Bolt Carrier exhaust vent size variations

[tom12.7]

Just to expand a bit about the cam path altering touched on earlier.
What happens if the pre travel in the cam event is reduced via BCG modifications, leaving the other items the same as TDP? With all safety concerns dealt with, obviously.
How does this alter the operation of the system as a whole work when concerning the 3 examples of 20" rifle gas, 14.5" carbine gas, and 10.5" carbine gas?
I won't write too much, as I tend to lose posts here.
If done incrementally some trends seem to show.
The 20" does require more gas to operate compared to a std TDP BCG.
The 14.5" requires more, while the 10.5" requires more than the 14.5".
Brass stretch and visible extractor pull marks become much more obvious as the pre travel shortens.
The same can be shown with both rifle and carbine actions for the listed barrel lengths.
So, what to make of all of this about the cam path?
Is it ideal in the TDP? No.
Can options be made to change some of the issues? More than likely so.
So, from here, what can be done to look into the options we have available, like the LMT Enhanced Carrier and others?

[BufordTJustice]

I would personally prefer if BCM didn't use CMT cam pins though. The CMT cam pins tend to wear uppers more and break more often in the firing pin hole area than others. Just a visual check shows that they relieve the firing pin hole coarsely and they have sharper edges at the top of the pin. Some complain about how LMT cam pins wear a groove, but they don't wear other components like the CMT have. I have swapped out CMT cam pins out of many "premium" builds and throw in a few LMT pins for many, including Noveske.

I've been using LMT cam pins until i switched to NiB cam pins. Those don't wear either the upper or the bolt as much. But, now, I'm using the V7 cam pin and I don't think I'll be using anything else from here on out.

[E-man930]

Not to sidebar this awesome thread but H&K cam pins... You won't go back.

[JoshNC]

Not to sidebar this awesome thread but H&K cam pins... You won't go back.

Where did you find these?

[BufordTJustice]

Not to sidebar this awesome thread but H&K cam pins... You won't go back.

Pix please.

[sinlessorrow]

Pix please.

From all looks it is just a basic cam pin that costs $20.

[tom12.7]

It could be great, it could be mediocre, I don't know? I don't doubt HK's quality standards, but the top of the pin seems to lack a more rounded radius on the corners than what I prefer, but it's just a picture and not in my hands.

[HKGuns]

No gas ports, obviously, but a nice view of a real HK cam pin.

[BufordTJustice]

No gas ports, obviously, but a nice view of a real HK cam pin.

I'm sure it's of typical HK quality.....but i prefer the rounded corners of the V7.

[sinlessorrow]

Just an update.

According to colt it varies between .110 and .120. The rear carrier/top carrier in this pic has .120" vent ports, and the front carrier/bottom carrier has .110" vent ports.