MP-431-256 Penta vs reg vs small pin accuracy test

[Shuz]

Have any of you compared accuracy with the 3 different pins furnished by Miha with his 431-256HP?

In another thread in this forum, I describe how my experiments with 4 different .44 mag revolvers and the MP431-256 regular sized hole boolits that had the holes enlarged with an MP-433-300HP top punch gave groups that were at least twice the size as boolits sized with the top punch that came with the MP-431-256 mould. Just because I was curious, no other reason, I was trying to see if I could make a hollow point that was a little smaller than the Lyman 429640 Devastator.

My conclusion is that my sizing set-up using the MP-433-300 top punch in my old Lyman 45 is not giving me concentric "enlarged" boolits.

Now the quest is to see which of the 3 different pins that came with my 431-256HP mould gives the most accurate boolits, or is there any difference at all? Inquiring minds wanna know!

[44man]

As I said, what happens at the forcing cone? Those large HP's might get mashed. I doubt it is the sizing punch.

[Shuz]

Some preliminary testing of the small hollow point vs the penta hollow point shows me that I need to re-think my testing procedure. I had been testing 5 shot groups against each other, one after the other. Since the groups were in the 2 to 3 inch catagory I was not pleased with either style. Then on a whim, I decided to fire 2/ea 5 shot groups with the penta holes and the second group was much tighter than the first. I found this strange since I observed absolutely no leading after any of the 5 shot groups. Evidently(?) a "wash" may develop that I can't detect, but does have an effect on accuracy? Next time out I will fire many 5 shot groups with the same boolit before moving onto a different hole configuration. This leads me to wonder if the "enlarged" hole vs the regular pin hole testing that I reported on in another thread, needs to be redone with the same procedure?

[Larry Gibson]

Some preliminary testing of the small hollow point vs the penta hollow point shows me that I need to re-think my testing procedure. I had been testing 5 shot groups against each other, one after the other. Since the groups were in the 2 to 3 inch catagory I was not pleased with either style. Then on a whim, I decided to fire 2/ea 5 shot groups with the penta holes and the second group was much tighter than the first.............

The disparity between 5 shot groups of the same load may simply be that the sample size of each is not sufficient. Could very well be both groups fall within the actual accuracy capability of the load. This is why testing with a 10 shot group give a greater surety of what the accuracy potential is. I test with either 10 shots or 12 (twice around the cylinder) with my revolvers because of this. Even shooting multiple 5 shot groups does not really give as good a surety as one ten shot group. The multiple five shot groups can but you have to not make sight adjustments and then over lay the groups with the point of aim and the lateral and vertical planes of the targets coincidental to get the total actual group size. The "average" of the groups sizes or even just the largest group size of one of the five shot groups many times still does not give the surety that a single ten shot group will. The same applies to testing for velocity or psi. That is the reason SAAMI uses the 10 shot test string.

Using an insufficient test sample size many times leads us to erroneous conclusions.

Larry Gibson

[tomme boy]

Test the five shot groups out of the same hole on the cyl. Do that for each hole. That will tell you the accuracy potential of the gun. Your going to find that one of the holes is way more accurate than the others. Some of the revolvers I have tested were like this anyway. When I hunted deer with my 357 mag. I wanted to make sure the first shot went where it was aimed.

[Shuz]

As always Larry, good advice. Next go around I will fire 10 or 12 shot groups. I got used to putting only 5 in the cylinder from my old IHMSA days and still have the habit.

[Echd]

While I have not tested it in a manner as clinically stringent in its details as I would like to make a firm assertion, among 4 molds I have with penta points i have noticed either equivalent or worse accuracy in all of them using the pentas over regular HPs. I cannot comment on shallow vs deep because I only have molds with one set of reg pins.

I have tested my 360-156, 452-200, 356-125, and a .44 I can't remember offhand. In the same guns it has almost always shown a tendency towards the regular pins over pentas. I've never had better consistent results with pentas, although occasionally a "lucky group" might be better than an average one from regular pins.