Bullet Length

[donut1953]

One of my biggest gripes with reloading manuals is they never seem to plublish the oal of the bullet they use for their data. For many years I have used Precision Delta 124 grain JHP which measure around .586. Over the years I have worked up loads using Power Pistol and CFE Pistol and found my COL at 1.100 is a length that fit all my 9mm pistols.

Recently I purchased some 124 grain Nukes from RMR and they measure apprx .542. What a difference in bullet profile from the Precision Delta. I found I have to go to a COL of 1.065 to pass the plunk test in all my 9mm.

Here are a couple questions that maybe people can help me with. Since I have to shorten my COL to 1.065 and everything else (powder/primer/case) stays the same, am I safe to assume since the math tells me I have .009 more space inside the case I should be go to go? That said I will probably drop down .3 tenths on the powder and work back up just to be safe, but I would like to see what people think about just loading base on bullet length. Also is there any reason why powder manfactures or bullet manfactures do list the bullet length in their reloading info?

 

[mdi]

Over thinking .009" less case capacity? I would just use "Reloading 101" methods; whenever a component is changed do another load work up, from starting load data. When I started using RMR 124 JHPs I noticed they were very close to Nosler 124 gr bullets so I started with Nosler data...

 

[AJC1]

When I think reloading I think cars. If you have the same cylinder volume after swapping pistons the carburetor won't need adjustment. .008 more under bullet volume will decrease pressure so the same charge will produce less speed. Barring the mental exercise the procedure says when you change components you work back up. That can easily be done in 5 or 10 rounds so it's not the huge deal it's made out to be.

 

[kalielkslayer]

Damn. I load all of mine at 1.140. Max is 1.169. They all pluck in Glocks and Springfields.

a couple of thousands wouldn’t change anything for me, but I would do a function test in all the guns before I ran a bunch.

 

[lordpaxman]

One of my biggest gripes with reloading manuals is they never seem to plublish the oal of the bullet they use for their data.

It’s the reason I have a spreadsheet with the caliber, bullet, bullet OAL, and each barrel’s MAX COL. I believe somewhere in this forum, maybe @LiveLife post, there was a bullet OAL chart with a number of different MAX COLs based on guns.

Since I have to shorten my COL to 1.065 and everything else (powder/primer/case) stays the same, am I safe to assume since the math tells me I have .009 more space inside the case I should be go to go?

Ah yes grasshopper, but everything else is not the same. It’s a different bullet. You math is correct, but, even though both bullets are FMJs, they are not the same. It’s very likely it won’t make a huge difference but I’d back down a tenth or few. If you had mentioned Titegroup, the hairs on the back of my neck would be rising…

 

[black mamba]

Unfilled case capacity will lower pressure, but other factors like bearing surface and diameter of the bullet can change things, too. Drop down 5% on your powder charge and work back up to be safe.

 

[LiveLife]

Since I have to shorten my COL to 1.065 and everything else (powder/primer/case) stays the same, am I safe to assume since the math tells me I have .009 more space inside the case I should be go to go? That said I will probably drop down .3 tenths on the powder and work back up just to be safe

Yes, for high pressure 9mm with small internal case volume, small changes in OAL/bullet seating depth by few thousandths can significantly affect pressure by several thousand PSI (See bottom of linked post) - https://www.thehighroad.org/index.p...-and-discussions.778197/page-11#post-12503881

When my max/working OAL/COL is shorter (deeper bullet seating depth) than published load data for same bullet length, I will reduce start/max charges by .2-.3 gr.

Also is there any reason why powder manfactures or bullet manfactures do list the bullet length in their reloading info?

Yes, to calculate the case powder fill (See bottom of linked post) - https://www.thehighroad.org/index.p...er-target-published-load-data-for-9mm.870180/

BTW, list of commercial bullets by caliber - https://www.jbmballistics.com/ballistics/lengths/lengths.shtml

Another list - https://www.accurateshooter.com/ballistics/bullet-database-with-2900-projectiles/

124 grain Nukes from RMR

It’s a different bullet. You math is correct, but, even though both bullets are FMJs, they are not the same

Yes. Also, 9mm bullets can come in different sizing from .354", .355" to .3555" and .356" so depending on case wall thickness, neck tension and bullet setback can add to reloading variables to affect chamber pressure.

For accuracy, ultimately what matters is the "chambered OAL" after any bullet setback; and not "finished OAL".

BTW, here's myth busting done on 9mm neck tension and bullet setback - https://www.thehighroad.org/index.p...neck-tension-and-bullet-setback.830072/page-4

FYI, RMR "Nuke" and MPR JHP bullet nose profiles/ogive are derived from RN with tip cut off (For more reliable feeding) - https://www.rmrbullets.com/shop/bullets/pistol/9mm-355/9mm-124-gr-rmr-jhp-mpr-nuke/

I believe somewhere in this forum, maybe @LiveLife post, there was a bullet OAL chart with a number of different MAX COLs based on guns

https://www.thehighroad.org/index.p...col-for-reference.848462/page-2#post-12249361

 

[donut1953]

Damn. I load all of mine at 1.140. Max is 1.169. They all pluck in Glocks and Springfields.

a couple of thousands wouldn’t change anything for me, but I would do a function test in all the guns before I ran a bunch.

Are you referring to the RMR Nukes 124 Grain JHP? I ran a couple at 1.100 and they would not even pass the plunk test in my Glock 48. I have quite a few 9mm pistols and found my tightest chamber is my Canik TP9 SC. In order to pass the plunk test in the Canik I had to seat to 1.065.

 

[donut1953]

to livelife and to all others thank you for all the info and suggestions.

 

[LiveLife]

Precision Delta 124 grain JHP ... found my COL at 1.100 is a length that fit all my 9mm pistols.

124 grain Nukes from RMR and ... What a difference in bullet profile from the Precision Delta. I found I have to go to a COL of 1.065 to pass the plunk test in all my 9mm

Are you referring to the RMR Nukes 124 Grain JHP? I ran a couple at 1.100 and they would not even pass the plunk test in my Glock 48. I have quite a few 9mm pistols and found my tightest chamber is my Canik TP9 SC. In order to pass the plunk test in the Canik I had to seat to 1.065.

Yes, due to bullet nose profile/ogive that expands out the part above the bullet base, RMR JHP needs to be loaded shorter than more typical JHP profile that can be loaded longer.

And also depends on the barrel's leade length.

Older RMR JHP on the left that has nose profile similar to Gold Dot HP and new RMR MPR/Nuke on the right that need to be loaded shorter OAL - https://www.thehighroad.org/index.p...col-for-reference.848462/page-2#post-12249361

• SIG P320 X5/Bar-Sto Match 5" Barrel - 1.030"
• Taurus PT-809 - 1.030"
• M&P Shield 9mm EZ - 1.040"
• Glock 23/LW Conversion barrel - 1.040"
  
• Glock 22/TK Conversion barrel - 1.055"
• Kimber Micro 9 - 1.060"
• SIG P938 - 1.060"
• Taurus PT-111 G2 - 1.070"
• Canik TP9SFX - 1.070
• HK VP9 - 1.080"
• SIG P320 X-5 - 1.100"
• M&P Shield - 1.105"
• Glock 23/KKM conversion barrel - 1.115"
• Beretta 92FS - 1.125"
• Hi Power Mark 2 - 1.125"
• SIG P226 Legion SAO - 1.150"