R6600

Serial numbers picks up were the SP1 left off, produced 1985-1990.  Features are as such:

CM upper forge code, big hole slab side lower, no sear block, no auto sear cut in upper, small pin hammer/trigger pins, modern small forward assist, SP1 bolt carrier, bolt marked MPC with a space between the M and the P, blue extractor buffer, AR-15 A2 HBAR SPORTER, lower roll marked COLT’S FIREARM DIVISION, barrel stamped C MP 5.56 NATO 1/7 HBAR, peel washer, A2 furniture, bayo lug

Not going to list features of each example, unless they are different then indicated above.  The Delta HBAR, R6600DH was introduced in 1987.

215677 appeared in the May 1986 issue of American Rifleman
22151X
2293XX made in June of 1988
233978
245018
249256 this is a Delta H-BAR, as in R6600DH, white label box

R6601

1990

In general these have the following features:

CM or CMB upper forge code, modern small forward assist, roll marked SPORTER MATCH HBAR, SPORTER bolt carrier, bolt marked MPC with a space between the M and the P, blue extractor buffer,  barrel stamped C MP 5.56 NATO 1/7 HBAR, peel washer, A2 furniture, no bayo lug

247401 CM upper forge code, big hole slab side lower, no sear block, no auto sear cut in upper, small pin hammer/trigger pins, modern small forward assist, SP1 bolt carrier, bolt marked MPC with a space between the M and the P, blue extractor buffer, AR-15 A2 HBAR SPORTER, lower roll marked COLT’S FIREARM DIVISION, barrel stamped C MP 5.56 NATO 1/7 HBAR, peel washer, A2 furniture, this is a R6600K, no bayonet lug, with a .22 conversion kit, built in 1990

2497XX CM upper forge code, big pin slab lower with no sear block, modern small forward assist, roll marked SPORTER MATCH HBAR, SPORTER bolt carrier, bolt marked MPC with a space between the M and the P, blue extractor buffer,  barrel stamped C MP 5.56 NATO 1/7 HBAR, peel washer, A2 furniture, no bayo lug, small hammer/trigger pin holes, roll marked COLT'S MFG, blue label 6601 box, purchased in June of 1990

MH 001001 A2 lower, big hole pivot pin, no sear block

MH 006600 and up have large trigger/hammer pins

MH 007657 slab lower with no sear block, CM upper, roll marked COLT'S MFG, 1990 manufacture

MH 010063 slab lower with no sear block, roll marked COLT'S MFG

1991

MH 013495 A2 lower with mag fense, big hole pivot pin, sear block pinned on both side, CM upper, made in 1991

MH 029XXX slab side lower, big pivot pin, sear block appears to be pinned in on both sides (with two on the left), looks like it has a SPII upper on it

MH 0295XX slab side lower, big pivot pin, sear block appears to be pinned in on both sides (with two on the left), made in 1991

MH 031037 CM upper forge code, slab side lower, big pivot pin, sear block appears to be pinned in on both sides, roll marked COLT'S MFG

1992

MH 04242X A2 lower with mag fense, big hole pivot pin, sear block pinned on right side, roll marked, COLT'S MFG

1993-1994

MH 0573XX CM upper forge code, mag fenced lower, small pivot pin hole, weep hole drilled, marked COLT'S MFG CO. INC., sear block pinned in on right side

MH 0649XX mag fenced lower, small pivot pin hole, weep hole drilled, bolt marked MPC and carrier has a "C" , was made in Sept. 1993 according to Colt

MH 074104 CMB upper forge code, mag fenced lower, small pivot pin hole, weep hole drilled?, marked COLT'S MFG CO. INC., sear block pinned in on right side

MH 089612 mag fenced lower, small pivot pin hole, weep hole not drilled, marked COLT'S MFG CO. INC., sear block pinned in on both sides

MH 09XXXX CMB upper forge code  mag fenced lower, small pivot pin hole, weep hole not drilled, marked COLT'S MFG CO. INC., sear block pinned in on both sides, Vietnam Tribute engraved rifle

MT6601

1994-

Same as R6601 less flash hider, and now roll marked MATCH TARGET MATCH HBAR

CMH 001002

CMH 00177X Gray finish, CMB upper forge code, mag fenced lower, small pivot pin hole, weep hole not drilled, marked COLT'S MFG CO. INC., sear block pinned in on both sides

CMH 003084 purchased this as a complete lower assy from CDNN in 05/08/96 for $289.99, don't recall the features

CMH 026653 appears to be black, small pivot pin hole, weep hole not drilled?, marked COLT'S MFG CO. INC., no pinned in sear block

CMH 031231 black finish, small pivot pin hole, weep hole not drilled, marked COLT'S MFG CO. INC., no pinned in sear block, purchased this as a stripped lower from R-GUNS,

CMH 035XXX black finish, small pivot pin hole, marked COLT'S MFG CO. INC, 04/00

CMH 041298 black finish, small pivot pin hole, weep hole not drilled, marked COLT'S MFG CO. INC., no pinned in sear block, this one has a brake making it a MT6601C

1995- LEO AR-15 HBAR AR6601

These are the same as the MT6601 but have a flash hider and are roll marked AR-15 MATCH HBAR

LMH 0015XX black finish, C and A upper forge code, small pivot pin hole, weep hole not drilled, marked COLT'S MFG CO. INC., no pinned in sear block,

LHM 001XXX  black finish, no pinned in sear black, marked COLT'S MFG CO. INC, suspected 2001 production

And then there's my oddball. First two pics in the thread.

I bought in NIB in June 1990. Straight SP1 lower receiver in all manners, with R6601 markings.

I have not checked the date of manufacture on this on yet  maybe 2001

Quoted: And then there's my oddball. First two pics in the thread. I bought in NIB in June 1990. Straight SP1 lower receiver in all manners, with R6601 markings.

Missed that thread, that will keep me busy for a bit.  Added yours like this:

2497XX CM upper forge code?, slab lower with no sear block, modern small forward assist, roll marked SPORTER MATCH HBAR, SPORTER bolt carrier, bolt marked MPC with a space between the M and the P, blue extractor buffer,  barrel stamped C MP 5.56 NATO 1/7 HBAR, peel washer, A2 furniture, no bayo lug, large hammer/trigger pin holes, blue label 6601 box, purchased in June of 1990

That look right?

Quoted: I have not checked the date of manufacture on this on yet  maybe 2001 img.photobucket.com/albums/v651/PhotoTWB/DSCN0130web.jpg

That is a rare one, stuck it in with the other.

Ekie,

Here is your list with the appropriate corrections:

2497XX - correct, with SP prefix
CM upper forge code - correct
slab lower with no sear block - correct
modern small forward assist - correct
roll marked SPORTER MATCH HBAR - correct
SPORTER bolt carrier - correct (assuming you mean the "C" cut rear of the carrier)
bolt marked MPC with a space between the M and the P - No. The letters MPC are evenly spaced
blue extractor buffer - correct
barrel stamped C MP 5.56 NATO 1/7 HBAR - correct
peel washer - correct
A2 furniture - correct
no bayo lug -correct
large hammer/trigger pin holes - No. Standard, small sized hammer and trigger pins
blue label 6601 box - correct
purchased in June of 1990 - correct

It also has the large hole pivot pin.

Hopes this helps you out.


You know what they say about confusion?

It just means you're learning something.

Unless you're Sgt. Bilko. He says there's money to be made in confusion.

Quoted: Ekie, Here is your list with the appropriate corrections: 2497XX - correct, with SP prefix CM upper forge code - correct slab lower with no sear block - correct modern small forward assist - correct roll marked SPORTER MATCH HBAR - correct SPORTER bolt carrier - correct (assuming you mean the "C" cut rear of the carrier) bolt marked MPC with a space between the M and the P - No. The letters MPC are evenly spaced blue extractor buffer - correct barrel stamped C MP 5.56 NATO 1/7 HBAR - correct peel washer - correct A2 furniture - correct no bayo lug -correct large hammer/trigger pin holes - No. Standard, small sized hammer and trigger pins blue label 6601 box - correct purchased in June of 1990 - correct It also has the large hole pivot pin. Hopes this helps you out. You know what they say about confusion? It just means you're learning something. Unless you're Sgt. Bilko. He says there's money to be made in confusion.

Corrections made, due to the small hammer/trigger pins I moved it back in the time line.

Have not been typing out the SP prefix, did not do it on the SP1 data base, and don't feel like typing all those SP's now.  Call me lazy, ha.

The 1970's Colt bolt were marked MPC with the M and the P run together.  To differentiate later bolts like yours I add the bit about there being a space the M and P.  Make sense?

And thanks for the info.

That would be a lot of SP's wouldnt' it?

The 1970's Colt bolt were marked MPC with the M and the P run together. To differentiate later bolts like yours I add the bit about there being a space the M and P. Make sense?

That's right. The one leg of the M was shared with the leg of the P, wasn't it? I think I've seen pictures like that. Yes, mine is not like that.

Quoted: That would be a lot of SP's wouldnt' it?

Yes, there are quite a few SP1's in the data base, alot of "SP" typing to do.

www.ar15.com/forums/topic.html?b=3&f=118&t=264305

Quoted: That's right. The one leg of the M was shared with the leg of the P, wasn't it? I think I've seen pictures like that. Yes, mine is not like that.

You got it, that is one way to date a bolt.  One of the reasons for the data bases, to establish such variation.

Great info Ekie!!!!  

Here are a couple of rollmarks for refrence

Quoted: Here are a couple of rollmarks for refrence images.snapfish.com/346545%3A%3C8%7Ffp63%3Dot%3E232%3C%3D363%3D437%3DXROQDF%3E2323%3B57%3C%3B6%3B39ot1lsi images.snapfish.com/346545%3A%3C8%7Ffp45%3Dot%3E232%3C%3D363%3D437%3DXROQDF%3E2323%3B57%3C%3B6%3A%3C9ot1lsi

Got em, thanks.

I have  thread over here:   www.ar15.com/forums/topic.html?b=3&f=118&t=273935

Any help from you guys would be appreciated here is a pic of my lower
http://www.themaier.com/lower.jpg

According to the above info my upper should not have a bayo lug?
My upper has the marking of C  H

Based on that one close up pic looks to be a SPII upper on a 6601 lower.

Ekie,

The second pic that "dpmmn" posted looks identical to the rollmarks on my 6601. Also, additional info is on the way to you .



                                                                                                                                  HTH
                                                                                                                                   CI