The .2 of a grain difference

[Kiwi cop]

As I posted in an earlier thread, I have been disappointed in my usual 9mm load in my Kimber 1911. This load (5.5 gn of locally repackaged Winchester Action Pistol powder under a 124 gn PRN projectile) is the same as the commercial loading the repackager is selling and which I have used often.

After my last outing with this load I decided to try my old “standby powder” for several different calibres, Tightgroup.

I loaded up some 4.2 gn Tightgroup loads and while accuracy was much better I thought the load felt a bit light so the other day I loaded up just under 150 9mm rounds using a max charge of 4.4 gn powder.

Today I had a bit of time to compare the two loads using a standard drill consisting of:

5 X draw and fire a single shot no time.
Draw and fire 5 shots, no time.
5 X draw and fire a single shot in under 3’seconds.
5 X draw and fire 2nshots in under 3.5 seconds.

The intention of this drill is to fire all A zone hits on an IPSC target at 7.5 and then at 15 meters (with 3.5 and 4 seconds for the timed fire strings) in order to build accuracy. If you don’t get all A zone hits then shoot that string again until you do.

I have shot this drill so often I now start at 10 meters. In order to compare the two loads I decided that what was shot would stand unless the string was so bad. The goal was, the same in competition, 75-80% A hits. I also timed the draw and fire 5 X string in order to get a hit factor to compare.

The results:

First up the 4.2 gn load. The 5 X 2 shot string results were not as good as they should be. of the 10 rounds there were 5 A’s, 4 C’s and 1 “I don’t know where it went”. Obviously a fault on my part so I decided to reshoot that string.

Final result was a score of 110/125 with 80% A zone hits and a 5 shot string hit factor of 2.9639. Most of the timed shots were 2.8 and 3.3 seconds.

Next was the 4.4 gn load. Overall I felt that the load shot much better for me. There were no reshoot strings. Timed strings were under 2.5 seconds and around 2.8-3 seconds for the double shots. The overall score was 117/125 with 88% of shots landing in the A zone. The 5 shot string hit factor was 3.5360. Also apparant was that while the lighter load group was centered to the right in the A zone the 4.4’gn group was centered right in the centre.

I had patched out both targets before thinking to get them boots, so I fired another 10’rounds on the 4.4 gn target the make 35 round groups and took the pics.

Now I know this is not definitive. Had I gotten used to the pistol for the second target after shooting .45 for the last two months? Did my shooting improve as the comparison progressed? And does a .2 gn charge increase, often within the margin of drop to drop of some powder measures, really make such a difference?

I’m not sure either way, but I know which load I’d be more confident shooting out to 35’meters and on Sunday I’ll chrono both loads then shoot the 4.4 gn load in a 48 round Classic Pistol Service Match and compare the score my last one using the Kimber and the 4.2 gn load.

But I think I already know what I’ll be shooting the next time I compete with the Kimber.

[jaymoore]

If you THINK it's better, that's often reason enough. Clears your mind to find that front sight.

[Nevada Ed]

Sometimes a starting load is just that.......
enough to work the action but not enough powder to get a good ES.
.2 more grains of powder might raise the fps a little more but...
it also fills up the case and shrinks the total volume which can help accuracy.
It will also help against a light load that might jam or stove pipe.

Many like to load on the cheap......
however I have found that a lot of starting load,fast powders did
not do well for me in the starting stages.
My 5" 9mm needs most "Copper" bullets to be going over 1010fps
before they start to group all the way up to 1220fps.

I know that 125PF is need for a lot of shooting games but my pistol
likes a 115 and 124 plated at around 129 power factor.
Going low for minimum recoil is not always a choice, if I want accuracy.

You did well on those targets, at that distance.
Tight groups.

[gwpercle]

Confidence in a load can make a big difference. If you believe a load is more accurate and you believe you shoot it better then your shooting will usually reflect that belief .
I have a few pet loads I believe in ...Go with what you believe in.
Gary

[rwsmith]

...about the second target is that if the shots vary, they are in a vertical direction which I think is a lot better than side to side.

Maybe that .2 grains changes the harmonics of the barrel/gun.

Your test was 'real world', but I'd like to see shots off a bench rest to minimize human involvement just to see if the gun is actually shooting better or if you are shooting better.

[Kiwi cop]

Originally Posted by Nevada Ed

Sometimes a starting load is just that.......
enough to work the action but not enough powder to get a good ES.
.2 more grains of powder might raise the fps a little more but...
it also fills up the case and shrinks the total volume which can help accuracy.
It will also help against a light load that might jam or stove pipe.

Many like to load on the cheap......
however I have found that a lot of starting load,fast powders did
not do well for me in the starting stages.
My 5" 9mm needs most "Copper" bullets to be going over 1010fps
before they start to group all the way up to 1220fps.

I know that 125PF is need for a lot of shooting games but my pistol
likes a 115 and 124 plated at around 129 power factor.
Going low for minimum recoil is not always a choice, if I want accuracy.

You did well on those targets, at that distance.
Tight groups.

Thanks Ed.

A couple of points you raise.

For some reason the Hodgdon data site gives me different results every time I visit it. The first time 4.2 gn Titegroup was listed as the maximum 124 gn load. Next time it was 4.4 gn. Today it is 4.1 gn. Go figure!

Because some of my mags are actually .38 Super mags (I bought them as 9mm ones) and can nose dive the first few rounds if they are 9mm length, I load my projectiles out a little. Not to .38 Super length but spitting the difference between the two calibers. They are then reliable in the .38 Super magsstill function in my 9mm ones, but I know that they do lower the pressure and velocities a bit. (My first loading at this length dropped from 134 PF down to 122 with the same powder, weight and bullets),

I like to load to around 130-135 PF, just to provide a buffer above the 125 level. I once had some .45 ACP/200 gn loads chrono at 158 PF in a competition so ended up shooting ".45 minor" all weekend.

Finally, thanks for the comment about the targets. I ran out of time yesterday to try them out past the 10 meter mark but Sunday's match is shot at 10 and 25 yards so will see what happens then.

[Kiwi cop]

Well this morning I got to the range an hour early and set up the chronograph.

First up were the 4.2 gn loads.

Please remember though that I load to an OAL of 1.154" due to using some .38 Super magazines. Standard 9mm OAL will give higher velocities due to less case capacity after the bullet is seated.

First 3 shots averaged 1135 fps/140.7 PF
The next two shots recorded lower velocities. The 5 shots averaged 1125 fps/140.1 PF.
Highest velocity was 1143 and the lowest was 1108.
Taking out the lowest velocity gave a 4 shot average of 1130 fps/140.1 PF, right in the middle of the 3 and 5 shot strings..
Taking out the highest and lowest gave 1126 fps/139.6 PF

Then it was on to the 4.4 gn loads.

First 3 shots averaged 1110 FPS/137.6 PF (the third shot was a stinker, the lowest velocity for this load).
The 5 shot average was 1117 fps/138.5 PF
Highest velocity was 1150, lowest 1078, the only shot to drop below 1100 fps.
Removing that lowest shot gave me a 4 shot 1127 fps/139.7 PF.
Taking out the highest and lowest velocities resulted in 1119 fps/138.7 PF

So really there is no actual difference in velocities between the two loads.

On to the 48 round Classic Pistol match and I scored the exact same score as I did last time out when I was shooting the old WAP loads.

The thing is this match is fired gun in hand from the 45 degree position and there is provision for establishing sight picture/grip adjustment. I still feel that when drawing from the holster these loads outperform, for me anyway, the WAP loads. And I have a bit more confidence in the 4.4 gn load over the 4.2 one.

After the match was over I set an IPSC target up at 15 meters (it's been a while since I've shot a drill at this distance, lately it has been 10 - 12 metes) and ran 5 X draw and double shots. Except for two shots that went high and right (1X D and the other a C) due to a bad grip on the draw (it happens) all the other shots were well entered with 7 out of the remaining 8 in the A zone (overall 70% A zone shots). And while the timer was set for a 4 second PAR, most of the double shots were in 3 - 3.2 seconds (I need to slow it down a bit, so used to 10 meter 3.5 second PAR).

I then drew and fired 10 rounds as quick as I could acquire a decent sight picture. Total time was 7.1 seconds for a hit factor of 5.3521.

5 rounds A zone, 4 rounds C zone with a low hit in the D. I could probably take another 2 seconds on this string and still record a hit factor above 5.

Final verdict, I think I'll stick with Tightgroup and a charge of 4.4 gn in this pistol.