I did load developement for my M&P pistol with the 9mm Storm Lake barrel. I loaded 4, 4.5, and 5 grains of powder. 5 g was definitely the most accurate, however I was worried about possible pressure signs I was seeing in the primer. The load is within max per 2 different load manuels. Accuracy was significantly decreased at 4.5 g. What say you OB?

I used to get those marks on primers from three different M&Ps that I no longer own. It is normal based on the research I did. Check some factory ammo too. I bet you get the same marks around the striker indentation.

I do not notice it as bad on the loads I had under 5 grains and also do not notice it as much on factory ammo I have shot.

Have you tried loading them with a little longer overall length? That could reduce the pressure.

I get those same striker dents on the factory ammo i shoot in both my M&P compact and pro.

If you don't see it on factory, and you don't see it on reduced loads, then yes, they are the beginnings of pressure signs. I wouldn't load any hotter, but if the gun ate them, and it grouped best, I would not have issue shooting them at that load.

I am assuming you shot these on a hot day. On colder days, the signs will likely disappear. If the temps were more mild, you will have worse signs on a hot day.

Powder? Projectile? Primer? OAL?

At first blush, they dont look like anything to get concerned about. I have heard the M&P can leave funny pin marks, but i have no experience with one.

striker fire pistols typically leave this imprint on the primer. As previous posters have suggested, please give component info and load data.

Also, .5 jumps on a 5 grain max is a lot of jump. You might try .2 grain intervals and see if you find a better grouping load than even the 5 gr.

9mm
CCI small pistol primer
5g Unique powder
Berry's thick plated 115g RN Hollow base bullet
I don't remember C.O.L.

quote:

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CCI small pistol primer
5g Unique powder
Berry's thick plated 115g RN Hollow base bullet
I don't remember C.O.L

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this is a similar (but not equal comparison) from alliant:
http://www.alliantpowder.com/reloaders/RecipePrint.aspx?gtypeid=1&weight=115&shellid=23&bulletid=25&bdid=28
I think you are going to be ok as long as your OAL isn't less than 1.125"

There are a couple things to be aware of with that projectile. First is it's plated. Plated projectiles do not handle max charges as listed by most powder manufactures. Be cautious, and try to find cast/recommended load data from the projectile vendor. Next, the shape of the bullet can drastically alter your OAL. If you decrease the OAL, you will increase the chamber pressure, and that could be hazardous. RN bullets will ride feed ramps differently than HPs, so always check headspace on the firearm you are about to load for.

The only thing I would say is that the charge weight seems a touch steep for what amounts to a cast lead projectile.

Plated projos should be loaded to cast lead data - the jacket is not thick enough to sustain pressures present with jacketed projectiles, and the higher pressures and heat can lead to leading in your barrel even with the plating.

Reloader's Nest didn't have anything for plated or cast lead with Unique, and unfortunately Alliant's online resources are pretty crappy IMO.

A good rule of thumb is to stay at 10% below jacketed loads for the same bullet weight with plated or cast projectiles, keeping in mind that every firearm is a bit different.

Thanks for the replies. I do understand about the Berry's projectiles. I was having a hard time finding cast loading info though. The max load for similar not cast bullets was around 6g so I felt 5g would be an acceptable decrease to account for the plated bullet. My C.O.L. was 1.125.

Did you hand measure each charge? Kind of a PITA, but I go through the process of weighing each charge in the *developement* of new load. If I don't get the results I theorize I should get on the range, at least I can eliminate weight variations as a culprit. Scratch that unknown off the list.

Progressive or single stage loader?
Your experience may vary, but I notice my progressive seems to throw with more variation with some powders.

Did you crimp?

Weighed each charge twice. Once on a lyman charemaster and then on a dillon digital scale. I loaded each bullet on my Dillon 550. I use it as a single stage press though for this type of stuff. Once i figure out my load I will set it up to run progressive. I also check each bullet with calipers for OAL and a case guage for proper seating. I know, it sounds very anal but I want to make sure in training and competition that I can't blame the bullet. Light crimp on each bullet.

[This message has been edited by TxAggie72 (edited 5/27/2014 3:38p).]

Your powder load on the high end is within spec - Lyman had a min load of 4.5 grains and a max load of 5.7 grains for a 115 cast lead. (#358345 profile, #2 alloy composition, .997" OAL. (Above i thought it was too high, but it ended up being the low end that was out of range)

Now the BC is probably different given the different geometry of the projectile and a round nose design, but it isnt going to be such a difference that you are in a danger zone.

Your starting charge was a little low, which generally is not a huge concern. However, under the right conditions, a short charge can be as bad as an overcharge, so keep that in mind. Too much case room can, on rare occasions, allow the powder to burn outside the pressure range - it can burn too fast and lead to a KABOOM. Not likely, but possible.

Both of my loads are with Universal, though my next batch will be with Unique. I will be sticking with the ranges above and tweaking as necessary.

[This message has been edited by schmellba99 (edited 5/27/2014 8:34p).]

[This message has been edited by schmellba99 (edited 5/27/2014 8:36p).]

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Now the BC is probably different given the different geometry of the projectile and a round nose design, but it isnt going to be such a difference that you are in a danger zone.

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Lyman typically has good cast data, so that should be good. As long as you don't decrease the published OAL, you should be good. I forget the formula (probably somewhere on reddit.com/r/reloading) but for each hundredth you decrease, you increase ?10k in chamber pressure.

but for each hundredth you decrease, you increase ?10k in chamber pressure.

This sounds high, considering many of the older handgun loads we shoot are in the 12k-15k range.

I think 10k is high - maybe closer to 1k?

Even at 1k, a setback of a couple of tenths (would be pretty unusual, but not out of the realm of possibility) can cause a significant % increase, so it's definitely something you need to pay attention to.

It also is going to significantly depend on what type of cartridge you are shooting. Something like a 9mm or .45 ACP that has a relatively small case volume and less wiggle room is going to have significantly different reactions to changes in case volume versus something like a .223 or .30-06, which has a pretty substantial range in case volume.

Keep in mind as well that temp plays a role, as does neck tension, crimp/no crimp, magnum versus standard primer, chamber geometry and dimensions and about a thousand other things. Reloading is not an exact science by any stretch, and the good thing is that generally it takes a culmination of a lot of things gone wrong to cause issues. Otherwise we'd be in a lot of trouble collectively.

lol yes, 10k is more than likely wrong. I don't remember the source - nor the equation. but I do believe we get the point that decreasing OAL increases chamber pressure