Zero 165 JHP poorly grouping - MP-Pistol Forum

Zero 165 JHP poorly grouping

This is a discussion on Zero 165 JHP poorly grouping within the MP Reloading forums, part of the Smith & Wesson MP Forum category; Just picked up about 2,000 of these and am having trouble getting them to group. I'm using mixed headstamp cases with CCI-500 primers lighting HP-38 ...


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Old February 5th, 2015, 06:43 AM   #1
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Zero 165 JHP poorly grouping

Just picked up about 2,000 of these and am having trouble getting them to group. I'm using mixed headstamp cases with CCI-500 primers lighting HP-38 powder. All of these loads seem to group around 6" or more from my M&P 40fs from a sandbag rest under my wrists. The loads I've tried are:
4.8 gns gives 919 ave. fps with 23 SD
5.0 gns gives 938 ave. fps with 5 SD
5.2 gns gives 953 ave. fps with 10 SD

If you aren't familiar with Zero JHPs, they are true copper jacketed HPs - not plated. The 5.2 gns of HP-38 should be near the max if my research is correct and the speeds I'm getting seem about right.

Prior to these bullets, I was using Berry's plated 180 gn FP. I also used HP-38 for these and got groupings around 4" or less. My Berry's load was:
4.1 gns for 779 ave. fps with 19 SD

Just to make sure my pistol didn't take a dive, I loaded up some WWB 165 gn and both groups I shot with these came in under 3 1/2" so the gun is working as it should. By the way, the WWB loads came in at 1050 ave. fps with an SD of 10.

So any ideas? I feel kind of stupid here and I think I'm missing something but can't see the forest for the trees. I fully expected my Zeros to give very good groups but I'm not realizing that.
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Old February 6th, 2015, 07:14 PM   #2
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One assumes you are shooting .40 S&W?
MAX load could be from 5.3-6.3gn, depending on gun and exact components.
I have not found 231/HP38 to be all that accurate in .40, but you should get better than 6" (at whatever distance you are shooting at) if a plated bullet will do 4". Zero are, in general, very accurate if not the most accurate bullets you can find.
The best I have done with 231/HP38 is with 4.2-4.5gn. That gets my guns under 3" at 25 yards easily.
In my .40s, powders faster than AA5 have not done well in terms of accuracy. AA5 has been the most accurate powder, with Silhouette running close second (followed by Power Pistol and Unique). However, having a wide selection of powders to use is rare nowadays.
First, I would be sure the barrel is completely clean.
Second, I would check the diameter of the bullets and make sure nothing is off there. I have found undersized jacketed, plated, and cast lead bullets before.
Third, I would load as long as possible to fit magazine and barrel (>1.145" COL). Most of my loads range from 1.153-1.203".
Finally, some guns and bullets just don't get along.
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Old February 7th, 2015, 02:50 AM   #3
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I load far more 155gr than 165 but found hp-38 was more accurate with heavier powder loads than lite loads . . Both loads are as long as the chamber and mag will allow . I have since changed to Missouri coated swc and find they shoot very well for me. My M&P likes the longer lengths . and closer to max powder over lite loads.

With mixed brass a tight SD can be far more about luck . My mixed brass SD run closer to 25 to 35 depending on what mix I of brass tested . So I know longer check mix brass.

You may want to change the OAL to see what that changes .
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Old February 7th, 2015, 05:38 AM   #4
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Thanks for the responses. I should have clarified that I am runing 40S&W loaded to about 1.130" +/- because that seems to be toward the upper limit of what my mags can reliably handle.

I haven't tried any loads lighter than 4.8 gns of HP-38 but maybe they will group better. I'll have to run a ladder of these to see if the grouping improves. I was thinking because I got reasonable groups from the WWB loads (WWBs are plated) and mine were substantially softer that maybe I had to go up in power but maybe the Zeros do better with lighter charges.
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