Reloading

[Danger Mouse]

can any minute changes in reloading change the accuracy, even if using the same primers, powder, and bullets?
Example:
First reloads .45 ACP
Winchester primers
Win 231 powder Lee book calls for 4.8 min 5.5 max - reloaded with 5.2
200 grain cowboy action LRN bullets
OAL Lee book states not less than 1.90, I set OAL at 1.95
Accuracy @ 21 feet with G30 was about 3 inch group

New reloads: .45 ACP
Winchester primers
Win 231 powder Lee book calls for 4.8 min 5.5 max - reloaded with 5.0
200 grain cowboy action LRN bullets
OAL Lee book states not less than 1.90, I set OAL at 1.90
Accuracy @ 21 feet with G30 Terrible! about 10 inch!

Notice the only thing changed was the OAL dropped by .05" and used .2 grams less powder. Is this change enough to effect the accuracy that much?

[DefensiveCarry.com]

[bmcgilvray]

Not really. I can flinch more than that. I can't imagine that such small changes would translate to such large accuracy variations at 21 feet. I'd be looking for some other sort of mechanical reason for such a fluctuation.

You mention lead bullets. Could barrel leading have taken it's toll between the testing of the first batch and the second?

Ambient temperature differences can affect velocities of a given load more than the incremental differences in loads that you illustrate. Seating depth can make a distinct difference but not nearly that much. My ancient Colt Model 1901 in .38 Long Colt has a .363 bore diameter and throws more accurate keyholes at that distance with .358 diamenter semi-wadcutters than the results you're obtaining from that second load.

[Ram Rod]

I don't reload for pistol calibers (yet). You are talking about 5/100ths of an inch here. Me-and my rifle calibers, I'm worrying about thousandths of an inch. .003 to .006 can mean alot in rifle loads especially if you're already within 3/1000ths of touching the lands. Did you see any signs of higher pressures with the 1.95"? Chamber one to see if the rifling engraves the bullet? Again--just a rifle reloader here, to me 5/100ths is an OAL change I'll never see.

[rocky]

I thought Glocks were not suppose to use lead bullets due to polygonal rifling and lead build up?

[Ram Rod]

I thought Glocks were not suppose to use lead bullets due to polygonal rifling and lead build up?

Yeah---that too!

[Tubby45]

You can shoot lead in Glocks but it usually has to be hard alloy and you need to clean it out every 100-200rds.

HKs also have poly rifling.

Accuracy can go one way or the other and can be pretty dramatic. Sometimes a tenth of a grain is all it takes. Shoot more at that second load and see what happens. Might be a fluke.

[Sharp]

He may have dropped an after market barrel in the G30. If not, then as bmcgilvray said maybe the lead fouling was to blame. Were both of these loads shot on the same day?(everybody has their off days) How consistently uniformed is the lead?

[friesepferd]

HKs also have poly rifling.

woh, i didnt know that. is it better to just not use lead then?
or at least clean it a lot?

[rocky]

It is tough getting fouling out sometimes. Guess it depends on how much cleaning you are willing to do. I use plated bullets. They are cheap, but seem to leave less lead fouling , compared to lead bullets.

[HotGuns]

OAL Lee book states not less than 1.90, I set OAL at 1.95

That is a .050 difference, or 50 thousanths. That is a lot of difference.

Also, you are using bullets meant for a .45 Colt, which is different than a .45 ACP. The .45 Colt bullets are meant for a revolver, not a semi auto.

You nose profile is round, but your bearing area is minimal, meaning that you have a small bearing surface on your bullet to contact the barrel. This makes for an unstable bullet, which although it works OK for the .45 Colt, makes it leass than desirable for the ACP.

Also, one of the reasons NOT to shoot lead in the standard polygonal rifling is that the base of the bullets dont quite obturate and seal the bore when being shot....this causes exessive leading which results in poor accuracy.

Any semi auto ought to be able to do 2 inches from the bench at 25 yards.

First thing I would do is try a jacketed bullet, one meant for the ACP, and not the Colt.

[Ram Rod]

That is a .050 difference, or 50 thousanths. That is a lot of difference.

Well, that's what I was getting at although I only reload for rifle currently.

I don't reload for pistol calibers (yet). You are talking about 5/100ths of an inch here. Me-and my rifle calibers, I'm worrying about thousandths of an inch. .003 to .006 can mean alot in rifle loads especially if you're already within 3/1000ths of touching the lands. Did you see any signs of higher pressures with the 1.95"? Chamber one to see if the rifling engraves the bullet? Again--just a rifle reloader here, to me 5/100ths is an OAL change I'll never see.

Do yourself a favor and quit whatever you're doing and research this fully---before you have a bad KB! Seriously.

[Tubby45]

woh, i didnt know that. is it better to just not use lead then?
or at least clean it a lot?

Heckler & Koch - Group Website

Two-thirds the way down:

...
polygonal bore profile for increased velocity, easier cleaning, and longer barrel life
...

You can use lead in barrels with poly rifling but you have to clean the barrel very often. For that reason, I switched to a KKM stainless steel "normal" rifling barrel.

The correct term for the rifling profile is hexagonal vs octagonal. I just call it poly cause it's easier. These are the Glock profiles. All 45 caliber guns have the profile on the right, all other calibers look like the left.

Why do the .45 caliber Glocks have octagonal rifling vs the hexagonal rifling in the other calibers?
The octagonal rifling provides a better gas seal in the large caliber .45 ACP. Notice how the image on the right has a lot less space between the bullet & barrel compared to the image on the left:

The Glock FAQ [Barrel Information]

Here is a good read on lead in Glocks. The OP is a new member I brought over here from Glocktalk. I think he is cz93x62 over here. He uses a similar name elsewhere, over on GT and on the Castboolits site. Freisepferd, when you start bullet casting, head on over there. Quite a few of us in the UP.

Glock Demystification--Step 1 - Cast Boolits