MickB

First check that the mag springs are not in backwards. Also what is your double feed? One empty and one live round or two live rounds? mag blocks are extremely sensitive to position in the magwell for feed reliability. Mick

ASC mags is a clue. ASC is the old C-Products. OEM for Colt is Metalform. For a brief period Colt tried using C-Products/ASC but quickly went back to Metalform for reliability reasons. As Tim also mentioned the other FTF issues in the Colt system is the feed cone of the barrel entering the chamber. Barrels with insufficient angle or sharp edges will cause the incoming round to hang up on the way into the chamber or even worse, drive the projectile into the case. Not all PCC barrels, bolts, and lowers are created equal as people are finding out. Mick

Colt pattern lowers have always had the feed ramp in place due to the feed angle of the magazine used. This style lower has been around since the very beginning. Glock pattern lowers came way later. The feed angle of glock pattern lowers is also different to that of Colt pattern. Since you now have a Colt pattern lower I would suggest you stick to Metalform manufacture mags like those from Brownells or PSA. The mag in your picture looks like an ASC or C-Products mag (orange follower) which are not the most reliable. Mick

Early QC10 glock lowers used to come with a feed ramp. One thing to remember is that QC10 were the original developer of the glock mag pattern AR9 lower receiver (QC10 used to be the company known as DDLES before they were taken over and renamed QC10). The point is that they have been doing the glock pattern lower longer than anyone else. QC10 eliminated the feed ramp in their glock lower for the simple reason that as the cartridge is stripped from the mag, the nose of the round actually enters the chamber while the rear of the cartridge is still held by the magazine feed lips, meaning that in the QC10 glock lower the feed ramp was not needed. Try it with a dummy round and you'll see. Mag well placement in the lower is the key. I cannot comment on other brands of glock pattern lowers but my bet is that those that are having issues with feeding are experiencing "bullet jump" where the round has left contact with the mag feed lips before the round has entered the chamber or the angle of the magazine is such that the round takes a slight nose dive during feeding, which is what a feed ramp would help to cure. Mick

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5.5oz is Colt 9mm SMG spec and the latest versions come with a spacer at the rear of the buffer spring. However, the gun will shoot flatter if you go with a heavier buffer. The VLTOR A5H4 is 6.8oz and the correct length inside a carbine buffer tube to eliminate the need for spacers or a stack of quarters. Testing side by side with the factory Colt buffer system and the VLTOR A5H4 cuts dot bounce roughly in half. Combining the A5H4 buffer with a Tubb .308 flat wire spring gives even less muzzle rise.... Mick

I have one of the first run of the 8.5" barrels. I am loading to 1.15" OAL using Precision Delta 124gr FMJ and have never had an issue. Are you using hollow points by chance? Had a buddy that loaded to same OAL as his FMJ loads and he was getting his rounds hit the rifling in his JP PCC barrel.

Ballistic Advantage or Faxon. I have a Ballistic Advantage 8.5" that I run with 1.15" OAL loads... Mick

Sorry folks. The only Lantac 9mm brake that I was aware of was the one with 1/2x36" thread pattern, which is the US standard for 9mm rifle/subgun barrels. Maybe SIG will change the thread pattern like CZ is doing on their PCC? Mick

Fortis also makes a 9mm muzzle brake in both 1/2x28" and 1/2x36" thread patterns... JP also makes a brake in 1/2x36" thread pattern I have no idea how well they work Mick

Does that Lantac do anything to minimize muzzle rise vs the bird cage? Mick

Either the hole for the buffer retaining pin is out of spec or the JP bolt is too short. If a different bolt pushed the buffer back far enough, then the culprit is the JP bolt... Mick

Not normal. Are you using the factory Colt (metalform) mags? Do you have the same problem when you download to 30rds? Do you have the same problem with the upper removed? Mick

I run a Ballistic Advantage barrel and it has no issues with my 132 PF pistol loads with OAL of 1.15" using 124gr FMJ Precision Delta bullets. Mick

Before you do anything, check your ejector. With the upper off, insert a loaded mag. Are the rounds hitting the ejector (wiggle it around and see if contact with the rounds can be made)? If so, you need to replace or modify the ejector. An ejector issue could explain why the gun works from an open bolt (mag forces the ejector to an out of the way position) and not on a closed bolt. Mick

So, in the case of a carbine gas system, if the aim is to reduce pressure at the bolt, would not a bleed off gas block like the Superlative Arms or the bleed off adjustable bolt carrier like those from 2A or Bootleg be a better mouse trap? Mick

PRO. Bigger tube and is cheaper and comes with a mount... Mick

Mick

Fiocchi also makes them. There were a few of them at SMM3G on the prize tables... Mick

I have the VLTOR A5H4 as well as the enidine hydraulic buffer with Colt spacer. Testing side by side the VLTOR system gives 90 percent of the effect of the hydraulic unit at one third the price. Mick

Factory 9mm Colts come with a spacer. Another alternative is to use the VLTOR A5H4 buffer in a standard carbine buffer tube. It is perfect for length and is heavier than the Colt 9mm smg buffer. Mick

This can also happen if you happen to accidentally reload .380 cases or 9X18. Ask me how I know... Mick

+1 on what Kurt said on clarity. I compared a Swarovski at 6X versus a Mk4 Leupold at 9x and the Swarovski was far superior despite the lower magnification, and that is not to say the Leupold was bad glass... Mick

You will not save much weight using the Colt half circle carrier. They are barely lighter than the standard carrier. There are 2 kinds of half circle Colt carrier. Half circle with non-shrouded firing pin (SP1 type) Half circle with M16 shrouded firing pin (this is the so called Law Enforcement semi auto carrier that came in ban era LEO guns) - I run one of these in my Limited guns. Mick

Not so long ago titanium and then aluminium AR bolt carriers were all the rage. What's the verdict on long term longevity of these materials in bolt carrier applications? How are they holding up? Mick