Good test report tktm.
I would say it is highly likely that IN YOUR P7 this round is in fact causing "overfunction" due to excessive slide velocity. Some of the key indicators are:
1. The FTFeed stoppages happen on the last round and are "nosed up" above the chamber opening and;
2. The round has a high projectile weight and descent chamber pressure and;
3. The stoppages were reduced with new Wolff springs and;
4. The slide failed to lock open on the empty mag (the slide hits the frame so hard the mag follower is knocked down by that impact and cannot engage the slide stop. This same impact knocks the last round forward out of position in the mag and when the slide comes back forward also too fast it strikes the out of position round which then "jumps" out from under the feed lips versus vs being fed under control out of the mag as intended - CLASSIC nosing up caused by overfunction).
The recoil impulse of a round is determined by the internal pressure, propellant used and bullet weight along with other factors. It need not be a 147 grain projo in the round to do this and bullet weight alone is not the only deciding factor.
The other side of the coin is the P7 and its condition. Remember HK addressed this issue by lengthening the length of the feel lips on M8 mags to be longer like those on the M13 and created a field gage to measure piston wear. Your M8 may have a combination of both plus the weaker older mag springs and this particular ammo put it outside the reliable operational limit that all firearms have. Remember that the P7 was designed for 124 grain NATO spec ammo. They do not recommend ammo under 100 grains or the 147 grain stuff even though it will work in some P7's.
Obviously I would not recommend that particular 127 grain +P+ round in YOUR P7.
I carry and shoot a Rem 124 grain +P+ round that in my P7M8's runs well and shoots accurately. However all my mags are the longer feed lip style (IH dated - 1987 - or later), have fresh factory mag springs every 5th year, are downloaded by one for storage and I check my pistons yearly. Each gun is different which is why I usually tell folks find a defense round that shoots 100 out of 100 rounds without issue in your particular pistol and stick with it.
G3Kurz
I would say it is highly likely that IN YOUR P7 this round is in fact causing "overfunction" due to excessive slide velocity. Some of the key indicators are:
1. The FTFeed stoppages happen on the last round and are "nosed up" above the chamber opening and;
2. The round has a high projectile weight and descent chamber pressure and;
3. The stoppages were reduced with new Wolff springs and;
4. The slide failed to lock open on the empty mag (the slide hits the frame so hard the mag follower is knocked down by that impact and cannot engage the slide stop. This same impact knocks the last round forward out of position in the mag and when the slide comes back forward also too fast it strikes the out of position round which then "jumps" out from under the feed lips versus vs being fed under control out of the mag as intended - CLASSIC nosing up caused by overfunction).
The recoil impulse of a round is determined by the internal pressure, propellant used and bullet weight along with other factors. It need not be a 147 grain projo in the round to do this and bullet weight alone is not the only deciding factor.
The other side of the coin is the P7 and its condition. Remember HK addressed this issue by lengthening the length of the feel lips on M8 mags to be longer like those on the M13 and created a field gage to measure piston wear. Your M8 may have a combination of both plus the weaker older mag springs and this particular ammo put it outside the reliable operational limit that all firearms have. Remember that the P7 was designed for 124 grain NATO spec ammo. They do not recommend ammo under 100 grains or the 147 grain stuff even though it will work in some P7's.
Obviously I would not recommend that particular 127 grain +P+ round in YOUR P7.
I carry and shoot a Rem 124 grain +P+ round that in my P7M8's runs well and shoots accurately. However all my mags are the longer feed lip style (IH dated - 1987 - or later), have fresh factory mag springs every 5th year, are downloaded by one for storage and I check my pistons yearly. Each gun is different which is why I usually tell folks find a defense round that shoots 100 out of 100 rounds without issue in your particular pistol and stick with it.
G3Kurz
