Effect of OAL on 9mm 9mm loading frustration

[au_prospector]

Guys I have a question regarding 9mm OAL and accuracy effects.

When I measure factory loads on 124gr RN I am getting OAL lengths of 1.15 or even a little longer. Federal American Eagle is 1.153 and Winchester NATO is 1.156.

I just loaded up a batch of Xtreme 124 RN and seated them to 1.15 and some are as long as 1.153. They "plunk" fine. I have tried 3 different powders and am not getting even "factory accuracy". I have used Unique, CSB-1, and 800-X. I fixed an overcrimping issue and now barely crimp at all with no deformation to the bullet. Still, accuracy is suffering.

My question is I am using powder data which states to seat them in the 1.11 to 1.13 inch range. Dont I want the bullet closer to the lands? Also I am using the same amount of powder the recipes call for with shorter OAL, should I bump it up a bit?

IMR load data says 1.125
Lyman does not list a 124 gr FMJ, but most all the 9 mm data is even shorter.
Alliant states 1.12

 

[egd]

I'll give this a shot (pun intended). Think of it this way. When a completed bullet fires it is a controlled explosion. The amount or power of that explosion depends on the type and amount of powder used and the confined space it builds up pressure in to explode. If you make that space bigger, by lengthening the oal, you reduce the power of the explosion.
Therefore if data says 1.1 and you use 1.5 length you aren't getting as much power and may be too low. Every gun shoots a little different and likes different loads and lengths. Closeness to the lands is, IMO, something that really is only important to rifle shooters, and even then more so to long range types. For a pistol, function in the mags and the gun feeding mechanism would determine oal, then adjust powder load accordingly within loading data in the manuals. But any given pistol can shoot several oal lengths. It's something you just have to play with a little. There is no exact right answer.

 

[papaairbear]

Here is a thread on advanced reloading that answers your question clearly, http://www.thehighroad.org/showthread.php?t=778197

It's a very informative read for beginners and old hats as well.

 

[JamieC]

Relax, the difference between 1.153" and 1.156" is 3 thousandths of an inch, roughly the thickness of a human hair! One of my guns limits most of my 9mm loads to no more than 1.100". I just backed off my average starting point, (from more than one manual), about 10%, worked up till I found what worked safely and accurately. You'll find your OAL will move around a couple of thousandths, don't sweat it.

 

[Rule3]

Forget the "factory" ammo as you are not using the same bullet.

Clear your mind of that

Extreme are plated bullets correct? I don't use them (so I do not know) but your load data should be middle of the road FMJ data to start with,(or lead data) but I prefer the middle FMJ.

As to seating, use the plunk as you have been no need to fuss with that once it plunks fine

Now it's what powder and how much???

Stay with one powder (say Unique) and control that one variable.

 

[rodregier]

with plated try to go easy on the crimp as long as you get them to "plunk".

Squishing them with the crimp is not conducive to accuracy.

 

[243winxb]

NRA PRECISION PISTOL shooters on http://www.bullseyeforum.net claim plated bullets finish last for accuracy. They should know by testing with Ransom rests and fixed test chamber barrels. Shooting offhand, only a high master could tell the difference in accuracy, not i. http://s338.photobucket.com/user/joe1944usa/library/Plated VS Jacketed Bullets

 

[LiveLife]

Effect of OAL on 9mm loading frustration ... and accuracy effects.

Xtreme 124 RN and seated them to 1.15 and some are as long as 1.153.

... Unique, CSB-1, and 800-X. I fixed an overcrimping issue and now barely crimp at all with no deformation to the bullet.

Still, accuracy is suffering.

My question is I am using powder data which states to seat them in the 1.11 to 1.13 inch range. Dont I want the bullet closer to the lands? Also I am using the same amount of powder the recipes call for with shorter OAL, should I bump it up a bit?

Accuracy results from consistent muzzle velocities which results from consistent chamber pressures. To increase accuracy, you must adjust reloading variables to achieve more consistent chamber pressures.

In theory, while using longer OAL will decrease gas leakage and "supposed" to increase chamber pressure consistency, but if you are using slower burning powders at lower charges (especially with load data that used shorter OAL), you may not produce efficient enough powder burn to create consistent enough chamber pressures to produce accuracy.

My experience with Unique has been that it needed to be loaded near the top to achieve optimal accuracy. If you don't want to increase powder charge, you can try reducing OAL down to 1.130"-1.135" to increase neck tension and see if accuracy improves (but I would determine max case fill at shorter OAL first to ensure I was not compressing the powder charge). As to taper crimp, for .355" diameter plated bullet, I would use no more than .377" to not cut into the plating (.355"+.011"+.011" = .377").

FWIW, I have had better accuracy with faster burning powders and BE-86 over Unique at mid-to-high range load data with plated bullets - http://www.thehighroad.org/showthread.php?p=9924922#post9924922

Regular thickness Berry's plated bullet at 25 yards

Thick plated RMR HM bullet at 25 yards

 

[Rule3]

NRA PRECISION PISTOL shooters on http://www.bullseyeforum.net claim plated bullets finish last for accuracy. They should know by testing with Ransom rests and fixed test chamber barrels. Shooting offhand, only a high master could tell the difference in accuracy, not i. http://s338.photobucket.com/user/joe1944usa/library/Plated VS Jacketed Bullets

I am no where near a precision shooter but do shoot a lot of 9mm in different guns and am fairly good.

I do not think much of plated bullets either. I had several boxes of (name withheld)
that I could divide up into 4 separate groups by length, weight. They just were not constant in how they were made.

 

[alexcue]

Just throwing my experience with Xtreme's 124gr RN. I load them to 1.142" C.O.L. Why did I pick this number? cause that's what Freedom Munitions (their sister company) loads their new ammo.

It's worked in 4 of my 9mm's with no problem. Just like the factory ammo does.

 

[egd]

Rule3, and anyone else for that matter, what do you consider as acceptable tolerance for weight and length of a batch of bullets? I have wondered about that in the past.

 

[TimSr]

Looking just at accuracy, the seating depth is low on the list of priorities to dial in a load. It's also difficult to dial in a load with multiple variables at play.
Bullet choice is probably first, powder choice 2nd, powder charge 3rd. Things like sating depth and primers are for fine tuning after you've got a combo that shows promise.

Stick with one bullet, one seating depth, and one powder, start at minimum and work up within the published range, until you find what works best. If it's not acceptable, try again with a different powder.

Personally I like to start loading any caliber with actual published components (jacketed name brand bullets) to establish a quality baseline, before substituting budget bullets. Then you aren't left wondering what the obstacle is.

 

[Rule3]

Rule3, and anyone else for that matter, what do you consider as acceptable tolerance for weight and length of a batch of bullets? I have wondered about that in the past.

I can not really answer that in terms of a variance or percentage. Pretty much you want them to be as close as possible

Weigh some "real" bullets like Hornady, Sierra, Nosler whatever and see how close they are compared to xyz plated. Even good lead bullets will vary a bit just the nature of making them.

But we are OCD and anal.

I don't think your issue is the bullet. More of powder variable. Stick with one powder, (within the load data) do not over crimp and check your plunk testing with the bullet you are using. Some guns like some bullets and loads vs others. Just so many variables.

I blame the Sun in my eyes!

 

[LiveLife]

what do you consider as acceptable tolerance for weight and length of a batch of bullets?

My bullseye match shooting mentor wanted bullet weight variance less than 1 grain and would have me shave the lead from FMJ base.

Montana Gold jacketed bullets were my match bullet of choice for USPSA and weight variance are within 1 grain. I have been replacing them with jacketed bullets from RMR and weight variance are within 1 grain on average.

I have found plated bullets to vary by 1-3 grains on average and lead bullets up to 5-7 grains depending on the manufacturer.

 

[greyling22]

have you tried slugging the bore yet? My 9 wanted a .358 sized bullet.

 

[luzyfuerza]

Just to see how OAL affects velocity for a load that I like, I put together a bunch of 9mm rounds using range brass, powder from an old canister of Bullseye, CCI 500s, and Extreme 115gr CPRN bullets. I held most variables, including powder charge, constant. I varied OAL and measured velocities with the following results:

OAL=1.130" vel=1138 fps SD=15

OAL=1.120" vel=1128 fps SD=10

OAL=1.110" vel=1136 fps SD=19

OAL=1.100" vel=1131 fps SD=8

For me, for the gun I use, for this powder/brass/bullet/combination, within the range of OAL I tested there didn't seem to be much difference in velocity. Test your own combinations, of course, but within reason for well-behaved powders it looks like OAL is probably a secondary variable.