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Posted: 10/11/2004 12:04:36 AM EST
DO Colt LE models have sear blocks such as the MT6400C in the Lower?

I just thought about the possibility that there may be more differences than meets the eye!

Thanks
Link Posted: 10/11/2004 12:15:54 AM EST
Link Posted: 10/11/2004 2:52:03 AM EST
[Last Edit: 10/11/2004 2:52:25 AM EST by glockguy40]
Even if your LE receiver does have a sear block... Norrells provides machining services to remove your sear block should you so desire. Removing the sear block is legal... what you do after you remove the sear block is up to you. After the block is removed you can pay around 8-10 K for RDAIS, or, well.... get 10 yrs in prison if you're caught.

Norrell's site states:

M-16/AR-15 Modifications
* Removal of Colt auto sear block. Outside of receiver is unaltered. No refinishing required....$ 125.
* Conversion of small pin hole full auto trigger, hammer, and disconnector to larger Colt size. The holes in the
standard M-16 trigger, hammer and disconnector are opened up using a diamond hone to the larger Colt pin hole size.
Labor only, does not include price of parts....$ 100.

CHECK IT OUT HERE: Norrell's
Link Posted: 10/11/2004 3:24:42 AM EST
That area in my Colt LEO is way under machined, so you could call it a sear block..

I don't care, as I could never afford a RDIAS, and I would NEVER use a illegal one.. I like my ass just the way it is, UNTOUCHED!!!
Link Posted: 10/11/2004 4:51:02 AM EST
The Colt LE 6920 and MT6400 are identical inside with an unmachined portion including a cross web. I own both models and opened them up to compare. Really, the unmachined portion just makes the receiver that much stronger......as I am not interested in auto sears. Imagine trying to feed a fully auto gun? The UPS or Fed Ex truck would be making daily runs to your house. Ha!
Link Posted: 10/11/2004 6:07:00 AM EST

Originally Posted By MurdochsM4:
DO Colt LE models have sear blocks such as the MT6400C in the Lower?

I just thought about the possibility that there may be more differences than meets the eye!

Thanks



The MT6400C doesn't really have a "sear block" as such. As noted in a post above they just don't machine the area wide enough in the lower where the auto sear would be positioned. For that matter, nor do they drill the hole for the auto sear pin!

Most Dept's are aware of the folly of using FA for LE work and, believe it or not, many don't want the hassle of the paperwork anyway. I haven't been able to see any difference between the MT6400C and the LE lowers, other than the rollstamp.

The vast majority of commercial AR lowers from other manufacturers that I've seen are not machined wide enough in the auto sear area to accept a sear from a mil-spec select fire FCG. This is not exclusive to Colt. I think that where the confusion might be coming from is those people who continue to spread the falsehood that all Colt commercial lowers still come with that awful pinned-in sear block. They haven't made them that way in many years but some folks would prefer to perpetuate the myth.
Link Posted: 10/11/2004 7:08:22 PM EST
[Last Edit: 10/12/2004 3:52:43 AM EST by XM777]
Up until now I was under the impression that all Colt LEO Rifles had a sear block, either the pinned in type or the unmilled web. Funny thing, I popped open one of my 6721 LEO rifles tonight and was surprised to see that there was no block and the sear area was actually cut like an SP-1.

I am quite fond of the Colt 6721 and have collected a number of pre-ban and LEO rifles over the past ten years. Going through my safe and checking each, this is what I have found:

6721 Pre-Ban-

BD0001xx - Pinned in Block
BD0001xx - Pinned in Block

6721 LEO Rifles-

LBD0026xx - No Block/SP-1 Type Sear Area
LBD0045xx - No Block/SP-1 Type Sear Area

LBD0104xx - Unmilled Web Type Block

Others with Ser# > LBD0104xx - Unmilled Web Type Block

So it would appear that the original poster was correct in his statement " there may be more differences than meets the eye".

Pic of LBD0026xx showing SP-1 style sear area-



As a reference, this is the "Pinned" style block:



And the unmilled "Web" style block:

Link Posted: 10/12/2004 7:39:36 AM EST
Whether the bridge is present or the area directly above the saftey/selector is of the SP1 style is really a moot point if you are comparing the Colt commercial lowers to the LE variety. It looks to me like the LE semi-auto models have closely followed the commercial models in this respect, transitioning from the SP1 style through the pinned block and now the bridged style.

The last LE6920 that I looked at had the bridged lower. Other than the rollmark, this lower was identical to my MT6400C.

Just to make things clear, the area between the receiver walls located directly above the saftey/selector on the SP1 style lower (shown in the photo in the above post) measures approximately .430". This area on a select fire version is considerably wider since the automatic sear measures .680". In other words, you cannot drop in a COMPLETE select-fire FCG in any of these lowers (LE or commercial) without a trip to the milling machine, as if anybody would be stupid enough to do so .

There's no magic in the LE lowers!
Link Posted: 10/12/2004 8:47:13 AM EST
[Last Edit: 10/12/2004 9:12:34 AM EST by XM777]

Originally Posted By Str8shot:
It looks to me like the LE semi-auto models have closely followed the commercial models in this respect, transitioning from the SP1 style through the pinned block and now the bridged style.



And that is what I had always thought but if you read my post more carefully you can see that this is not the case. The first 6721's off the line in 1994 were manufactured with a "pinned" type block. Then around Ser# 2600-4500 Colt dropped the block altogether and mfg. these with an SP-1 style sear area. Then, by #10,000 they had gone back to the block and were mfg'ing with the "web" style.

No, there is no magic. I was just pointing this out as RDIAS owners are looking for cheap and reliable hosts for their sear that do not require milling work done to the lower. Almost all new mfg. lowers will require some milling work because of the "high shelfs" or methods employed to block the sear area. An LEO rifle with a SP-1 type sear area will allow the RDIAS to drop right in.
Link Posted: 10/12/2004 10:08:07 AM EST
To clarify, do the LE models have the standard diameter fire control pin holes or the enlarged ones?
Link Posted: 10/12/2004 2:49:31 PM EST

I think that it is safe to say that all Colt LEO Rifles are of the large pin type, at least every one I have ever seen.
Link Posted: 10/12/2004 3:32:41 PM EST
Fascinating thread! Thanks for posting the pictures, too; now I know what a sear block looks like.
Link Posted: 10/12/2004 8:45:10 PM EST
Link Posted: 10/13/2004 7:00:49 AM EST

Originally Posted By XM777:

Originally Posted By Str8shot:
It looks to me like the LE semi-auto models have closely followed the commercial models in this respect, transitioning from the SP1 style through the pinned block and now the bridged style.



And that is what I had always thought but if you read my post more carefully you can see that this is not the case. The first 6721's off the line in 1994 were manufactured with a "pinned" type block. Then around Ser# 2600-4500 Colt dropped the block altogether and mfg. these with an SP-1 style sear area. Then, by #10,000 they had gone back to the block and were mfg'ing with the "web" style.

No, there is no magic. I was just pointing this out as RDIAS owners are looking for cheap and reliable hosts for their sear that do not require milling work done to the lower. Almost all new mfg. lowers will require some milling work because of the "high shelfs" or methods employed to block the sear area. An LEO rifle with a SP-1 type sear area will allow the RDIAS to drop right in.



I see what you're saying .

The point that I was trying to make is that it appears that some folks are under the impression that the LE lower is identical to the military version in all respects (except for the rollstamping) and somehow "superior" or more desireable than the MT6400C lower. The LE versions are not 'mil-spec' either. Besides, I think that some people are getting carried away with this 'mil-spec' business anyway .

I didn't address the desirability of the SP1 style sear area for RDIAS installation because this is a gray area for most shooters and, IMHO, is not really applicable to this thread. Also, I have encountered some RDIAS's that still required milling of the SP1's sear area due to the fact that the RDIAS was too wide to fit that space.
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