M&P9 147gr bullets keyholing

[MrPCHead]

Hi folks

I've been scouring the forums here for the last week and while I've found some similar information I haven't seen precisely my situation so here goes...

I've been shooting an M&P9 (4.25" barrel) in Production for the last year. Before getting this gun I had been loading Montana Gold 124gr JHP bullets with 4.1gr of Titegroup and CCI Small Pistol Primers. (OAL = 1.14"). These rounds worked well when I tried them in the M&P so I kept at it. I've not had any complaints after 6-7k rounds and I've had a lot of fun at matches. This summer I decided to revisit the 147gr bullet approach. I bought a case of MG 147 CMJ bullets and set out to find a workable load. I started at 3.3gr of TG, which never made MinorPF (avg 840fps over numerous tests). Of concern to me was that my rounds were keyholing at least 50% of the time. I moved up to 3.5gr of TG and was then able to consistently make right at 850fps but still keyholing quite often. Finally I tried 3.6gr (max load for this bullet) and still could not get rid of the keyholing. I tried various OAL (1.10-1.15) and various heavy/light crimps but nomatter what I did I am getting 30-50% keyholing.

At this point I began to wonder about the twist rate (1 in 18.75") in this shorter barrel. Just for fun I tried some WWB 147JHP rounds and guess what? Keyholing at least 25% of the time! Switching back to 115gr WWB and my previous 124gr handloads = no keyholing at all and good groups. It is worth mentioning that the barrel appears to have clean, sharp lands, a good crown and throat.

As a final data point, I decided to try out my carry pistol (Ruger SR9c)with its 3.5" barrel and guess what? No keyholing with either of the heavy bullets! As it turns out the Ruger has a 1 in 10" twist rate. Hmm.

I called S&W today and they said that 6k rounds was a lot of wear on the gun and that could be the cause of the problem. Seriously? 6k rounds??? They also said that they would be happy to check out the barrel if I would ship it to them. I said I was in the middle of the shooting season and that isn't feasible. The rep said "shoot your matches then send it in". I asked if there were any known problems with this gun and the heavy bullets but he said he could provide no further information about any known issues. Odd that they would take that tack.

Later today I called KKM and asked them what they thought. I spoke with Luke who said he didn't think the twist rate was really the issue but that the "cut rifling" may have been the root cause. He also mentioned that MG bullets were notorious for their thin jacketing and consequent problems. Hmm.

So here I sit with about 2600 of these bullets that I can't shoot. Is it an exclusive problem for the 4.25" barrel? Is 6k rounds too much to ask of a barrel? Would a Storm Lake/KKM/??? barrel solve the problem?

What say you great sages? ;-)

-William

Upper Valley Practical Shooters

Green Mountain Practical Shooters

[98006]

I would suggest you try a different powder. I had keyholing with solo 1k and 147 gr lead. switched just the powder to wst and it all went away.

[MrPCHead]

I would suggest you try a different powder. I had keyholing with solo 1k and 147 gr lead. switched just the powder to wst and it all went away.

Interesting idea. Solo 1000 is certainly a very hot powder compared to WST, but not much different than TG. I would be very keen to know what chrono results you were getting with both. Were you using the same gun as me? What was your specific load data for both?

Thanks!

[8ring]

It could be the slow rate of twist in your barrel, slightly undersized bullets, or both. The Glock 17 and CZ 75 series have rates of twist around 1 : 9.75" and both shoot 147gr bullets quite well.

Chris

[98006]

I would suggest you try a different powder. I had keyholing with solo 1k and 147 gr lead. switched just the powder to wst and it all went away.

Interesting idea. Solo 1000 is certainly a very hot powder compared to WST, but not much different than TG. I would be very keen to know what chrono results you were getting with both. Were you using the same gun as me? What was your specific load data for both?

Thanks!

i am using the same gun as you, a 4.25 MP9. Mine has way more rd through mine though. When I first loaded 147gr I got solo info off the net. the suggested loads all would keyhole. like you i check all the stuff like crimp and stuff.

I'm loading 3.8-4.1 wst at 1.15 with a lead 147gr. I get 900-960 with this load. extremely accurate in my gun. I started at 3.6, but it was too close to the 125pf.

[sdm74]

I have the 5" and I had the occasional tumbler. Since I dropped to 1.10 with 3.5 TG I haven't seen any. Im just over 6k rounds through it. Do you see any strange cuts inside barrel? I remember a post where the guy had some kind of strange cuts inside barrel and it was from poor QC on s&w

[MrPCHead]

i am using the same gun as you, a 4.25 MP9. Mine has way more rd through mine though. When I first loaded 147gr I got solo info off the net. the suggested loads all would keyhole. like you i check all the stuff like crimp and stuff.

I'm loading 3.8-4.1 wst at 1.15 with a lead 147gr. I get 900-960 with this load. extremely accurate in my gun. I started at 3.6, but it was too close to the 125pf.

I'm curious: 3.8-4.1 WST is a pretty broad range. Can you narrow it down? Surely you don't let the charge vary that much, do you?

[MrPCHead]

I have the 5" and I had the occasional tumbler. Since I dropped to 1.10 with 3.5 TG I haven't seen any. Im just over 6k rounds through it. Do you see any strange cuts inside barrel? I remember a post where the guy had some kind of strange cuts inside barrel and it was from poor QC on s&w

Bore, crown and throat all look great.

[Jay870]

I have read various opinions that the M&P 9MM twist is borderline adequate for 147's. A friends Pro keyholed 147's badly until he discovered he was loading too long. After shortening his OAL the gun still would not group 147's well and he ended up going to a Storm Lake barrel. My 9L's OEM barrel shot 147's fine, though I had to load them relatively short.

You mentioned that you've tried a range of OAL's... do you know at what OAL the MG 147 engages the rifling?

[98006]

i am using the same gun as you, a 4.25 MP9. Mine has way more rd through mine though. When I first loaded 147gr I got solo info off the net. the suggested loads all would keyhole. like you i check all the stuff like crimp and stuff.

I'm loading 3.8-4.1 wst at 1.15 with a lead 147gr. I get 900-960 with this load. extremely accurate in my gun. I started at 3.6, but it was too close to the 125pf.

I'm curious: 3.8-4.1 WST is a pretty broad range. Can you narrow it down? Surely you don't let the charge vary that much, do you?

3.8 got me about 900 and 4.1 gets about 950.

[MrPCHead]

I have read various opinions that the M&P 9MM twist is borderline adequate for 147's. A friends Pro keyholed 147's badly until he discovered he was loading too long. After shortening his OAL the gun still would not group 147's well and he ended up going to a Storm Lake barrel. My 9L's OEM barrel shot 147's fine, though I had to load them relatively short.

You mentioned that you've tried a range of OAL's... do you know at what OAL the MG 147 engages the rifling?

Forgot to reply on this one yesterday: Not sure when the rifling would get engaged but it does not at anything up to 1.15, which is the longest I tried. Again, I tried down to 1.10 with no change in the results at all.

FYI, last night I loaded up about 120 rounds with the bullet in question, 3.8gr of WST, CCI SPP, OAL: 1.11 and will hit the range later today. I am not too hopeful but we shall see.

[joedodge]

In all 3 of my m&p i have 2 4 inch and on pro and in my xd tactical im loading 147 gr precision bullets moly coated lead at 1.1 oal with 2.5 grs of solo 1000 and have had n issues what so ever it could be your crimp os a little tight. Oh i make 130 pf with 3.5 also you could drop the charge a little and try that.

[MrPCHead]

In all 3 of my m&p i have 2 4 inch and on pro and in my xd tactical im loading 147 gr precision bullets moly coated lead at 1.1 oal with 2.5 grs of solo 1000 and have had n issues what so ever it could be your crimp os a little tight. Oh i make 130 pf with 3.5 also you could drop the charge a little and try that.

Thanks. You are using different bullets and different powder so I'm not sure your results are relevant to my predicament. I will say that I have tried slightly different crimps (never too tight) with no difference in outcome. As for the powder load, I started light (3.3gr TG) and those were the worst of all. As the charge increased the keyholing got better, but never less than 30% of rounds fired.

The Elephant in the room seems to be the fact that S&W uses this 1 in 18.75" twist rate when Sig, Glock, Ruger, CZ and many others all use 1 in 10". I'm not a gunsmith, mechanical engineer and certainly no physicist but it sure seems to me that the higher twist rate is going to stabilize these heavy bullets more effectively than the slow rate used in my gun.

[sdm74]

The Elephant in the room seems to be the fact that S&W uses this 1 in 18.75" twist rate when Sig, Glock, Ruger, CZ and many others all use 1 in 10". I'm not a gunsmith, mechanical engineer and certainly no physicist but it sure seems to me that the higher twist rate is going to stabilize these heavy bullets more effectively than the slow rate used in my gun.

Yes..but if that was the case no one would be using the kkm barrel which has a 1 in 20" twist

[98006]

I have read various opinions that the M&P 9MM twist is borderline adequate for 147's. A friends Pro keyholed 147's badly until he discovered he was loading too long. After shortening his OAL the gun still would not group 147's well and he ended up going to a Storm Lake barrel. My 9L's OEM barrel shot 147's fine, though I had to load them relatively short.

You mentioned that you've tried a range of OAL's... do you know at what OAL the MG 147 engages the rifling?

Forgot to reply on this one yesterday: Not sure when the rifling would get engaged but it does not at anything up to 1.15, which is the longest I tried. Again, I tried down to 1.10 with no change in the results at all.

FYI, last night I loaded up about 120 rounds with the bullet in question, 3.8gr of WST, CCI SPP, OAL: 1.11 and will hit the range later today. I am not too hopeful but we shall see.

Let us know how it goes. WST is my favorite powder. I use it in 9/40/45

[MrPCHead]

The Elephant in the room seems to be the fact that S&W uses this 1 in 18.75" twist rate when Sig, Glock, Ruger, CZ and many others all use 1 in 10". I'm not a gunsmith, mechanical engineer and certainly no physicist but it sure seems to me that the higher twist rate is going to stabilize these heavy bullets more effectively than the slow rate used in my gun.

Yes..but if that was the case no one would be using the kkm barrel which has a 1 in 20" twist

There is of course more to the story than just the twist rate. According to Luke at KKM the reason they can use the slower twist rate, which he said is around 1 in 18" by the way, is due to 1) button rifling and 2) shallow grooves. Apparently these two factors allow greater contact with the bullet during its travel down the barrel and therefore more rotational forces are imparted. I may very well try a KKM barrel if my tests with the WST today fail to yield better results.

[Bob DuBois]

Check taper crimp, keyholing, tumbling is usually a sign of to much crimp.

Measure the case where the bullet is seated, set crimp .002 under that measurement. The round I just checked measured .378, set crimp at .376, no tighter.

If it still tumbles back off the crimp die just a little more.

Load the rounds as long, I try for 1.140. You may be able to go a little longer just check the first ten in a magazine.

Think you have a loading issue not a barrel issue.

[sdm74]

The Elephant in the room seems to be the fact that S&W uses this 1 in 18.75" twist rate when Sig, Glock, Ruger, CZ and many others all use 1 in 10". I'm not a gunsmith, mechanical engineer and certainly no physicist but it sure seems to me that the higher twist rate is going to stabilize these heavy bullets more effectively than the slow rate used in my gun.

Yes..but if that was the case no one would be using the kkm barrel which has a 1 in 20" twist

There is of course more to the story than just the twist rate. According to Luke at KKM the reason they can use the slower twist rate, which he said is around 1 in 18" by the way, is due to 1) button rifling and 2) shallow grooves. Apparently these two factors allow greater contact with the bullet during its travel down the barrel and therefore more rotational forces are imparted. I may very well try a KKM barrel if my tests with the WST today fail to yield better results.

That's weird on SSS site they have it listed at 1 in 20"

Edited June 22, 2011 by sdm74

[MrPCHead]

Check taper crimp, keyholing, tumbling is usually a sign of to much crimp.

Measure the case where the bullet is seated, set crimp .002 under that measurement. The round I just checked measured .378, set crimp at .376, no tighter.

If it still tumbles back off the crimp die just a little more.

Load the rounds as long, I try for 1.140. You may be able to go a little longer just check the first ten in a magazine.

Think you have a loading issue not a barrel issue.

I didn't go into specifics of the crimp in the original post but I have in fact tried everything you've mentioned. Long, medium or short OAL, heavy/medium/light crimp in every possible combination, none of that made any difference in the keyholing with this gun. More powder/velocity made it a little better. As mentioned, this happened with factory 147gr WWB rounds also.

Then, with a different, 1 in 10" barreled pistol I shot all the exact same rounds with no keyholing. I even went back and forth to confirm what I was seeing. This was over the course of a week with daily trips to the range with multiple iterations of the load and permutations, all carefully labeled.

[Bob DuBois]

How do 115gn bullets fly in your gun?

[MrPCHead]

How do 115gn bullets fly in your gun?

See my original post. The short answer: perfectly. Same with 124gr MG JHPs, which I've been shooting without issue for over a year.

UPDATE: just came home from the range. The WST experiment has yielded odd results. The very first mag (10 rounds) had about 80% keyholing. The next 100 rounds were quite good with only the occasional signs of yaw on the target strikes and then only at the 15 yd distance (the 10 yd target showed perfect hits). Not really sure what to make of that other than perhaps the hot barrel was working better. I had some of the Titegroup versions and they keyholed at both distances over 50% of the time, just like previous tests. Just for fun I shot a mag of the WST rounds though my Ruger SR9c and they showed perfect stability at both distances.

So at this point I think I will load up 1k of the WST version and just run with that for a few weeks. I am seriously contemplating the KKM barrel since they are willing to guarantee its functionality with these rounds.

Stay tuned...

[MrPCHead]

Oops! double post.

Edited June 22, 2011 by MrPCHead

[wanderer]

if your only running them at 850fps, as in your 1st post they are too slow, crank those puppies up to 920-930fps and see if that helps.

[98006]

How do 115gn bullets fly in your gun?

See my original post. The short answer: perfectly. Same with 124gr MG JHPs, which I've been shooting without issue for over a year.

UPDATE: just came home from the range. The WST experiment has yielded odd results. The very first mag (10 rounds) had about 80% keyholing. The next 100 rounds were quite good with only the occasional signs of yaw on the target strikes and then only at the 15 yd distance (the 10 yd target showed perfect hits). Not really sure what to make of that other than perhaps the hot barrel was working better. I had some of the Titegroup versions and they keyholed at both distances over 50% of the time, just like previous tests. Just for fun I shot a mag of the WST rounds though my Ruger SR9c and they showed perfect stability at both distances.

So at this point I think I will load up 1k of the WST version and just run with that for a few weeks. I am seriously contemplating the KKM barrel since they are willing to guarantee its functionality with these rounds.

Stay tuned...

you going too slow. bump it up to 4.1

[MrPCHead]

How do 115gn bullets fly in your gun?

See my original post. The short answer: perfectly. Same with 124gr MG JHPs, which I've been shooting without issue for over a year.

UPDATE: just came home from the range. The WST experiment has yielded odd results. The very first mag (10 rounds) had about 80% keyholing. The next 100 rounds were quite good with only the occasional signs of yaw on the target strikes and then only at the 15 yd distance (the 10 yd target showed perfect hits). Not really sure what to make of that other than perhaps the hot barrel was working better. I had some of the Titegroup versions and they keyholed at both distances over 50% of the time, just like previous tests. Just for fun I shot a mag of the WST rounds though my Ruger SR9c and they showed perfect stability at both distances.

So at this point I think I will load up 1k of the WST version and just run with that for a few weeks. I am seriously contemplating the KKM barrel since they are willing to guarantee its functionality with these rounds.

Stay tuned...

you going too slow. bump it up to 4.1

First, to answer Wanderer: The 850fps was with 3.5gr of TG. I never bothered chrono'ing the 3.6 due to the poor stability. I suspect the latter easily made MinorPF. Now, this brings up an interesting point: those rounds using 3.6gr of TG showed signs of over pressure, i.e., the primers showed a considerable raised bulge in the teardrop shape of the breach face opening. No real problem but clearly this is a max load for a reason. Yesterday's rounds with 3.8gr of WST showed very little of this so I suspect I could in fact bump the powder up to 4.0 or even 4.1gr as 98006 is doing. But...at that load I really question whether this is an improvement over my Production load of the past year (MG JHP 124gr, TG 4.1gr, CCI SPP, OAL: 1.11).

My entire reason for moving to the 147gr bullet was to reduce felt recoil so as to make my splits faster. I was consistently at 128pf year-round with the 124gr load but now I'm headed for 140pf, just to get a stable bullet in flight. Is this progress???

*sigh* I guess I will load up some 4.0 and 4.1gr rounds right now and...head to my second job this afternoon: the range. ;-)