9mm accuracy problems

[Whiterabbit]

I never worry about things like that. Because that's testable.

Grab a bullet, grab some brass, and bell and seat your bullet to make a dummy. Measure OAL, then chamber it. Extract and measure OAL.

Do that a few times and see if the OAL changes much.

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Do that for a few crimps, up to and including barely enough crimp to remove the bell.

Then you don't have to worry, you have data.

And that data will establish what your crimp limitations are that you can play with while trying to shrink group size by half (which is your goal here)

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to reiterate, in my limited experience, short range pistol accuracy seems to be dominated by ignition reliability. Slow powders (maybe your universal, I don;t know) are more likely to be sensitive to case fill, where seating deeper gets you better case fill, while simultaneoulsy increasing tension on the bullet, which will also increase reliability. I suspect your 700x won't be sensitive to that. The dead giveaway there is if you are getting unburned powder in the barrel. That's a strong sign that burn variability is high. Doesn;t affect some people's downrange performance, but if that's you, time to change something.

This is assuming you don't have something absolutely fundamentally wrong, such as damaged bullet bases, or a powder/bullet combo that causes tumbling. If you have some that miss the paper at 30 yards, I do wonder about that. Are you able to tell if any bullets are tumbling? If so, your first step is to change powders (again). If that doesn't work, you change bullet weight or shape. If no tumbling, I'd try to make my bullet choice work.

[Bill Steele]

I too am not a big fan of the LFCD, but it is much less a problem with 9mm than some of the straight wall calibers (because 9mm is a tapered round, so the sizing ring generally won't touch anything up by the case mouth). The LFCD can be atrocious when loading lead or lead diameter plated in a st right walled caliber like 40SW or 45 Auto.

While your crimp dimension doesn't sound too bad, it may be if you happen to be loading with thicker cases and lead dimension plated bullets.

Forget the notion of the crimp holding the bullet, it doesn't in 9mm. You only want to straighten the case mouth out (take the belling out) and no more. It is the interference fit between the sized case and the bullet that holds the bullet, not the crimp. If a bullet can be pressed back into the case after loading, either your sizing die is too large, your brass too thin for the bullet diameter you are loading.

[Whiterabbit]

I agree. Might not be sizing die either, but an expander that is too large in diameter.

Also, for the desired load it might be worth polishing the expander anyways to create more case tension, if it's shown that ignition is not as reliable as it might be.

[Seaweed02]

OK

OK then fellas, I'll give those tips a try and report back in a few days. Thank you for taking the time to help me out.

[sixoclockhold]

Make sure the barrel is clean

Good rifling.

[Bill Steele]

OK then fellas, I'll give those tips a try and report back in a few days. Thank you for taking the time to help me out.

Oh, and when you get serious, buy these: https://www.precisiondelta.com/produ...m-124-jhp.html

Only bullets I load in 9mm, excellent bullet.

[Whiterabbit]

24 per 100. Jeez. I don't doubt they are a great bullet but surely for 25 yard shooting a perfectly great bullet can be found for much less.

[actionwatcher]

First, if you don't want to switch bullets and go away from plated, you can play with your seating depth. Also be sure that you're not crimping into those plated bullets because accuracy will go to hell quickly. Are you using any sort of post sizing die like a Lee Factory Crimp Die? If so, throw it in the trash.

I would suggest to try opposite. Try FMJ bullets (I can give you a dozen if you in South Bay). From my experience bullets are the biggest accuracy contributor. It is partially ogive on plated bullets that create variable effective sitting depth and partially weight/size variations. If you find that FMJ fixes you problem you found it. If not I would go with checking variations in powder charges if it is above 0.2 gr I would start care. For the pistol rounds, crimping, FCD and OAL are very secondary factors unless you are seriously overcrimping or OALing it beyond any reason. Actually I prefer FCD it seems reduce seating depth variations (no clinical studies though and might be pure placibo effect).

I also suggest to have at least light crimp. Because if there is no crimp a dirty feed ramp may create enough resistance to push the bullet in ( I saw such cases). As a result you may accidentally to get an high pressure round. Depending on your load it might be dangerous.

And to your other question - cast bullets are usually more accurate. Though for larger calibers the effect seems more pronounce. For 9mm I personally don't feel much of the difference between decent FMJs and commercial casts.

[___M|9||___]

whats your barrels twist rate, do you even know that?

[Whiterabbit]

If you find that FMJ fixes you problem you found it.

I would suggest that switching to an FMJ yielding positive results means nothing. More than one root cause for bad accuracy might show better results with an FMJ (or even Barnes) bullet. Such as changing bullet weight, changing bullet dimension, and changing bullet base quality. Just three examples that could make all the difference, and the old bullet might be cast, plated, or jacketed.

[Bill Steele]

24 per 100. Jeez. I don't doubt they are a great bullet but surely for 25 yard shooting a perfectly great bullet can be found for much less.

True enough if you are buying 100 at a time. I buy them by 1000, they are a little more resonable in those volumes (I.e. Less than half the 100 count cost.). Right there with XTP consistency.

[CalTeacher]

I would suggest to try opposite. Try FMJ bullets (I can give you a dozen if you in South Bay). From my experience bullets are the biggest accuracy contributor. It is partially ogive on plated bullets that create variable effective sitting depth and partially weight/size variations. If you find that FMJ fixes you problem you found it. If not I would go with checking variations in powder charges if it is above 0.2 gr I would start care. For the pistol rounds, crimping, FCD and OAL are very secondary factors unless you are seriously overcrimping or OALing it beyond any reason. Actually I prefer FCD it seems reduce seating depth variations (no clinical studies though and might be pure placibo effect).

I also suggest to have at least light crimp. Because if there is no crimp a dirty feed ramp may create enough resistance to push the bullet in ( I saw such cases). As a result you may accidentally to get an high pressure round. Depending on your load it might be dangerous.

And to your other question - cast bullets are usually more accurate. Though for larger calibers the effect seems more pronounce. For 9mm I personally don't feel much of the difference between decent FMJs and commercial casts.

?

I'm not sure why this comment was directed at me. I told him to mess around with a few adjustments if he didn't want to change bullets. But, ultimately, I told him to try other bullets.

Jacketed bullets are great, but you can get accuracy that is on par with them for much less with coated.

The FCD is useless. If you know how to size and seat bullets the FCD does nothing of any value and will likely harm accuracy.

[actionwatcher]

?
I'm not sure why this comment was directed at me.

It wasn't. You suggested one thing I suggested another to the topic starter. I think changing the bullets is a much faster and easier way to identify the problem. That was the original question, wasn't that?

The FCD is useless. If you know how to size and seat bullets the FCD does nothing of any value and will likely harm accuracy.

I don't have hard evidence to for or against FCD. It seems that OAL variations slightly smaller but it might just seem to me. But it definitely not worth than crimping and seating in the same station.

Anyway I partially use FCD for convenience. I never sweat over accuracy of pistol rounds anyway. But I haven't notice accuracy changes when I use/don't use FCD.

[CalTeacher]

It wasn't. You suggested one thing I suggested another to the topic starter. I think changing the bullets is a much faster and easier way to identify the problem. That was the original question, wasn't that?



I don't have hard evidence to for or against FCD. It seems that OAL variations slightly smaller but it might just seem to me. But it definitely not worth than crimping and seating in the same station.

Anyway I partially use FCD for convenience. I never sweat over accuracy of pistol rounds anyway. But I haven't notice accuracy changes when I use/don't use FCD.

Yeah. I suggested changing bullets.

Accuracy is important to me...thus why I won't use a FCD. I shoot over 1k rounds per month in competition and I don't have time for crap ammo.

[actionwatcher]

I would suggest that switching to an FMJ yielding positive results means nothing. More than one root cause for bad accuracy might show better results with an FMJ (or even Barnes) bullet. Such as changing bullet weight, changing bullet dimension, and changing bullet base quality. Just three examples that could make all the difference, and the old bullet might be cast, plated, or jacketed.

I don't disagree. It is just the bullet is one of the largest and in case of plated bullets one of the most probable contributors to accuracy or rather lack of thereof.


Just BTW:
Bullet makers tells us that FMJ is easier to make more consistent than plated. That why it is hard to make match bullet using plating technology. I never knew that I learned that from them and I choose to trust them because what I see correlates with what the bullet makers say.

Yeah. I suggested changing bullets.

Yes, you did