View Single Post
Old October 1, 2013, 12:48 PM   #11
Unclenick
Staff
 
Join Date: March 4, 2005
Location: Ohio
Posts: 10,226
Yes. It's tough to mold plastic into perfect geometry. Also, re flashing, I had some folded in from the edge of the drum on one of the two Lee PPM's I own. It may have been a fluke or an inspection failure. The other was fine. Just inspect for it.

The only measure I have that is more consistent with stick powder than the LPPM is the JDS Quick Measure. But it is less convenient to adjust and you can buy five LPPM's for the same money, so your choice is purpose-specific.


BoogieMan,

±0.2 isn't bad at all. You are correct that it's a smaller percentage of a rifle load than of a pistol load, but there are a couple of other factors to consider. One is that precision expectations from a handgun are less demanding than with a rifle. Short of benchrest or varmint class, if a rifle shoots under 1 moa at 100 yards, we tend to think it's pretty good, and at half an moa that it's doing exceptionally well. For a pistol the numbers are about 4 times higher at on fourth the range. A pistol that shoots 4 moa at 25 yards (about 1") seems to be pretty darn good, and 2 moa at 25 yards (about ½") seems exceptional. So, you get about sixteen times the load precision slack at the outset (sixteen times and not four times has to do with how group error sources add statistically, but I'm not going to go into that here). That is, a good rifle load can vary ±½% in charge weight without opening groups up substantially, and a handgun can usually handle more like ±8% load variation without seeing too much effect on 25 yard paper.

Don't take my word for this, BTW. Use a scale to load some 9 mm or .45 Auto rounds 8% low and some 8% high (not to exceed safe limits) and twice as many right inbetween. Shoot the inbetween loads into one group and shoot the others alternating high and low rounds and see if the results aren't still pretty close in POI. The main exception that comes to mind is when you get down too close to being unable to function the firearm properly.

Second, pistol barrels are short and rigid compared to rifle barrels. You usually find some minimum and maximum charge for best accuracy, but its often a fairly generous band that doesn't have a sharp tuning point like a rifle. This, again, has to do with statistical influence in the more generous precision expectation for pistol shooting and also lack of bending deflection.

Third, the ranges at which we use pistols are usually too short for difference in bullet drop due to shot-to-shot differences in velocity to greatly change point of impact. Instead, what affects point of impact most is the angle of elevation of the muzzle (firing angle) at the moment the bullet clears it. Well, for a given bullet, if you reduce pressure, the gun muzzle elevates more slowly, but at the same time the bullet takes longer to get out of the barrel, giving the muzzle more time to reach toward the same elevation angle at bullet exit. This tends to compensate for small load errors. It's not exact, but its close enough that I find point of impact at 25 yards is changed more by changing bullet weight than by adjusting charge weight, with heavier bullets impacting higher (because it takes a given pressure more time to move heavier bullets out of the barrel, resulting in higher muzzle elevation at time of bullet exit). In a rifle, though, due to barrel whip, going to a heavier bullet can result in either higher or lower POI.

Anyway, the bottom line is the pistol loads are a lot less sensitive to a given percent charge weight error than a rifle is. If you doubt what your powder measure can do, again, load some up by weighing individual charges and compare how they do with how your rounds loaded from the measure do. The nice thing about shooting is the target tells you when something matters and when it doesn't. No guesswork required.
__________________
Gunsite Orange Hat Family Member
CMP Certified GSM Master Instructor
NRA Certified Rifle Instructor
NRA Benefactor Member
Unclenick is offline  
 
Page generated in 0.04453 seconds with 7 queries