I am looking at putting together a dependable 9MM conversion kit for use in a Colt select fire 5.56MM lower. Are the current production ramped 9MM Colt F/A bolts ramped sufficiently? Or would it be better to send an F/A Colt 9MM bolt off to M60joe/MGP/ADCO to be ramped? Is the CMMG enhanced Mk9 ramped bolt a better option than the Colt bolt? TIA!

Maybe it's just my perception, but nowadays it seems as if all 9 mm AR bolts are ramped with the same or very similar profile.  Also, having the bolt already slotted to accommodate a single feed magazine (e.g., Glock mags) is becoming more and more common.  I'm guessing the extra effort of stocking multiple bolts costs more than a couple extra steps on a milling machine costs.

MHO, YMMV, etc.

That is the problem. As I understand it, different ramped bolts are ramped at different angles and to different depths. M60Joe ramps at 3 degrees, MGP ramps at 5 degrees same as the factory 5.56MM bolt, and the factory Colt ramped F/A bolt appears to be different yet. And the depth (length) of the ramp appears to be different on all of them. Steve at ADCO uses a shorter ramp. If the current factory Colt ramped 9MM F/A bolt is ramped sufficiently for use in a factory Colt M16A2 lower with OEM 5.56MM FCG, that will make the choice easy.

EDIT: This 9MM setup is for the many kids in the family so it will get the hell shot out of it. Choosing the correct ramped 9MM bolt will help the lower receiver wear more normally. Been using KNS pins since they came out so have that covered. Thought about just picking up a military grade 9MM SMG such as a Vector Uzi. But I want the kids to grow up using the AR15/M16/M4 platform for simple target shooting then move on to SD/HD/hunting.

You may be over thinking this with the apparent assumption that there is one true correct. best, optimal ramp angle, length and shape (Who is to say that a linear ramp is optimal?  But I have not heard of any other shape).  All of the ramps eliminate the short, sharp impact the results from an unramped bolt and stretch out the impact energy over a longer time.  As far as I can tell (never having seen any reports to the contrary), all of the ramped bolts provide the same effect with the same effectiveness.

FWIW, the CMMG and Spinta Precision 9 mm bolts that I have appear to have virtually identical ramps.

Best of luck with whatever you decide to pursue.

MHO, YMMV, etc.

Your input is appreciated. Will start off with the current factory Colt ramped F/A 9MM bolt and go from there.

The current OEM ramped Colt 9MM bolt works well with the Hahn bottom loading mag block fed by the very affordable PSA 32rd. mags manufactured by Metalform, same folks that make the pricey OEM Colt 9mm mags. Will start sourcing a MK-9K can.

EDIT: Be sure to use a 9MM buffer spacer or longer-than-standard-carbine dedicated 9MM buffer on any AR15/M16 9MM setup. Without the spacer/9MM length buffer, you are open to several malfunctions.  The 9MM bolt catch can break or worse yet, a spent case can get into the hammer/trigger area rendering the weapon unusable. Colt was advised that such a malfunction took place down in SA. So an aluminum 0.750" 9MM buffer spacer was designed for use in the newer Colt 9MM carbine/SMG to prevent that condition.

I have the m60 joe ramped and a cmmg ramped. The reason i have two is i tried both because the dam thing was just runaway full auto..neither fixed my issue. I removed my geissele SSF trigger and installed a GI m16 FCG and my problem was solved.. i prefered the m60 joe ramp. It just felt smoother and less likely to beat up trigger hammer pins..in the end for me it doesnt really matter since i run Rdias, but if i had a RR if i didnt avoid 9mm completely (because wear and i just dont care for it) i would go with the m60 joe ramp if it functions.

Many people run m60 joesramp with the SSF successfully....just refused to work for me after several range trips so i just wanted it to work.... the SSF is a great trigger

The SSF trigger group is a high quality product. But it would not work in auto with the Ciener .22 conversion kit I have been using for animal control at night over the past couple decades. Other shooters report that their SSF group works fine with a .22 conv. kit. Might be an example of tolerance stacking on the factory Colt 723 lower I use. The SSF worked fine with the 5.56MM uppers. M60 joe puts a much longer ramp on a 9mm bolt. The Colt ramp is noticeably shorter, approx. 1" VS 1.5". If I have any trouble with the current Colt ramped 9mm bolts I have, will send one to m60joe for ramping. But will first verify with m60joe that his ramped bolt will work with standard mil-spec M16 hammer. The OEM Colt ramped 9MM bolt works fine with the standard M16 hammer. Appreciate your input.

Source for Colt ramped 9mm bolt?

They can be found on GunBroker, maybe the ee.

Funny my SSF trigger worked with my CMMG .22 kit which is identical to a ceiner.

There was defiantly some tolorance issue with my 9mm kit that i never resolved, im going to be putting the SSF back in...i always though the SSF could be that good till i used it.. going back to the SSF from what ive been using will be nice.

The aluminum OEM COLT 9MM receiver extension/buffer spacer, p/n SP400211, is now available from Brownells: http://www.avantlink.com/click.php?tt=cl&pw=55963&ctc=j4styv66jo00zk8a00y51&mi=10077&url=http%3A%2F%2Fwww.brownells.com%2Frifle-parts%2Fstock-parts%2Fbutt-plate-parts%2Fbutt-plate-components%2Far6951-spacer-sku160308286-82182-171691.aspx?sku=160-308-286