.45 ACP Load Anomoly

[federali]

Online reloading sites, my manuals and forum postings show that five grains of Bullseye behind a 230 grain FMJ bullet pretty much duplicates the military ball load, with some sources showing up to 900 FPS for this load.

I loaded five grains of Bullseye behind a 230 grain plated bullet. The load was mild, easy to shoot and ejection was positive. But, I had a sudden opportunity to fire one through a chronograph someone had at the range and the aforementioned load showed only 739 FPS. in a 5" barreled S&W Mod. 1911.

Plated vs jacketed bullets: opinions are all over the place on this issue, some say used jacketed bullet data with plated bullets while the bullet makers themselves recommend data for lead bullets.

Does anyone feel that substituting a plated for a FMJ bullet is responsible for the lower velocity? I realize that one round through a chrono doesn't mean much but its owner was a stranger and I didn't want to intrude on his time.
I'd like my 230 grain ball loads to at least break 800 FPS.

[243winxb]

Does anyone feel that substituting a plated for a FMJ bullet is responsible for the lower velocity?

Yes is my guess. The plated would produce lower pressure, resulting in lower velocity. Bearing surface of the bullet also comes into play, along with seating depth. Like i said, just a guess.

[Unclenick]

Agree it could cause the problem by having less friction with the bullet and letting the primer push the bullet into the throat before the powder start pressure got up where it needs to be. Typical results for the load should be around 830 fps from a tight chamber. That works out to about 350 ft-lbs of muzzle energy which is typical of WWI era .45 ACP hardball and is still typical of commercial hardball today. Current military hardball has, IIRC, a 234 grain bullet loaded to about 400 ft-lbs, so more like 875 fps.

[Slamfire]

That seems awfully low. I get just at 800 fps with 4.5 grains Bullseye with a LRN with three different lots of Bullseye. I have, but have not chronographed plated bullets at this time.

The low velocity could be due to off axis errors in shooting over the chronograph. I plumb my Chrony and shoot a reference load precisely because of off axis errors with the thing.

Kimber Custom Classic



230 gr LRN Valiant 4.5 grs Bullseye lot BE532 (80's mfgr)  Mixed Brass WLP (brass)  OAL 1.250"	taper crimp .469"

16-May-09	 high 83  °F
		
Ave Vel =	782.7				
Std Dev =	13.41				
ES =	52.05				
High = 	815.5				
Low =	763.4				
N =	28				
					
230 gr LRN Valiant 4.5 grs Bullseye 99' & 2005 mixed lot Mixed Brass WLP (brass) OAL 1.250"	taper crimp .469"

16-May-09	 high 83  °F



Ave Vel =	805.2				
Std Dev =	38.07				
ES =	136.9				
High = 	912.4				
Low =	775.5				
N =	24				
					
230 gr LRN Valiant 4.5 grs Bullseye lot 827 (60's/70's powder) Mixed Brass WLP (brass)  OAL 1.250"	taper crimp .469"

16-May-09	 high 83  °F
					
Ave Vel =	822.9				
Std Dev =	14.14				
ES =	55.24				
High = 	853.7				
Low =	798.4				
N =	26