reloading for accuracy

[alexisjohnson]

Hey guys,

I've been creating test batches of different powders in 9mm (115 grain JHP's) and with my skill level i can't really tell any differences in accuracy for the different amounts of powder. My first question was at what distance (glock 19) do you start to notice accurate batches. Will you typically be resting the gun on something or shooting offhand?

Another thing i've been playing with is the OAL and how it alters the recoil, as well as potential accuracy.

I've noticed that the shorter the OAL (the deeper the bullet is set in) the harsher the recoil (and the higher the velocity i presume). How do you guys typically set your ideal OAL? Do you set it out long enough where it touch the rifling and then bring it down? As far as OAL and accuracy goes...is there any correlation. If there is...at what distances would i begin to see this correlation?

I'd appreciate any input or insight into these issues.

Thanks again!

[BigBronco]

If we are all about accuracy then a Ransom Rest is the bets for working up loads. Always use a rest for load development. If not using one you must be 100% confident in your shooting skills.

[67Cuda]

Ransom Rest is the bets for working up loads.

I see why they use Ransom in their name.

[rsrocket1]

If you can't test with a ransom rest and you are not already accurate to be able to see the difference "accuracy loads" for handguns shooting offhand are a waste of time. If you are shooting at 10 yards or less, unless the gun is bad, you should be able to put all your rounds inside a 3" sticky note.

Yes it would be nice to know that it's your own shooting that is causing the inaccuracy rather than the gun or load. That way you know that you can see your improvement as your shooting develops. But for right now you should pick a load that feeds and cycles your gun reliably and practice, practice, practice.

You'll notice accuracy differences at 25 yards again with a gun vise or ransom rest.

Just like with a rifle, muzzle velocity affects accuracy so anything that affects muzzle velocity such as powder charge weight and bullet seat depth will affect accuracy. Seating a bullet deeper decreases the volume in the case and raises pressures which will raise velocity. Be careful, the pressure increase is greater than the velocity increase. For instance, a 10% increase in seating depth may increase your muzzle velocity by 10% but it may increase the peak pressure by 20% and 9mm is already a small volume case.

Usually you set your seating depth (OAL) to ensure all your cartridges fit in your magazine. 1.169" is the SAAMI max but that's for round nose, JHP, FP, TC should all fit that same profile but be considerably shorter, typically 1.135". Choose your OAL for reliable feeding in your gun, then adjust the charge for the velocity or recoil that reliably cycles the gun and locks the slide back on the last shot 100% of the time. You can make a few dummy rounds to test the feeding, then make test rounds of different charge weights for shooting.

Remember, limp wristing will cause lighter recoiling loads to fail to cycle so some loads will work with one shooter and not another. In that case you are too low with your loads to work for everyone.

So in a nutshell
Set OAL to reliably work in your magazine and feed into your gun (dummy rounds)

Start with a published load (mid range or with Alliant Powder, 10% below their published load which is always maximum load).

Adjust the charge weight to where you feel comfortable with it while ensuring reliable cycling and lock back on last shot.

If you want more data on load development and plots of OAL vs MV and Pmax, I can send them to you but for now, I think you want to simply find a comfortable load and shoot a lot.

[ar15barrels]

I've been creating test batches of different powders in 9mm (115 grain JHP's) and with my skill level i can't really tell any differences in accuracy for the different amounts of powder.

You need a machine rest to eliminate the user error and be able to see differences in accuracy with most handguns.
If you can't tell a difference in loads how you actually shoot them, you are wasting your time with even trying to find a more accurate load.
Just load what runs the gun well and gives you the velocity you desire.

Seating deeper increases the pressure and therefore the velocity.

[Carcassonne]

Hey guys,

I've been creating test batches of different powders in 9mm (115 grain JHP's) and with my skill level i can't really tell any differences in accuracy for the different amounts of powder. My first question was at what distance (glock 19) do you start to notice accurate batches. Will you typically be resting the gun on something or shooting offhand?

Another thing i've been playing with is the OAL and how it alters the recoil, as well as potential accuracy.

I've noticed that the shorter the OAL (the deeper the bullet is set in) the harsher the recoil (and the higher the velocity i presume). How do you guys typically set your ideal OAL? Do you set it out long enough where it touch the rifling and then bring it down? As far as OAL and accuracy goes...is there any correlation. If there is...at what distances would i begin to see this correlation?

I'd appreciate any input or insight into these issues.

Thanks again!

Set your target at the distance you can best see it and align it with your sights. If the best distance for you is 5 yards then that is the distance you should test your ammo.

I set the bullet 0.025" short of touching the lands.

I shoot from a sand bag.


.

[Carcassonne]

...

Seating deeper increases the pressure and therefore the velocity.

I don't agree with that.

Increased pressure doesn't equal more velocity.

Seating the bullet longer gives more room for powder. Using more slower burning powder will give you increased velocity without going over pressure.


.

[SixPointEight]

Set your target at the distance you can best see it and align it with your sights. If the best distance for you is 5 yards then that is the distance you should test your ammo.

I set the bullet 0.025" short of touching the lands.

I shoot from a sand bag.


.

Don't load .025" off the lands.

Ain't nobody single-feeding their glock. Load to mag length OP. Forget precision pistil loads if you aren't trying to shoot bullseye. Load to a velocity, cleanliness and recoil goal instead

[SixPointEight]

I don't agree with that.

Increased pressure doesn't equal more velocity.

Seating the bullet longer gives more room for powder. Using more slower burning powder will give you increased velocity without going over pressure.


.

For a given mass of powder, and therefore volume of gas, decreasing the volume of the combustion chamber will increase pressure and velocity.

When you start changing things like powder charge, the relationship changes. So for a given charge, seating deeper will tend to increase velocity and pressure, seating longer will decrease velocity and pressure. It's not necessarily linear though, which is why when you seat longer you can get more use more powder to get more velocity at the same pressure. You effectively increased case volume.

See .30-06 and .308 for reference

[dmy]

Consistency is the key

OP:
I have found that incremental increases in the amount of powder does not have a huge effect on accuracy. In my experience, consistency is the key to getting groups to shrink. Consistency is achieved with cases with the same lot number (or at least the same head stamp), trimmed to the same length, deburred and chamfered as consistently as possible, charged as consistently as possible, seated and crimped as consistently as possible. That being said, you may find that your particular gun has a sweet spot where it performs better with a certain charge weight of a given powder.
Since most people do not have a Ransom Rest, you should use some type of rest such as sandbags, carpeted wood blocks or something to steady your gun when testing loads. Many people say not to rest the barrel on the blocks, but to rest the receiver on it.
I tend to disagree that, if you only shoot at 5 yds, then you don't need to worry about grouping loads at longer distances. While not scientific, if a gun is capable of shooting groups of 1" at 30' and someone is only capable of shooting off-hand groups of 3" at 30', then the combined theoretical grouping is 5" at 30" (your accuracy with a +/- of 1" on either side of your groups). I believe everyone agrees that an accurate handgun and load is desireable and I commend you for trying to achieve the most out of your equipment and skill.

[RestrictedColt]

Seating depth should be as the book prescribes for that bullet unless you know what you're doing and are after something specific. Seating shorter increases pressure, but not necessarily the velocity. There'll probably be a harder high pressure spike initially, what it does by the time the bullet exits you'll only know with a chronograph. Altho recoil would seem like a good indicator, I've had loads that felt hotter but run slower and vise versa. You can also run over safe pressures without an obvious recoil feel of it.

[ar15barrels]

Increased pressure doesn't equal more velocity.

Ok, sure, whatever.

[tanks]

... Seating shorter increases pressure, but not necessarily the velocity. ...

Interesting. Every time I have increased the OAL I had to increase the powder charge to match the velocity of the shorter round. Different physics must have been at work between your rounds and mine .

[Robert1234]

Haven't seen it mentioned yet here, get a chronograph if you're testing loads. It will tell you how consistent your loads are. Without it you're just guessing at velocities.

[SixPointEight]

Haven't seen it mentioned yet here, get a chronological if you're testing loads. It will tell you how consistent your loads are. Without it you're just guessing at velocities.

That might work, but I might try a chronograph myself