22 AM EDT
[Last Edit: 12/15/2005 6:40:59 AM EDT by C4iGrant]
Link Posted: 12/15/2005 6:39:36 AM EDT
Can someone point out where the LT rail is glued.
I am looking at a 12.0 and it looks like all one piece.
Link Posted: 12/15/2005 6:43:33 AM EDT

Originally Posted By alwaystryin:
Can someone point out where the LT rail is glued.
I am looking at a 12.0 and it looks like all one piece.




They are refereing to where the threads(Mating the barrel nut) meets the rails on the inside of the tube.
Link Posted: 12/15/2005 7:32:09 AM EDT
Thanks for the objective comparison feedback, Grant. I wasn't aware that the PRI rails weren't M1913 spec. It is probably not that big a deal in this particular case, since I don't use VFG's, but good to know nonetheless.

Decisions, decisions....

At least I know that I will be using LT for the bipod mount, gas block, and scope mount [assuming that the SPR's eventually get off backorder].

BTW, what kind of stock is that on the rifle in your pic?

Thanks.
Link Posted: 12/15/2005 7:37:21 AM EDT

Originally Posted By murderman:
Thanks for the objective comparison feedback, Grant. I wasn't aware that the PRI rails weren't M1913 spec. It is probably not that big a deal in this particular case, since I don't use VFG's, but good to know nonetheless.

Decisions, decisions....

At least I know that I will be using LT for the bipod mount, gas block, and scope mount [assuming that the SPR's eventually get off backorder].

BTW, what kind of stock is that on the rifle in your pic?

Thanks.



That's the new Magpul PRS stock. Sounds pretty sweet from what I've read. There's more info in the industry section in Magpul's forum.
Link Posted: 12/15/2005 7:50:24 AM EDT
Link Posted: 12/15/2005 8:40:11 AM EDT

Originally Posted By C4iGrant:
... they have the capability to follow the dead middle of the M1913 spec better than anyone.

C4




What exactly is the middle of the M1913 spec? Since the spec does not really specify variation what would the middle be?

Link Posted: 12/15/2005 9:04:19 AM EDT
[Last Edit: 12/15/2005 9:18:06 AM EDT by C4iGrant]
Link Posted: 12/15/2005 1:26:06 PM EDT
Can the rails be moved aroun on the PRI rail? Are the top rails to the correct height for a rail mounted front sight? Does anyone have a pic of the INSIDE of a PRI rail? Carbine hopefully? Need to see how far the rail screws stick in.
Link Posted: 12/15/2005 1:51:36 PM EDT

--------------------------------------------------------------------------------
Originally Posted By HVMT556:
Larue...Hands down
--------------------------------------------------------------------------------




Thanks for the very detailed explanation of why you think so.
....your welcome......{rolleyes}
Link Posted: 12/15/2005 3:06:38 PM EDT

Originally Posted By C4iGrant:

As far as Bipods go, the new TD one is about to be out (have one and love it). So you might want to rethink your options.

C4



I had been planning on a Harris with a LT mount.

I am not familiar with the TD unit; would you mind sharing any details...advantages/improvements? In particular, does it mount to a QD sling swivel; I try to maintain modularity whenever possible, and a QD swivel mount would allow use on my bolt guns.

Thanks.
Link Posted: 12/15/2005 4:06:03 PM EDT
Link Posted: 12/15/2005 4:12:41 PM EDT

Originally Posted By C4iGrant:

Originally Posted By ian187:

Originally Posted By C4iGrant:
... they have the capability to follow the dead middle of the M1913 spec better than anyone.

C4




What exactly is the middle of the M1913 spec? Since the spec does not really specify variation what would the middle be?




I asked Jeff C. of TD once what rails he has found that fit with their VG's the best. He said that LT's rails fit the best as they follow the middle of the 1913 spec. So apparently there is somewhat of a "zero" (neither on the - or + side) if you will and they seem to follow it the best from what I am told.


C4



So there is no "middle of the 1913 spec?"


Link Posted: 12/15/2005 5:30:16 PM EDT
[Last Edit: 12/15/2005 5:31:06 PM EDT by C4iGrant]
Link Posted: 12/15/2005 5:58:15 PM EDT
That bipod looks pretty nice, but I'll probably just settle for the Harris, since it will fit other weapons without rails equally well.

Thanks for the link.
Link Posted: 12/15/2005 6:03:12 PM EDT
Link Posted: 12/15/2005 6:22:58 PM EDT

Originally Posted By C4iGrant:

Originally Posted By ian187:

Originally Posted By C4iGrant:

Originally Posted By ian187:

Originally Posted By C4iGrant:
... they have the capability to follow the dead middle of the M1913 spec better than anyone.

C4




What exactly is the middle of the M1913 spec? Since the spec does not really specify variation what would the middle be?




I asked Jeff C. of TD once what rails he has found that fit with their VG's the best. He said that LT's rails fit the best as they follow the middle of the 1913 spec. So apparently there is somewhat of a "zero" (neither on the - or + side) if you will and they seem to follow it the best from what I am told.


C4



So there is no "middle of the 1913 spec?"





There probably is a middle ground, but am not a mechanical engineer and don't have a copy of the M1913 spec so I cannot say for certain.


C4



If the spec does not allow for any variation how can there be a "middle ground?"

Here is the spec:



Here is a link to the thread where the spec was posted.

Link Posted: 12/15/2005 6:31:42 PM EDT
I went with DD strictly for the weight savings. So far I haven't had any reasons to not like it. It's solid, fit and finish are excellent. I will try the Larue on my next build, simply because I'm a big Larue fan. Also like the sounds of the locking system.
Link Posted: 12/15/2005 6:43:50 PM EDT

Originally Posted By new-arguy:

Originally Posted By bigbore:
The PRi and LaRue are glued together. The DD and KAC are welded.



I stand corrected and apologize. I thought for sure I had read it was one peice, but cant say I know enought about it to feel confident about it. If it is indeed glued, I must say, I would probably rather have one that is welded!



I was suprised too:

www.ar15.com/forums/topic.html?b=3&f=12&t=258573

But whatever
Link Posted: 12/15/2005 7:29:38 PM EDT
.
Link Posted: 12/15/2005 8:09:04 PM EDT
Just FYI, those protective ceramic tiles on the space shuttle also glued and withstand temperatures as high as 2500-3000 degrees F.
Link Posted: 12/15/2005 8:18:36 PM EDT
[Last Edit: 12/15/2005 8:24:16 PM EDT by NickDrak]
LaRue 12.0


The DD will be a bit lighter, but I prefer the LaRue's steel barrel nut and the anti-spin device.
LaRue's customer service is the "best in the business", and DD's is not far behind, if not as good.
Link Posted: 12/15/2005 9:36:27 PM EDT
[Last Edit: 12/15/2005 9:39:26 PM EDT by JTinIN]
Went with the PRI over the LaRue for this build as was thinking for off hand was a little nicer (no rails to worry about / smaller diameter than with covers ?). The PRI works well, however, only using with a bipod, so the remaining rails are open at the moment. Additionally this PRI forearm was to have been a FBI mod that has the longer rail on the bottom to allow options on the location of the bipod.

With the existing holes, appears one can pick up extra short or long rails from PRI and add them to an existing forend, however, have not tried yet.

Next build will probably be a full rail system such at the LaRue or KAC FF (no one carries the DD in Indiana) and use the ACOG full time with the Colt A2 barrel (the PRI forend and Leupold scope then gets a semi match barrel for either Mk262 "5.56" or 6.8 SPC is ever end up with cases and realoading supplies).

Also one of these days need to get a photo of the upper with all the parts installed (Troy rear sight, charging handle, bolt, bipod) and on the M16A1 instead of the loaner AR15.


Link Posted: 12/16/2005 3:53:31 AM EDT
Link Posted: 12/16/2005 4:50:08 AM EDT

Originally Posted By C4iGrant:
That is not the only opinion. Here is what EOTech had to say on the subject. So YES there are deviances in the spec:


Please do a search for the MIL-STD-1913 rail Federal Publication from 3 Feb 1995. Near the end of the document are engineering schematics with the "precise" dimensions of the accessory or picatinny rail. You will notice that there is a range of allowable measurement for the thickness of the rail, height, and width. The range for the width of the rail alone allows for a possible difference in inches of over EIGHT TENTHS (0.8). That is not a small allowance when it comes to interfacing products. The height of the rail allows for a variance of .14 inches! The impact this has, is that if you produce something to fit a tight or specific tolerance (one exact measurement), you will only fit on the few rifles that meet that specification (less sales, less profit, less money to be spent on quality control...). Additionally, the amount of scrap that would be produced by rifle manufacturers due to not meeting that specification would make the industry completely not-profitable, and you'd be paying $4,000 for a new M4 as opposed to $900 (as an example).


C4



You have got to tell us who at EOTech said this!
Link Posted: 12/16/2005 5:02:54 AM EDT
Link Posted: 12/16/2005 5:34:12 AM EDT

Originally Posted By Gunzilla:


You have got to tell us who at EOTech said this!



I agree. There are some decimal points and a few zero's misplaced in that "info".

over .8 inches..????? I'd love to see the prints on a machined feature of that size that would allow almost an inch in variation (tolerance) because you wouldn't machine it you'd cut it with a torch or saw. The BASIC width of the rail itself is around .835 and we are supposed to believe that the width can vary as much as .800?



.835 +/- .400 ?
.835/.035 ?
.835 +.800/-.000 ?

Let's use some common sense here guys.
Link Posted: 12/16/2005 6:26:39 AM EDT
As was suspected, it was MORE BAD INFO and has been retracted.

From the above linked thread. Eotech thread


Originally Posted By DFinnegan:
ATTENTION EVERYONE.

My math was wrong, and to additionally show that I don't have an issue correcting or admitting mistakes; my interpretation of the math (and a limited explanation provided me) on the schematic was incorrect. I am not an engineer either, BTW.

The measurements are not .8" but smaller. However, there is still a variance in the possible dimensions which account for the cant issue. The measurement takes into account the use of geometric dimensioning and tolerance. It is more complex than a simple measurement but the variance still exists.

I apologize for posting incorrect numbers, but the point remains the same. Thanks for your patience.




More like 100 times smaller than .800 inches.
Link Posted: 12/16/2005 7:26:18 AM EDT
Link Posted: 12/16/2005 7:39:05 AM EDT

Originally Posted By C4iGrant:


If the spec does not allow for any variation how can there be a "middle ground?"

Here is the spec:

www.gunzilla.com/images/picshot.JPG

Here is a link to the thread where the spec was posted.




That is not the only opinion. Here is what EOTech had to say on the subject. So YES there are deviances in the spec:


Please do a search for the MIL-STD-1913 rail Federal Publication from 3 Feb 1995. Near the end of the document are engineering schematics with the "precise" dimensions of the accessory or picatinny rail. You will notice that there is a range of allowable measurement for the thickness of the rail, height, and width. The range for the width of the rail alone allows for a possible difference in inches of over EIGHT TENTHS (0.8). That is not a small allowance when it comes to interfacing products. The height of the rail allows for a variance of .14 inches! The impact this has, is that if you produce something to fit a tight or specific tolerance (one exact measurement), you will only fit on the few rifles that meet that specification (less sales, less profit, less money to be spent on quality control...). Additionally, the amount of scrap that would be produced by rifle manufacturers due to not meeting that specification would make the industry completely not-profitable, and you'd be paying $4,000 for a new M4 as opposed to $900 (as an example).




C4



I didn't know that the 1913 spec was an opinion. Would you please post 1913 spec prints showing differing opinions?

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