What's wrong with my load?

[Six]

This morning I went out to test a load based on many posts around this forum, it's the first time I've ever loaded this particular bullet, and first time using N320.

Did I miss something, or screw something completely up?

Details:

• Caliber - 9mm
  
• Bullet - Missouri Bullet 147gr Lead FP
  
• Powder - 3.2gr VihtaVuori N320
  
• Primer - Federal Small Pistol
  
• OAL - 1.142"
  
• Brass - Mixed
  

Here's the result

• Min - 905.1
  
• Max - 962.5
  
• Avg - 934.2
  
• Stdev - 16.37
  

I followed this with some different loads of TiteGroup under a 124gr JHP, and this came out exactly where they were expected to at a 125-135 PF, that made me fairly certain that the chrono hasn't gone nuts. The chrono is a shooting chrony Alpha, set up at 7yards. The screens had blue sky above them, but no direct sunlight.

I have previously loaded some 147gr JHPs over Titegroup, and those were very soft shooting loads. This one obviously had quite a bit more push to it.

My first thought is that I need to move the OAL to the full 1.169", any other suggestions?

Thanks,

Edited October 17, 2010 by Six

[freakshow10mm]

147gr @ your 934fps is 137.3 PF. If you were aiming for 135 PF you're 2PF off your mark.

If you are targeting a softer load, increasing your OAL (all else equal) will reduce your pressure and thus velocity.

Load up 2-3 dummy rounds at the OAL you want, then test them with hand cycling the gun. If they pass, load up some rounds and try them.

When using a new bullet, I always advise to use the longest OAL that will feed 100% in your weapon. Then develop your data from there.

You haven't stated your intended goal with the load in question, I can only assume you want it softer and closer to a 130PF. If that's the case, then increasing your OAL will reduce pressure and will in turn reduce velocity.

[Six]

Yeah, these are supposed to be soft plinking loads and I was aiming for a 125-130 PF. Just enough to meet minor for club matches.

This seemed like a well used and liked load, so I guess I am mostly surprised that a .027 difference would account for that large a velocity difference and wanted to check if anyone had experience with this particular load.

[Sarge]

I'd be willing to bet you won't notice a difference in a 130 vs a 137 pf load. I know you want something light for just club matches but you should consider a few things. 137 pf is a good load. You should shoot what you may want to use in a bigger match someday where there will be a chrono. You never ever want to go for 125 in that regard. Many people target 135 for minor loads.

What gun are you shooting these through. Loading a 147 down to 125 pf might be too light for the gun and lead to cycling issues with a stock set up.

But if none of that matters to you then by all means drop the charge to 3.0 or stretch them out a little as already mentioned.

[Six]

Yeah that's kinda of important, doh. I'm shooting an M&P Pro.

I'm loading up a separate load to use for most matches, those have a PF of about 132 and will be my "standard" load. (124gr MG JHP / 4.0gr TG BTW )

These are just for more affordable shooting, but I'd like to have them meet PF so I have the option of using them in local matches without too much guilt.

So what I'll do is start over at 1.169" (or whatever the gun likes), and then start a bit lower and work my way back up.

[Sarge]

By all means make a sample round like mentioned above. Take the barrel out of your pro and drop check the dummy round. Should kerplop in and fall out with no resistance . If it touches the rifling at all it will give you fits when shooting. 1.169 might be pushing it for an M&P. Not sure of the profile of the missouri but I tried some precision moly 147 FP's in my pro and had to cut all the way back to 1.10 to drop free.

Good luck.

[G-ManBart]

Yeah that's kinda of important, doh. I'm shooting an M&P Pro.

I'm loading up a separate load to use for most matches, those have a PF of about 132 and will be my "standard" load. (124gr MG JHP / 4.0gr TG BTW )

These are just for more affordable shooting, but I'd like to have them meet PF so I have the option of using them in local matches without too much guilt.

So what I'll do is start over at 1.169" (or whatever the gun likes), and then start a bit lower and work my way back up.

132PF is too light to take to a match where they might chrono. Go read the thread about the big name guys going sub-Minor at the US IPSC championship. They were running a load that "normally" runs about 132-133PF in my M&P Pro (one of them was shooting an M&P Pro as well, can't recall the others). If you're not over 135PF, you're taking a big risk of going sub-Minor and not shooting for score. Nobody, nobody, nobody can tell the difference between a 132PF load and a 135PF load. The extreme spread is a bigger gap than that, so it's a totally inconsequential difference. The load I worked up for my Pro is right at 137PF and is so soft that when my wife (she's 5'2", 105lbs) shot it, she said "OMG, this is a wussy gun, anybody could shoot it. If a petite female with tiny hands has no problem with it, nobody should. It's just a matter of setting the load and getting used to the feel...then it won't really matter at all.

For your goal of plinking/fun ammo, don't mess with the OAL if the gun is running properly. Set the OAL based on what fits in the magazines, and what feeds in the gun, then adjust the powder charge to get the velocity you want. I don't know why people always want to mess with OAL to adjust the velocity, but it's absolutely the wrong way to go about it. R,

[freakshow10mm]

Set the OAL based on what fits in the magazines, and what feeds in the gun, then adjust the powder charge to get the velocity you want. I don't know why people always want to mess with OAL to adjust the velocity, but it's absolutely the wrong way to go about it. R,

I agree. Set your OAL first, then work your powder charge to fit.

135 PF is minimum for a cushion and what I load 9mm Minor to perform. Most factory 9mm ammunition is loaded between 135 and 140 PF. 2 PF with a 147gr bullet is a mere 12-14fps. 135 PF 9mm is still very pleasant to shoot.

[Six]

Yep, and in this case it seems my OAL might be too short.

Bart, I was working as a club volunteer at the IPSC match two stages over from the chrono and remember well when word spread of people going sub minor. Definitely don't want that to happen so I want to have a load which gives enough margin to ensure it I won't.

With the TG loads I worked up for 124JHP, 4.0gr gives me a 132PF, 4.1gr gives me 135. They shoot the same, so I'll go with the one with a bit more margin.

Thanks

[Shadowrider]

Yeah, these are supposed to be soft plinking loads and I was aiming for a 125-130 PF. Just enough to meet minor for club matches.

This seemed like a well used and liked load, so I guess I am mostly surprised that a .027 difference would account for that large a velocity difference and wanted to check if anyone had experience with this particular load.

.027" OAL will make a noticeable difference in a small capacity case like 9mm.

[Six]

Followup: Bumping the OAL to 1.169" gave me some more numbers, not too far from the ones I had before, though the load seemed to shoot a bit softer.

Again, this is a Missouri Bullet 147gr LFP shot in a M&P Pro using Vihtavouri N320.

FPS								
Grain	 2.8 	 2.9 	 3.0 	 3.1 	 3.2 	 3.3 	 3.4 	 3.5 	 3.6 
Min	 824.1 	 843.2 	 853.0 	 874.1 	 902.0 	 902.0 	 913.0 	 955.8 	 974.1 
Max	 856.6 	 880.9 	 886.4 	 897.3 	 926.6 	 950.0 	 983.0 	 994.2 	 1,020.0 
Avg	 840.9 	 859.0 	 872.4 	 889.0 	 913.0 	 930.0 	 954.0 	 971.4 	 998.0 
Spread	 32.4 	 37.7 	 33.5 	 22.5 	 24.7 	 47.9 	 70.6 	 38.4 	 46.7 
SD	 13.5 	 14.1 	 12.9 	 10.0 	 7.7 	 16.3 	 24.4 	 11.9 	 15.0 

Power Factor									
Grain	 2.8 	 2.9 	 3.0 	 3.1 	 3.2 	 3.3 	 3.4 	 3.5 	 3.6 
Min	 121.1 	 124.0 	 125.4 	 128.5 	 132.6 	 132.6 	 134.2 	 140.5 	 143.2 
Max	 125.9 	 129.5 	 130.3 	 131.9 	 136.2 	 139.7 	 144.5 	 146.1 	 149.9 
Avg	 123.6 	 126.3 	 128.2 	 130.7 	 134.2 	 136.7 	 140.2 	 142.8 	 146.7 

[8ring]

Six:

Your latest data is consistent with my results. Two ten round strings of 3.1gr N-320 under 147 Bear Creek Moly-Coated bullets in FC cases with Win small pistol primers gave the following results:

Hi 895 893

Lo 866 869

Av. 879.4 878.9

Ex Sp 28.15 23.30

SD 10.81 8.71

PF 129.27 129.19

Weapon is a CZ 85. These were the softest shooting 9mm rounds I've ever used. Too bad lead and moly coated bullets don't agree with my CZ's barrel.

Chris

[G-ManBart]

Followup: Bumping the OAL to 1.169" gave me some more numbers, not too far from the ones I had before, though the load seemed to shoot a bit softer.

Again, this is a Missouri Bullet 147gr LFP shot in a M&P Pro using Vihtavouri N320.

FPS								
Grain	 2.8 	 2.9 	 3.0 	 3.1 	 3.2 	 3.3 	 3.4 	 3.5 	 3.6 
Min	 824.1 	 843.2 	 853.0 	 874.1 	 902.0 	 902.0 	 913.0 	 955.8 	 974.1 
Max	 856.6 	 880.9 	 886.4 	 897.3 	 926.6 	 950.0 	 983.0 	 994.2 	 1,020.0 
Avg	 840.9 	 859.0 	 872.4 	 889.0 	 913.0 	 930.0 	 954.0 	 971.4 	 998.0 
Spread	 32.4 	 37.7 	 33.5 	 22.5 	 24.7 	 47.9 	 70.6 	 38.4 	 46.7 
SD	 13.5 	 14.1 	 12.9 	 10.0 	 7.7 	 16.3 	 24.4 	 11.9 	 15.0 

Power Factor									
Grain	 2.8 	 2.9 	 3.0 	 3.1 	 3.2 	 3.3 	 3.4 	 3.5 	 3.6 
Min	 121.1 	 124.0 	 125.4 	 128.5 	 132.6 	 132.6 	 134.2 	 140.5 	 143.2 
Max	 125.9 	 129.5 	 130.3 	 131.9 	 136.2 	 139.7 	 144.5 	 146.1 	 149.9 
Avg	 123.6 	 126.3 	 128.2 	 130.7 	 134.2 	 136.7 	 140.2 	 142.8 	 146.7 

How many strings of the 3.2gr load did you shoot, and how many rounds in each string? If you didn't do a couple of 20-round strings, the difference between today's results, and the previous post (23fps) is almost insignificant, from a statistics standpoint. Also, the exact same batch of ammo will produce slightly different results on different days (even with relatively similar conditions).

As far as which feels softer...no, you're almost certainly going to feel 20fps difference in average velocity, and comparing what you felt on one day, with what you feel today, absolutely doesn't work. The extreme spread within your string was more than that (24.7) and you probably didn't think "oh, that one felt light, that one felt heavier" etc. Pick a load that gives you the PF you want, load a whole bunch of them, and practice with them. Your body will compensate (sometimes with the help of a few timing drills) and you'll be able to shoot them to the level of your ability. If you get dialed in to one load, and then were to switch to one that's significantly softer, or hotter, you won't shoot them as well until you get used to it (couple hundred rounds or so).

Sort of like what Flex says "pick one and practice". R,

[Six]

Actually, the "felt" softer was more in regards to the higher powder loads which I didn't include in my first post. They had a far more noticeable recoil than the second batch of same powder weight with a longer OAL.

[G-ManBart]

Actually, the "felt" softer was more in regards to the higher powder loads which I didn't include in my first post. They had a far more noticeable recoil than the second batch of same powder weight with a longer OAL.

What was the difference in velocity between the higher PF loads and the second batch with the same weight powder at a longer OAL? If it's not pretty significant, like 50+fps, it's an impression that will vary from day to day. I've proven to people that they couldn't feel that much difference (and more)...just shoot a couple rounds over the chrono and try telling which is which, when you can't see the readout.

So, how many strings and rounds per load did you include when making the chart above? R,

[Duke Nukem]

Let me guess they tumble. Just use WSF or slower powder and you can use all the lead an moly you want.

My Shadow Custom shoots them fine. No leading or tumbling.

Too bad lead and moly coated bullets don't agree with my CZ's barrel.

[Six]

Alright, my impression was that the second batch had a softer recoil, maybe I'm wrong, not important enough of a point for me to go dig up my notes.

I shot 10 rounds each over the chrono, enough to find some ballpark numbers to start working with.