Newbie Ammo Q? Heavier bullet = Less powder?
This is a discussion on Newbie Ammo Q? Heavier bullet = Less powder? within the Defensive Ammunition & Ballistics forums, part of the Defensive Carry Discussions category; This is something I've been wondering about for a while. When dealing with traditional production ammo, does a heavier grain bullet leave less room for ...
Post By Ianthin
Post By bmcgilvray
May 9th, 2014 10:09 PM
Newbie Ammo Q? Heavier bullet = Less powder?
This is something I've been wondering about for a while. When dealing with traditional production ammo, does a heavier grain bullet leave less room for powder? Likewise does a lighter bullet carry a heavier charge? What motivated me to ask is I just bought my first .40, a SW40VE, and picked up a couple of boxes of WWB for the range tomorrow. One box of FMJ 165gr and another of 180gr JHP. Standing side by side they are the same overall length, and the JHP is noticeably more narrow at the tip than the flat nosed FMJ. That tells me the 180gr must seat deeper in the case than the lighter 160gr. So does one carry a lighter charge than the other?
I get that when reloading there is room to adjust these things to ones personal preference, but for factory loads is there a certain rule of thumb so to speak? I know they follow the SAAMI standards.
Thanks in advance for the knowledge.
May 9th, 2014 10:09 PM
May 9th, 2014 10:48 PM
The heavier bullets do take up more room in the case, reducing volume and so propellant powders must be adjusted to compensate. Propellant powders that are confined generate higher pressures than the same charge in a container having larger volume and so less confined. In addition to that, the heavier bullet has more inertia to overcome before it begins its journey down the barrel. More inertia raises pressures of the powder charge fueling the load hence the charge weight must compensate for this. Furthermore, heavier bullets frequently have more surface area bearing on the interior surfaces of the barrel; more surface area increasing friction which acts to raise pressure of the propellent charge which must be adjusted to compensate.
Powder charge reductions compensate. Powders having different, frequently slower burning rates also may be used to compensate. Handloaders move between different canister grade powders to adjust loads to meet needs while maintaining safe pressures. Canister grade powders are lots of powders that prove to perform to a uniform set of standards as to burning rate and so are labeled and sold to the trade. Much more propellant powder is manufactured than what is seen conveniently packaged and sold to handloaders at local gun shops. This non-canister grade powder is tested for burning characteristics and loaded by the factories, the loads being adjusted lot to lot to specified velocities and pressures.
It's a lot more complicated in some ways than is explained above and more complicated than my paltry knowledge of such. Factories mix and match and blend propellants in ways no handloader could ever safely attempt without laboratory testing to back him up. Factories produce quite good ammunition for the most part.
One other thing. "Does a heavier weight bullet leave less room for powder" is better than to say ""does a heavier grain bullet leave less room for powder." Practical correct usage would be to just say "heavier bullet." No such thing as heavier grains and lighter grains as a grain is 1/7000 of a pound. One wouldn't say: "that black bass is a heavier pound fish than that crappie."
“No possible rapidity of fire can atone for habitual carelessness of aim with the first shot.”
Theodore Roosevelt, The Wilderness Hunter, 1893
May 10th, 2014 08:46 PM
bmcgilvray explained it quite well. Yes, a heavy bullet will be seated deeper into the case than a lighter one. They both must be seated to the specifications given for a specific cartridge and will therefore have the same overall length . As bmc stated, a faster burning powder can be use with the lighter while the heavier one will likely be loaded with a slower burning powder. We have little to no idea what powders the manufacturers use. Their formulas are usually proprietary and they aren't about to tell us. They specify to the powder makers what they want and usually only they can get it. Internal and external ballistics are sciences and are extremely interesting. Just type one into a search engine and you will find hundreds of thousand pages to read.
May 10th, 2014 09:37 PM
In addition to the above confusion &/or clarity, I have learned different 'Brands' of ammo, in the same caliber & bullet weight, can have variances in overall cartridge length.
These very minor differences may perform differently in your sidearm(s).
It is good to find specific weights & brands that perform best in your specific firearm Model.
Then, my seeming identical SW40VE may vary just enough from yours to have slightly different ammo preferences.
I find WWB works well enough for 'range-grade' ammo in all my .45acps with the occasional FTE being good practice for clearing a malfunction.
Also, I have found Speer GDHP +P 200 gr to work flawlessly in all of them, which allows me to buy in bulk for practice or carry.
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Here are some Duty Rounds the FBI lab has certified for adequate penetration & expansion.
Barnes XPB 115gr HP (35515) such as loaded by Cor-Bon (DPX09115)
Winchester Partition Gold 124gr JHP (RA91P)
Winchester PDX1 124 gr +P JHP (S9MMPDB)
Winchester PDX1 147 gr JHP (S9MMPDB1)
Winchester Ranger-T 124 gr +P JHP (RA9124TP)
Winchester Ranger Bonded 124 gr +P JHP (RA9BA)
Winchester Ranger-T 127gr JHP +P+ (RA9TA)
Winchester Ranger-T 147gr JHP (RA9T)
Winchester Bonded 147gr JHP (RA9B/Q4364)
Speer Gold Dor 124gr JHP
Speer Gold Dot 124gr JHP +P (53617)
Speer Gold Dot 147gr JHP (53619)
Remington Golden Saber 124 gr +P JHP bonded (GSB9MMD)
Remington Golden Saber 147gr JHP (GS9MMC)
Federal Tactical 124gr JHP (LE9T1)
Federal Tactical 135gr JHP +P (LE9T5)
Federal HST 147gr JHP (P9HST2)
Federal HST 124gr JHP +P (P9HST3)
Barnes all-copper bullets (140 & 155gr) loaded by: Cor-Bon (DPX40140)
Winchester Partition Gold 165gr JHP (RA401P)
Winchester PDX1 165 gr JHP (S40SWPDB)
Winchester PDX1 160 gr JHP (S40SWPDB1)
Winchester Ranger 165gr JHP (RA40TA)
Winchester Ranger 180gr JHP (RA40T)
Winchester Bonded 180gr JHP (Q4355)
Speer Gold Dot 155gr JHP (53961)
Speer Gold Dot 180gr JHP (53962)
Federal Tactical 165gr JHP (LE40T3)
Federal Tactical 180gr JHP (LE40T1)
Federal HST 180gr JHP (P40HST1)
Remington Golden Saber 180 gr JHP (GS40SWB)
Barnes XPB/TAC-XP 185gr HP loaded by:
Winchester PDX1 230 gr JHP (S45SWPDb)
Winchester Ranger-T 230gr JHP (RA45T)
Winchester Ranger-T 230gr JHP +P (RA45TP)
Federal Tactical 230gr JHP (LE45T1)
Federal HST 230gr +P JHP (P45HST1)
Federal HST 230gr JHP (P45HST2)
Speer Gold Dot 230gr JHP (23966)
Speer Gold Dot 230gr +P JHP (53969)
Retired State Trooper (40 long years) 8 years State Range Instructor - BS Degree- Justice, MS Degree- Criminology
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