What causes bad accuracy?

[HOV]

I've loaded some pretty good 9mm rounds but just started off with .45ACP. My first recipie was:

230 gr. Hornady XTP bullet
5.5 gr. Unique
CCI primer
PMC brass - once fired
1.230" COAL

Got that load from the Hornady reloading manual.

I took some rounds to the range with my trusty XD45, and the result was the worst accuracy I've ever had with any round ever. Just to rule out shooter or pistol error, I loaded up some Speer Lawman 230 gr. RN rounds and was back punching out bullseyes immediately.

One observation - my hand loads were quite a bit weaker than the Speer factory loads.

So what gives? What causes poor accuracy? Could it be not enough powder?

 

[LiveLife]

You may not have enough powder charge for consistent pressure build for your shorter barrel XD (most load data were tested on 5" barrels).

I usually load 10 rounds of powder charge in increments of 2/10 grain to identify the most accurate load.

Try 5.8, 6.0, 6.2 for your XTP bullets.

 

[rcmodel]

5.5 Unique is a very light load with a 230 bullet.
Probably getting less then 700 FPS, and you may have stability problems.

Bump it up to 6.5 grains for a standard velocity .45 ACP 230 grain load.

rc

 

[HOV]

Ok guys, will do. Appreciate the advice.

 

[Hk Dan]

What range are we talking about? In close, it shouldn't matter--I've seen rounds keyholed in the bullseye at 10 yards, and THAT is a stability problem...<g>

 

[HOV]

Close - 7 yards. I didn't see any keyholing.

 

[Steve C]

5.5grs of Unique should be adequate for a stabilized load.

If you are using a scale and adjustable powder measure to throw your charges then 5.5grs of Unique may just be too light for your pistol. If you are using a Lee dipper or powder measure with volume inserts and are relying on the charts to give you the charge weight you specified without checking the throw on a scale you are likely getting a lighter charge than you think. Lee's charts are optimistic and err on the side of safety by throwing lighter charges than listed in my experience.

6.0 grs of Unique will duplicate your typical factory load at around 850 fps from a 5" barrel. 6.5 grs is a pretty hot load and above the maximum 6.2grs shown in my Hornady data.

 

[Marlin 45 carbine]

inconsistent crimp could well be a factor but seems the O.P. has it in hand well enough to eliminate that cause.

 

[HOV]

Since I use a hand press and it's a slow process anyway, I just take the time to measure every load with a digital powder scale.

As far as crimp goes, I'm sure it's consistent but there's very little. Do you guys put some crimp on your .45ACP loads?

 

[Walkalong]

All you need on .45 ACP is a very light taper crimp. Just enough to remove the bell and a hair more.

 

[Myke_Hart]

You say you use a hand press.

The worst accuracy I have seen is from not seating bullets square or level in the case (crooked). This causes the bullet to hit the lands at a angle and causes the bullets to fly unstable.

Or a case that has been trimmed so that one side is higher than another.

I use XTPs quite often and don't usually have too many issues getting them to fly straight, and I wouldn't suspect a slow bullet (light load) to be a problem either.

I would check your finished rounds on a Concentricity Gauge just to be sure they are seating correctly. Harder to do with pistol rounds than long rifle rounds.

Just a few things to check before changing powder, bullets, primers, and what not.

 

[HOV]

Myke, that may be the best theory I've heard all day, and my intuition says you're right. But I don't understand how a hand press would be a factor in non-concentric bullet seating, as opposed to any other press.

I don't have a concentricity gauge but I do roll the rounds on a flat, black surface to see if I can detect any wobbly motion in the bullet. Not a technical measurement by any means... I suppose I'll invest in a concentricity gauge.

But before I make that investment, what are some techniques for getting the bullet seating die set up so the bullets have a better chance of seating straight? Or is it a flare issue, where I need to add more flare so I can put the bullets in by hand a little straighter before seating?

 

[Walkalong]

Starting them straighter really does help. I like the Lyman M die as copied by Redding. Really helps get the bullet straight, although you still have to set it in the brass pretty straight to start with. You can feel the difference seating a bullet started straight vs crooked.

 

[1SOW]

Walkalong said:

Starting them straighter really does help.

and I agree.

I use a turret press and try to sit very close to the same place every time I reload. I've had a lot of 9mm practice over the last year and can set the bullet in the bell close to dead on vertical. I use a minimum bell.

 

[HOV]

Gents, the problem turned out to be a crimp issue. I ran all the rounds from the trouble batch through my Lee Factory Crimp die and dialed in a little more crimp. They ran just fine after that - cycled well and shot straight.

Thanks for all the advice.