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9mm. Likely pressure increase if I seat 0.015” deeper?


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Long story so the briefest version is I need to seat a loaded lot of rounds that’s near max about 10 to 15 thou deeper to keep away from the lands.
I figure it’ll make little difference but I’m asking you guys to be sure.  

 

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Try a small batch first and evaluate after shooting.

 

Were the loads worked up at the present OAL?

 

Jacketed or plated bullets?  Plated are generally more forgiving.

 

If the bullets are presently contacting the rifling, giving them some distance off the rifling will likely be beneficial.

 

Edited by Guy Neill
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I did that a few years ago and couldn't bring myself to shoot them after reading the warnings in reloading manuals.  I found, for me, the best bet was to pull them and start over again.  I bought a collet pullet and it really worked great.  I reloaded the brass and bullets and saved the powder.

 

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I posted about this same thing a while ago. If you search you might find it. I actually did it and had no problems. One article I read said to look at all the bullet weights that your using in manuals. Find the minimum max load for that bullett. As long as you don’t go over the fps. for that load you can do what you want. Example a 124 jhp. Your using n320, go and look up all the max loads for that bullet weight , doesn’t mater if it’s jhp. Say the max fps are 1080, 1100, 1120, 1050, you take the 1050 which is the minimum max load of all the bullet weights. Go ahead and shorten a few of your loads, chrono them as long as your under the 1050 your gtg. Now the disclaimer. This worked for me, but may not work for you. You need a chrono to do this. Of course the safest way is to just pull them.

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6 hours ago, McHaggis said:

Long story so the briefest version is I need to seat a loaded lot of rounds that’s near max about 10 to 15 thou deeper to keep away from the lands.
I figure it’ll make little difference but I’m asking you guys to be sure.  

 

 

What is your load data?

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Minor with a slow powder will make little difference.  Minor with a fast powder will see a significant increase in pressure.  Major, no way.

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I'd say the biggest factor is the gun you are shooting it in.  Example - At a match I dropped a loaded 9 major round on the ground, another shooter picked it up.  He was shooting a plastic gun, you know one of those tupperware specials, long story short on the next stage we spent 20 minutes looking for the trigger parts to his gun. 

 

A real answer could only come when you provide the current OAL the powder used and the amount, along with the bullet type and weight.   

 

When I was shooting 200 grain 40 over Clays the OAL was critical, and yes I blew up a few cases, then got smart and went to 185gr and a different powder.  9 mm is pretty darn tuff as proven by 9 major, on a cold morning at the LA Gator match I won the crono stage at 189 pf.  I didn't shoot well till it warmed up later in the day.  Depending on the powder even the temp can play hell on pressure.

 

I've had to do the same thing before, my Hornady L&L makes it easy, just remove the powder measure and the sizing die and run them thru.  The rounds fit the SIG but stuck in the CZ.  

 

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Current OAL is 1.128”. I have about 80 loaded and almost all pass the plunk test. The odd one doesn’t. 
I’m using a 145gr coated lead RN in a CZ S2 with 2.84gr APS350.  This is a fast powder and the load is around 128PF. The load was worked up and I’ve shot off over 1000rds with no problems. 
It might just pay to leave them as is as I know they are fine as it. Load development when up to 2.9gr with no pressure signs. 
 

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2 hours ago, McHaggis said:

Current OAL is 1.128”. I have about 80 loaded and almost all pass the plunk test. The odd one doesn’t. 

 

The odd ones may not be due to OAL.  If you are having a wide variation in OAL, just push the long one back to normal.  If it is a slight case bulge, that's a different story.

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don't overthink this. max book load is unbelievably conservative. I have shortened 100's of bullets for the same reason, and I don't give it a second thought. going from 1.13 to 1.11 will give you a few extra pf, similar to an extra tenth of a grain of powder. You may be able to feel it if you pay close attention, but it's not going to be dramatic.

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If you think the maximum loads are conservative, point the finger at SAAMI.  All the reloading manuals I've worked on had the maximum loads at the SAAMI Maximum Average Pressure.

 

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7 hours ago, McHaggis said:

Current OAL is 1.128”. I have about 80 loaded and almost all pass the plunk test. The odd one doesn’t. 
I’m using a 145gr coated lead RN in a CZ S2 with 2.84gr APS350.  This is a fast powder and the load is around 128PF. The load was worked up and I’ve shot off over 1000rds with no problems. 
It might just pay to leave them as is as I know they are fine as it. Load development when up to 2.9gr with no pressure signs. 
 


I looked up the manufacturer recommendations and the max is really low and slow for APS350.  I still don’t believe you will have any noticeable pressure changes with your load because there are too many variables to measure. Just a variety of head stamps will have different case volumes. 
 

However, based on min and max recommendations I would go with a different powder, if you have a choice.  It would be very difficult to increase the velocity of you bullets if you needed to for accuracy and assurance you will make PF.

 

Just my thoughts. 

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I am going to change powders and have 3 I’m looking at sorting loads for.  I was never real happy with this load but it has shot fine. I’m going to try ADI AP50, AP70 and W231 all with 125gr coated lead. Just waiting on a magnetospeed v rail adapter so I can shoot them.  And also waiting to get the cast off my foot so I can walk!  

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As a general rule, when dealing with a new bullet profile I size a case and set a bullet longer than I intend to load being sure not to crimp. (and no powder or primer).   Then I take it and chamber it in the gun I intend to shoot it in.   Chambering will shorten it to the longest length that the gun will accept.  Measure it then load 3 more dummies -.01 shorter and make sure they fit and dry cycle thru the gun.  If it is all good and it feeds well that is the starting OAL.  If it won't fit in the gun then it don't matter what the load table says.  With that I consider the Load data just to make sure I'm not way over spec.  It is that OGIVE thing, each bullet profile is different, I had to adjust OAL slightly going from Montana Gold 124gr JHP to Precision Delta 124gr JHP, the precision delta is slightly larger in diameter, just enough my carry gun wouldn't eat it, the open gun no problem.(minor load, all the majors are 1.165-1.175).

 

In your case if you are satisfied with the shorter OAL and you know it will work with the gun, you can shorten them, albeit since they are coated it will cut the coating, no big whoop you will get a little leading which can be easily remedied by shooting some copper jacketed bullets, or Flitz and elbow grease.

 

w231 is the pretty twin of WST great for 40 not so much for 9 mm.  The best powder I found for minor 9 mm is N320, somewhere around 3.2gr with your coated bullet should put you in the minor pf.   That said in these days it is more what you can get than what you want to shoot.  I never liked 147gr felt sluggish, 135gr coated is my favorite for minor 9, but you shoot what you can get now 115gr FMJ for now, I bought enough the mailman hates me now. 

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13 hours ago, superdude said:

 

Explain.

what explanation is needed? the max loads have to be safe even in crappy unsupported barrels in plastic guns, and they have to have a safety margins built in everywhere there could be a tolerance. case thickness/volume, powder-measure accuracy, scale accuracy, bullet weight, etc....

 

fwiw, when working up a self-defense load a few years ago (using n340 and 124gr xtp), i found that shortening the OAL from 1.12 to 1.08 resulted in a 30fps increase in velocity. Significant, but not enough to go from safe to dangerous imho.

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5 hours ago, motosapiens said:

what explanation is needed? the max loads have to be safe even in crappy unsupported barrels in plastic guns, and they have to have a safety margins built in everywhere there could be a tolerance. case thickness/volume, powder-measure accuracy, scale accuracy, bullet weight, etc....

 

The question is why you said that max book loads are conservative. Do you mean max book loads are not loaded to max pressure specs? Or that max SAAMI pressure itself is conservative compared to what a load can be loaded to? - meaning that one can load past max book loads.

 

As Guy Neill notes, max book loads are often at max SAAMI pressure.  The ADI load data for 9mm looks to be up to SAAMI max pressure.

http://www.adi-powders.com.au/pistol/9mm-luger

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1 hour ago, superdude said:

 

The question is why you said that max book loads are conservative. Do you mean max book loads are not loaded to max pressure specs? Or that max SAAMI pressure itself is conservative compared to what a load can be loaded to? - meaning that one can load past max book loads.

 

As Guy Neill notes, max book loads are often at max SAAMI pressure.  The ADI load data for 9mm looks to be up to SAAMI max pressure.

http://www.adi-powders.com.au/pistol/9mm-luger

 

 

the link you provided shows that very few of the ADI loads claim to be at max pressure. At any rate, my point still stands. The max pressure specs have to have a significant safety margin or crappy metallurgy, unsupported chambers, etc.......  

 

 

Edited by motosapiens
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10 hours ago, CocoBolo said:

As a general rule, when dealing with a new bullet profile I size a case and set a bullet longer than I intend to load being sure not to crimp. (and no powder or primer).   Then I take it and chamber it in the gun I intend to shoot it in.   Chambering will shorten it to the longest length that the gun will accept.  Measure it then load 3 more dummies -.01 shorter and make sure they fit and dry cycle thru the gun. 

This is what I normally do and hence why 95% of them fit. But it looks like I’m right at the lands so there’s little room for margin. 
I might just shoot these and load a few at 1.115” with 2.80gr and crono them to see how they look and go from there. 
 

Could this be the reason why when shooting a group at 15 yards l can get 9 in a 2.5” group but 1 is 6-8” low?

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10 hours ago, CocoBolo said:

 

w231 is the pretty twin of WST great for 40 not so much for 9 mm.  The best powder I found for minor 9 mm is N320, somewhere around 3.2gr with your coated bullet should put you in the minor pf.   That said in these days it is more what you can get than what you want to shoot.  I never liked 147gr felt sluggish, 135gr coated is my favorite for minor 9, but you shoot what you can get now 115gr FMJ for now, I bought enough the mailman hates me now. 


 

Powder here is also very hard to get. I’ve read many posts advocating the use of w231 in a 9mm so I got some as it was briefly available. 
I’m expecting better results with the AP50, as it’s a little quicker, so it should give better results but that’s why we test. 
I’d prefer Sports Pistol but it’s almost as rare the common sense is in the Biden administration and I have never seen it here. Here, being the bottom of New Zealand. 

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51 minutes ago, McHaggis said:

Powder here is also very hard to get. I’ve read many posts advocating the use of w231 in a 9mm so I got some as it was briefly available. 
I’m expecting better results with the AP50, as it’s a little quicker, so it should give better results but that’s why we test. 
I’d prefer Sports Pistol but it’s almost as rare the common sense is in the Biden administration and I have never seen it here. Here, being the bottom of New Zealand. 


I’m so sorry. While Prime Minister Arden has stopped the COVID from invading NZ, she has also stop a whole lot of trade.  
 

I would recommend you look at the powder burn rate charts and pick the one available to you which has the closest match to Titegroup, N320, and Sport Pistol.

 

Biggest problem with some in the range have a very low density and may fill the brass more than you need. 
 

The hobby is becoming finding reloading components more than the shooting. 😪

 

 

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Yes. Sadly we have a Prime Minister that is hell bent on driving us to ruin. The lefty’s have just started and the future looks bleak at best. 
The AP50N is in that burn rate I think. I can’t find a current chart that lists all the new powders and most charts don’t list the ADI powder at all. 

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