I have a GS-prefix 6550 rifle and noticed that the bolt has an interesting "Dot Matrix" style of marking. Below is a picture of my bolt so you can see what I am talking about:



Is anyone familiar with this style of bolt marking? I would like to know when it was used and whether or not it is correct for a 1990 production 6550 rifle. This style seems to be different from the earlier SP1 style of Colt marking as well as the current style of the MPC marking.

If anyone furthermore has a GS-prefix 6550 and wouldn't mind posting a picture of their bolt markings, I would greatly appreciate that.

I don't believe that is the correct bolt for the rifle. [and I have a GS prefix 6550]

That's what I was thinking - the rifle is otherwise all correct, but I suspect that the previous owner may have accidentally mixed up the bolt carrier group with another rifle. Would you be able to post a picture of your bolt markings? I would appreciate it.

Let me see what I can do.

OK, pretty faint but it can be seen.

And thanks!!!!, I had these stashed away in the same place, had forgotten all about them along with 2 full carriers with bolts.

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I think those are all Colt bolts but with different markings.

I will say that the GS one, though faint [it's the correct one as the carrier FP is unshrouded, all my others are F/A carriers, IE full shrouded.] does sort of look as it might be dot matrix type MAYBE. It's more yellowish then anything else.

Thank you for getting back to me! Just to be clear here, you are saying that your first picture is the bolt pulled from your GS-prefix rifle whereas the set of three bolts in your second picture come from different rifles?

It really looks like the bolt in your first picture has exactly the same "Dot Matrix" type marking as my bolt does. Perhaps this style of marking is indeed correct for the GS-prefix rifles then.

It does however seem that the middle bolt in your second picture is actually an FN mfg unit as it is stamped MPF.

It should be noted that Colt changed the marking style several times during the 1990's and it could very well be possible that several different types of marking style appeared on bolts found in GS-prefix guns from the factory.

One important thing I have noticed is that the SP1 type rifles all seem to have bolts marked "MPC" with the "M" and "P" joined together into one glyph. Any some point, Colt seems to have changed to marking the bolts "MPC" with all the letters separated. I am trying to figure out exactly how this change occurred as it seems that Colt changed the font a few times as this change occurred.

Yes, first one is the one from my GS prefix rifle.
Other 3 bolts were ''GI surplus'' bolts'' $25 [each] back in the day if you bought multiples. Oh for those days back, most looked as if they were never used and you could pick and choose.

Well let me look at my late SP1...........

You are correct though VERY faint, same type marking on the barrel.

That middle bolt is 100% FN

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