Variance In Pistol Bullet Length By Manufacturer ?

[oldguyguns]

Was wondering how much the bullet length (not cartridge OAL) varies by manufacturer for 380 or 9MM bullets. Going to measure some as I start reloading again but thought some of your may know. Particularly interested in bullets from which manufacturer are the most uniform. Use mostly FMJRN from Hornady.

 

[trophyhunter]

The differences are substantial between manufacturers in bullets of the same weight and profile with different lengths, enough to make a huge discrepancy in the amount of pressure generated in 9mm rounds as the longer bullet seated to the same COL as a shorter one using the same propellant charge can ramp pressure up considerably with some popular choices in 9mm powders.

Here's an example using QL predictions to show two bullets I have on hand loaded with an identical charge of 6.7 grains of AA#5, using the pressure ceiling of 35,000 psi for Sammi 9mm the longer Sellier-Bellot using the same 115g FMJ-RN profile and powder charge produces 14,898 more psi seated to the same depth and COL.

Cartridge          : 9 mm Luger (SAAMI)Bullet             : .355, 115, Hornady FMJ/RN ENC 35557
Useable Case Capaci: 8.978 grain H2O = 0.583 cm³
Cartridge O.A.L. L6: 1.120 inch = 28.45 mm
Barrel Length      : 4.0 inch = 101.6 mm
Powder             : Accurate No.5


Predicted data by increasing and decreasing the given charge,
incremented in steps of 2.0% of nominal charge.
CAUTION: Figures exceed maximum and minimum recommended loads !


Step    Fill. Charge   Vel.  Energy   Pmax   Pmuz  Prop.Burnt B_Time
 %       %    Grains   fps   ft.lbs    psi    psi      %        ms


-20.0   63     5.36   1009     260   20440   4476     78.2    0.511
-18.0   64     5.49   1032     272   21607   4640     79.4    0.499
-16.0   66     5.63   1056     285   22829   4805     80.5    0.487
-14.0   67     5.76   1080     298   24109   4969     81.6    0.474
-12.0   69     5.90   1104     311   25447   5132     82.7    0.462
-10.0   71     6.03   1128     325   26849   5295     83.7    0.450
-08.0   72     6.16   1151     339   28315   5458     84.7    0.438
-06.0   74     6.30   1175     353   29850   5619     85.7    0.427  ! Near Maximum !
-04.0   75     6.43   1199     367   31457   5779     86.7    0.417  ! Near Maximum !
-02.0   77     6.57   1223     382   33139   5938     87.6    0.406  ! Near Maximum !
+00.0   78     6.70   1246     397   34900   6095     88.5    0.397

Cartridge          : 9 mm Luger (SAAMI)Bullet             : .355, 115, Sellier-Bellot FMJ SB31917
Useable Case Capaci: 7.498 grain H2O = 0.487 cm³
Cartridge O.A.L. L6: 1.120 inch = 28.45 mm
Barrel Length      : 4.0 inch = 101.6 mm
Powder             : Accurate No.5


Predicted data by increasing and decreasing the given charge,
incremented in steps of 2.0% of nominal charge.
CAUTION: Figures exceed maximum and minimum recommended loads !


Step    Fill. Charge   Vel.  Energy   Pmax   Pmuz  Prop.Burnt B_Time
 %       %    Grains   fps   ft.lbs    psi    psi      %        ms


-20.0   75     5.36   1079     299   27129   4467     81.6    0.458
-18.0   77     5.49   1105     313   28862   4624     82.8    0.445
-16.0   79     5.63   1131     328   30695   4779     83.9    0.432  ! Near Maximum !
-14.0   81     5.76   1157     344   32632   4933     85.0    0.420  ! Near Maximum !
-12.0   83     5.90   1183     359   34681   5086     86.1    0.408  !DANGEROUS LOAD-DO NOT USE!
-10.0   84     6.03   1209     375   36850   5237     87.1    0.397  !DANGEROUS LOAD-DO NOT USE!
-08.0   86     6.16   1235     392   39147   5385     88.1    0.386  !DANGEROUS LOAD-DO NOT USE!
-06.0   88     6.30   1261     409   41579   5531     89.0    0.376  !DANGEROUS LOAD-DO NOT USE!
-04.0   90     6.43   1287     426   44158   5675     90.0    0.366  !DANGEROUS LOAD-DO NOT USE!
-02.0   92     6.57   1314     443   46894   5816     90.9    0.356  !DANGEROUS LOAD-DO NOT USE!
+00.0   94     6.70   1340     461   49798   5953     91.7    0.347  !DANGEROUS LOAD-DO NOT USE!

 

[oldguyguns]

Can see the difference in usable case capacity buy just wondering what was the actual length of each bullet? Also, I emailed Remington and also Hornady asking what the variation in length was for a specific FMJRN bullet. Remington replied that "they do not give out reloading recommendations". I responded that I did not want recommendations just variation in manufacturing of that bullet. Enough said for them--not more buying their products. Hornady replied that it was plus or minus .01 in. I measured 12 Rem 380 bullts and 12 Hornady 9MM bullets ( I know not statistically accurate) and found that Hornady was a lot tighter than their reply. The avg was .550 in and the spread between high and low was only .005 in. Good folks!!!

 

[trophyhunter]

The Hornady bullet measures 0.539"/13.69mm in length and the Sellier-Bellot is 0.598"/15.19mm so the difference between them is 0.059"/1.5mm. I used somewhat of an "All in Scenario" generating the QL tables selecting such a short COL and using a healthy charge of #AA5 but the end result is nearly 15,000 psi difference.

It's really important to avoid chambering a round over and over again to avoid bullet setback in the case, and stick to the manual recipes. Powder charge is just as important as adhering to the COL the testing lab publishes in a recipe for any given bullet.

I have records of production runs using Remington 115g FMJ-RN going back quite a few years and the average bullet length was 0.563"/14.30mm with no significant lot deviation shown back to 1996, maximum deviation was less than .003.

 

[oldguyguns]

Thanks for info. I learned a lot--appreciated--