[tktm]

Finally got a chance to test the newest version of Winchester's 127gr +p+ RA9TA "T-series" in a P7M8. In the latest incarnation of this round, the hollow point is wider and shallower than previous version. Basically I was looking to see if the design changes improved reliability in P7M8's as compared to the older version where I encountered a Failure to Feed Jams approximately every two hundred rounds. see

http://www.hkpro.com/forum/hk-handg...3-have-differing-ammo-reliability-issues.html

I had hoped that the hollow point profile change might reduce the jamming likelihood against the sides of the barrel/chamber.
The test involved 2 different shooters and 2 different P7M8's (each shooter shot both guns).
The "T-series" ammo induced a previously unseen failures in both guns with both shooters.
The issues were as follows.
(1) Failure to feed with breech face crushing the side of the cartridge against the chamber (last round)
(2) Failure to lock back slide

Of the 150 rounds fired, only 1 magazines worth (8 rounds) ran without a stoppage.
In an effort to remedy the issue, the magazine springs were replaced at approximately the 80 round mark with new +10% wolf springs.
It was after the change over to the Wolff mag springs when we finally had a total of 1 magazines without a failure to feed.
The shooting was done over 3 different trips to the range.
Additionally we fired 124gr +p Ranger Q4362 with ZERO malfunctions, and also had ZERO malfunctions with a hot custom loaded 100gr +p+ round (much greater recoil than the other rounds fired).

It is possible that increasing the recoil spring weight might reduce the proclivity of the new 127 grain to fail in the manner we described. However it would seem that the current loading of the RA9TA "T-series" has a sweet spot for failure in P7M8's, hence it is probably best avoided.
We also noted a slight reduction in accuracy and precision in the new T-series as opposed to the original "Black Bullet" SXT loading of the round.

The photos below show the "T-series" fired at a silhouette from a standing position at 25 yards, and the last round FTF jam in the gun after new mag springs had been installed. With the new springs the jam location changed slightly, there was less crushing of the side wall of the cartridge.

 

[TGS]

Good post!

Maybe G3Kurz can comment.....my SWAG is that this is caused by over-function, similar to use 147gr rounds. The 42,000psi chamber pressure with 127gr bullets probably produces significantly more impulse than the 124gr+p, or the 100gr +p+.

IIRC, the P7M8 that jammed on Trooper Gonzalez failed in the same way as your 1st stoppage; this is one reason I'm thinking over-function, since that's what the problem was with the NJSP P7M8's when using 147gr ammo.

Hopefully G3Kurz can chime in.....after all, he was part of/or led the investigation on why Trooper Gonzalez's weapon failed him. He's certainly familiar with P7's and ammo incompatibility.

 

[G3Kurz]

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

 

[tktm]

The older SXT rounds (black) didn't have these kinds of frequent jams (in my pistols), the T-series do.
The new 127's just seem dialed in to fail.
If I had to pick a round most likely to fail in the P7M8 it would be the new T-series 127gr +p+

The 100gr round I'm shooting clocks 1550-1600 fps in our P7M8's; its felt recoil is definitely greater that the 127gr, and that's what makes the situation interesting.

The mags are dated JB and IR. Is there a photo some where that shows the differences in the magazine feed lips post/prior to the change?
The pistons visually look and feel good; but where does one buy the piston field gauge?

Thanks
TKTM

 

[TGS]

The older SXT rounds (black) didn't have these kinds of frequent jams (in my pistols), the T-series do.

I'm confused; as I'm citing below, you stated that you were testing to see if RA9TA is more reliable than the older SXT 127gr +p+. That would make me think that the SXT wasn't reliable in your gun.

Finally got a chance to test the newest version of Winchester's 127gr +p+ RA9TA "T-series" in a P7M8. In the latest incarnation of this round, the hollow point is wider and shallower than previous version. Basically I was looking to see if the design changes improved reliability in P7M8's as compared to the older version where I encountered a Failure to Feed Jams approximately every two hundred rounds.

The 100gr round I'm shooting clocks 1550-1600 fps in our P7M8's; its felt recoil is definitely greater that the 127gr, and that's what makes the situation interesting.

1) Inertia and energy are not the same.

2) Felt recoil is subjective.....for instance, people will judge the severity of recoil based on different traits, such as the snappiness instead of front-sight tracking ability.

 

[tktm]

I'm confused; as I'm citing below, you stated that you were testing to see if RA9TA is more reliable than the older SXT 127gr +p+. That would make me think that the SXT wasn't reliable in your gun..

The Black SXT round was not reliable enough for me; with it I would have a failure to feed around once every two hundred rounds. The crenelated edges of the SXT hollow point would catch in the red circled areas shown in the photo below. With the new T-series version the failure rate jumped to 1 every 8 rounds.

 

[TGS]

Gotcha, thanks for clarifying.

I don't understand why the edges you've circled would cause a problem. The P7 feeds almost directly into the chamber. I would think those areas shouldn't be anywhere near the opening of the JHP....have you cycled it by hand (slowly) to replicate it?

As for the piston gauge, I don't think it's a public market item. I believe only agency armorers were able to obtain them.

Thanks,

TGS

 

[tktm]

Gotcha, thanks for clarifying.

I don't understand why the edges you've circled would cause a problem. The P7 feeds almost directly into the chamber. I would think those areas shouldn't be anywhere near the opening of the JHP....have you cycled it by hand (slowly) to replicate it?

As for the piston gauge, I don't think it's a public market item. I believe only agency armorers were able to obtain them.

Thanks,

TGS

You can see from the dot on the feed ramp where the rounds were feeding; my guess is that the at a certain angle of rotation the tip of the bullet would deflect slightly left or right when it hit the ramp. The high impulse probably did not help matters any. The mouth of the HP would catch right in the sharp edge shown in the red circles. I did not replicate that failure by hand cycling, 1 in 200 is a lot of cycling.

 

[chuck s]

I no longer have a P7PSP but Winchester Ranger-T 147gr (RA9T) functioned reliably and is my 9mm cartridge of choice in both my USP9C and P2000SK as well.

-- Chuck