Factory Load Powder-Charge Variance

[edSky]

Ok, in my quest to improve my knowledge and skills (and save money) I decided to pull a flat of factory cartridges and see why they didn't perform so well. The cartridges are Remington UMC 115 gr FMJ 9mm in the 250 count mega-box.

Anecdotally the UMC feels like it has less recoil than Winchester USA 115 gr FMJ. I have also had some problems cycling with the UMC in a short barreled 1911. And when I use it in a less finicky pistol they seem to be all over the target like buckshot.

I just used my press and a bullet-pulling die to take apart 50 cartridges and weigh a sampling of their charges. Since I have a beam scale, and my initial goal was to scavenge the primed cases and bullets, I didn't weigh every single charge. What I found was a range of powder charges between 3.8 and 4.1 grains. The mode was close to 4.0 grains. This equates to a relative error (comparing the lightest load to the heaviest load) of approximately 7.5%. To me, 7.5% is a large relative error. Between that and the apparently light charge I thing it explains the scatter pattern of my shots.

Has anyone else taken the time to examine factory loads to check their powder charge variance? Thanks.

 

[ny32182]

I tore down 40 rounds of super crappy Pakistani .308 once, and found a charges varied evenly over a max spread of around 1.3 grains (approximately a 45gr charge), and bullet weights varied by a max spread of 2.7 grains (supposed to weigh 147 grains if I believe).

I loaded the exact average charge back into each case, seated the bullets to a more uniform average OAL, and fired them... the performance was improved somewhat.

 

[Chief-7700]

As far as pulling factory ammo and measuring the powder has no real value.
Reason they do not use the same powder that is available to the reloader so the blend of powder charge can very with the same results.
Chief

 

[NCsmitty]

I did that to 40 rounds of 7.62x54R Albanian ammo last summer. IIRC, the powder difference ranged about 1.4gr with the average at 49.5gr.
The 7.62x54R.net site says the average should be 48.7.
The bullets were amazingly close, averaging 149.3 with about .5gr difference. They were 149gr boat tail and actually was a nice looking steel core bullet.
While reassembling, I dropped 4gr from the average and reloaded them @45.5gr. and used my lee crimper. The original loads kicked like a mule in my M44 Mosins. I haven't shot the new loads yet.

NCsmitty

 

[edSky]

As far as pulling factory ammo and measuring the powder has no real value.
Reason they do not use the same powder that is available to the reloader so the blend of powder charge can very with the same results.
Chief

Chief, I'm not trying to reload using Remington's powder. I was trying to find out why their rounds are so inconsistent. I will get a chronograph soon and will get more empirical measurements, to compare the velocity with, say, a Winchester. But what really bugs me is that their loads are off so much from cartridge to cartridge. To me, a spread of 0.3 grains when we're talking a 4.0 grain load is a lot.

 

[JimKirk]

What would happen if you say ...used the same bullets, same primed cases and metered the same powder to a more even number. Get the results. Then do the same except with some of your own powder(to a comparible Velocity level). Get the results. There has to be something that is causing the variations you're getting. Kinda like going to the doctor....take this pill...come back in two weeks....repeat ...repeat....either you out live the cause, get the right pill or you die!
JimmyK

 

[Shoney]

edSky
What type of powder was it? Flake or spherical (ball)?

 

[glockster157]

Also check the crimp. If you decide to reload this brass with the same bullets, I would run the mouths of the cases back thru a sizer die and crimp well. I have recently tested some 38spl and 40 sw loads over my chrono and I found that the ones with stronger crimps were more uniform in velocity in my auto and revolver ammo. I have been reloading for years and I am ashamed to admit that I have not done that much crimp variation testing even though I have read several articles extolling good crimps. I should have as it does make a big difference, at least from what I have seen so far.

 

[edSky]

The powder is a very silvery looking flake.

My plan is to set aside the powder and reload using Unique or Titegroup, and of course put a quality taper crimp on them. The cost of new primed Remington brass and bullets is close to (if not more than, with tax and shipping) the cost of the box of 250. And when reloaded properly I'll have a far superior product. I am pretty good about weighing charges - I'll check every three or four and any that look "suspicious" - and have no problem dumping and reloading

A chronograph is definitely in order, and I've got one on my wish list. I am just too darned cheap, in debt, and balancing buying consumables with luxury items. The chronograph will make it easier to see what's going on with those factory Remington UMCs.

I'm not sure I'm going to work up charges with their powder, though, since a little powder goes a long way and it's one of the cheaper components. And besides, we all know that 10 dollars worth of components can be turned into the equivalent of 20 dollar cartridges.

 

[Galil5.56]

I will get a chronograph soon and will get more empirical measurements

I think you will find them "slow" when you get a chronograph compared to WWB, if the numbers match what I have read from others. Even if they make factory spec (1135 fps) that is pretty tame for 115 FMJ. Not only kinda slow, but Rem seats the bullet a lot shorter than WWB; which is around 1.165" or so in my experience... Maybe some really bad batches from Rem have gotten out and those make the press, but I have read of what seems more than coincidence of higher rates of failure to feed, sluggish slide speed, weak ejection, you name it with Rem UMC.

 

[Steve C]

Factory ammo isn't loaded like you and I do handloads. They manufacture in mass using bulk powders that charge weights are determined by a ballistic lab in the factory to produce a specified pressure for the particular batch of powder. They may run different batches of powder on different loading machines so their may be a variation in charges thrown but the pressure and velocity will be within what the factory specifies for that load.

Bullets are fed into the packaging from mixed loading machine sources. So a variation in charge weight wouldn't be unusual or an indication of poor loading practice.

The FBI have helped convict many persons using fallaciously based forensic analysis of bullets collected in crimes where they claimed that the lead analysis of one bullet can then be matched to a particular box of bullets, most often owned by a suspect. After many years of this "assumption" one of their analysts contacted the ammo manufactures as to their processes and showed that because of the mixing of loaded rounds from many different production machine and sources that one couldn't say that a particular round belonged to any particular box or batch of ammo.

 

[45ACPUSER]

Seems like a lot of work for a whole lot of nthing!