PM9 chronograph results

[TriggerMan]

Thanks Jim.
I've seen this recommendation to replace the recoil assembly @ 1500 rds. I understand the wisdom of following the manufacturer's recommendation for your carry weapon. I'm sure I'll do the same. My CM9 is nowhere close to that point yet, although at a couple of hundred rounds every week-end...it won't be long..!!
On that topic though...I'm glad you mentioned it. I'm curious to know what functional manifestations might occur at that level of use to signal that it's time to swap.
Is the 1500 rd. swap universally observed, or has someone run their's well over 1500 and can share their experience..??

One can imagine any number of "issues" which might arise from continuing to fire SD rounds with a recoil assembly that has "aged"(weakened..?) from use. Of course, simple failure to function might be an immediately observable signal that one has pushed the envelope a bit too far. A more insidious issue might be that continuing to fire hot SD rounds with a weakened recoil system could begin to allow FRAME DAMAGE.
Anyone...????

Would watching for changes in how far and what direction your shell casings eject be another easy way to time the replacement of the spring assembly?

[jocko]

forgot that, absolutey, especialy if u can remember how it was when new springs were in the gun..

[JimC]

FYI, just because I chose to chronograph the +P+ ammo thru MY PM9 doesn't mean that:

1. I shoot a lot of it thru my PM9.
2. I'm saying it is 100% OK to shoot it thru your PM9.
3. I'm saying it's any better than a good +P round or even a good standard pressure loading.

I shot it to have the data for my use if needed in the future.

As was already pointed out, the 127 gr. +P+ didn't show all that much improvement over the 124 gr. +P Gold Dot for the short barrel pistols.

[jocko]

I nderstand ur point and it looks like from some of ur chrono work that the +P + round is highly over rated to entice the buyer to pay alittle more for what is actually no gain.

without a chrono to do what u did we have no way of knowing what the hell is going on.. nice job by the way.

[OldLincoln]

Jocko, I read that in an early introductory article in a magazine that was on-line. I'll try to find it as I know it was a rabbit trail off a Kahr search.

[OldLincoln]

Okay, I re-ran the trails and found my statement in the Interview of Moon by Massad:.

I was wrong in my assumption that non-gun reasons led Kahr to drop the +P+ okay. See the bold below.

---------------------
Ayoob: You built your first 9mm, the K9, to take 9mm +P and +P+ ammo, and one complaint was that the springs were strong enough to make the gun's slide hard to draw back. Tell us where you went with that.
Moon: The recoil springs in the first K9s were 24 pounds. Based on the feed-back from customers who experienced difficulty in manipulation of the slide, we changed the recoil spring to the current design of 18 to 20 pounds. At this time we only offer one strength of recoil spring in the Kahr K9 models - 18 to 20 pounds.
Ayoob: Did this impact the company's policy of warranting the guns to handle +P and +P+ 9mm, and full power of .40 S&W?
Moon: According to our instruction manual we recommend only high-quality factory ammunition of the proper caliber. The Kahr 9mm can handle +P loads and in the Kahr .40 S&W we recommend regular pressure, high-quality factory ammunition.

[mightymouse]

Is the short barrel GD more than just low flash fast burning powder? Its not about improved velocity.
What about the bullet design that's supposed to expand at lower velocities from a short barrel?

Personally I'm not as worried about using any of the top grade SD ammo in a 3" barrel in 9mm or .40 as they were designed for shorter barrel than the .45, ... big hole regardless, but not as its intended from 5"
I'm sticking to 124 +p SBGD until another better magic bullet comes out.

[MO_Soldier]

Keep in mind, +P+ means more PRESSURE, not more VELOCITY. The 2 don't always equate, as these test results prove!

[jimsea]

....and not that it matters, all things being equal and given identical ammunition, the CM9 barrel has a higher velocity than the PM barrel.

[MO_Soldier]

....and not that it matters, all things being equal and given identical ammunition, the CM9 barrel has a higher velocity than the PM barrel.

What's your source?

[jimsea]

What's your source?

there's a velocity test comparison floating around here somewhere. one of the veterans probably has it handy. sorry, but it would take me forever to find it again.

........the long and the short of it is that the special rifling in the PM matched grade barrel creates more friction with the projectile than the standard rifling in the CM barrel. while the round may be slower out of the PM barrel, the projectile is spinning faster and is technically more stable/accurate.

[MO_Soldier]

there's a velocity test comparison floating around here somewhere. one of the veterans probably has it handy. sorry, but it would take me forever to find it again.

........the long and the short of it is that the special rifling in the PM matched grade barrel creates more friction with the projectile than the standard rifling in the CM barrel. while the round may be slower out of the PM barrel, the projectile is spinning faster and is technically more stable/accurate.

Very well. I like to know the sources of things before acting on them, especially when the life of myself or my family is on the line.
I just uncovered some new information leaning towards 124gr +P rounds in 9mm as being the best 9mm rounds besides +P+, but I don't endorse those anyway because of a lack of standardization/regulation.

I want some Federal Tactical LE HST 124gr +P's now!

[OldLincoln]

Right on, MO! You can find it at Kyles.

[JimC]

....and not that it matters, all things being equal and given identical ammunition, the CM9 barrel has a higher velocity than the PM barrel.

And you base this statement on...?

Traditionally, the conventional rifled barrels produce less velocity than polygonal barrels.

I have found this to be true using a G17 w/the standard barrel and then firing the same ammunition in the same G17 but with a Bar-Sto barrel with conventional rifling.

HK has always made the claim that their polygonal barrels in the USP line produce higher velocities that conventional barrels.

I guess the only way that we will know for sure is for one of us to buy a CM9 barrel and do some chrono testing with the PM9 with CM9 barrel installed. Let's see...$140.80 for a CM9 barrel for testing?????

I don't think so.

[JimC]

This discussion reminds me of the old days, late '70's into the mid '80's, when many of us in LE were carrying the S&W "J" frame 5 shot revolvers off-duty and all the new hyper velocity .38 Spl. ammo was hitting the market.

The one round that everyone wanted was the US Secret Service 110 gr. +P+ load that they had made specifically for them by Win. and later Fed. as I recall. That stuff was hot in those little 1 7/8" "J" frame barrels and they were like flame throwers!!!

S&W came out with a don't use notice for these little guns and this hot ammo. I recall being at S&W for an LE Armorers course for their revolvers back in '85 (yea, I had to dig out the cert. for the date) and the instructors told us that the steady use of this +P+ ammo would stretch the frames on these little guns and render them useless due to misfires because the firing pin could no longer reach the primer sufficiently.

And outside locked in my vehicle was my 2" M36 loaded with that exact US SS 110 gr. load!

Ok I know, I digress here but this came to mind with all of this talk about +P+ ammo.

BTW, the one load that was popular at the time in those little guns was the Rem. 125 gr. JHP load. I don't know if it's even made any longer.