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GENERAL => Ammunition, questions, and handloading techniques => Topic started by: wdfwguy on June 28, 2018, 10:04:18 AM

Title: Different diameter 9mm bullets
Post by: wdfwguy on June 28, 2018, 10:04:18 AM
I recently ordered some 9mm bullets from Eggleston, and I noticed they offer .356, .357 and .358 dia bullets.  I've also seen .355 9mm bullets.

Just wondering who's experimented with your CZ and if you've seen any improvements in accuracy with a particular size. 

https://www.egglestonmunitions.com/



[Mods added web address]
Title: Re: Different diameter 9mm bullets
Post by: painter on June 28, 2018, 10:49:12 AM
The different sizing options are barrel dependent, and are necessary to prevent leading with lead, and coated bullets.

Typically FMJ projectiles are .355, plated tend to be sized at .356, and lead is available in many sizes to ensure a good gas seal in the bore.

Which size you should use can be determined by slugging your barrel, or listen to James and just go with .358.
Title: Re: Different diameter 9mm bullets
Post by: IDescribe on June 28, 2018, 07:17:59 PM
... or listen to James and just go with .358.

 ;D  Pretty much.

I shoot larger than standard in both jacketed and lead in my 75.  The gun definitely shoots more precisely with oversized bullets  - - .356 for jacketed and  .357 for coated lead.
Title: Re: Different diameter 9mm bullets
Post by: Wobbly on June 29, 2018, 08:03:01 AM
Where the CZ is concerned, it's far more important to understand how the ogive shape plays in the CZ chamber.... then you can worry about diameter.

 ;)
Title: Re: Different diameter 9mm bullets
Post by: MadDuner on June 29, 2018, 08:11:48 AM
I've seen no difference in accuracy between .355 and .356 plated bullets.  I have not tried anything else yet.
Title: Re: Different diameter 9mm bullets
Post by: wdfwguy on June 29, 2018, 05:22:33 PM
Where the CZ is concerned, it's far more important to understand how the ogive shape plays in the CZ chamber.... then you can worry about diameter.

 ;)

I understand in concept, especially in relation to overall length.  But maybe you could expand a little on what you're saying?
Title: Re: Different diameter 9mm bullets
Post by: 1SOW on June 29, 2018, 08:41:36 PM
^^^^^^ Even a very long RN bullet with a conventional curved ogive,  can usually be loaded as long as will fit into the magazine  or SAAMI maximum length.
 
Many or even most conical nose flat point or HP bullets will likely need to be loaded unusually short to fit into the CZ chamber without contacting the sidewall or rifling..

The abrupt change from straight bullet  side wall to conical nose shapes exposes a lot of vertical bullet sidewall that often contacts the chamber wall or leade "before seating on the case mouth".

Bullet diameter matters, bullet length matters;  but nose  SHAPE matters with any  length or diameter bullet



Title: Re: Different diameter 9mm bullets
Post by: 2APRO on June 29, 2018, 09:00:25 PM
The different sizing options are barrel dependent, and are necessary to prevent leading with lead, and coated bullets.

Typically FMJ projectiles are .355, plated tend to be sized at .356, and lead is available in many sizes to ensure a good gas seal in the bore.

Which size you should use can be determined by slugging your barrel, or listen to James and just go with .358.

^^^^^^^ This. Slug your barrel. I've found that .001" to .002" (typically .002" works better in my CZ) larger than what the barrel slugs at works the best for me. One exception is Blue Bullets. The 147g RN I use measures at .355" and shoot lights out in my SP01. Not sure why, but this bullet seems to be an exception.
Title: Re: Different diameter 9mm bullets
Post by: Wobbly on June 30, 2018, 07:50:58 AM
I understand in concept, especially in relation to overall length.  But maybe you could expand a little on what you're saying?


(https://lh3.googleusercontent.com/7Kp7G91X9c3Bhl00slPBze5oiBB-PAFjSAfKXX0frJzTGNqIi865MNFHh-DGj_rpyxwmXZzUZGl03LyzHmNPX3dROx1p5hXHX0ilps3NNTWNQ-9D_7dwXIhvgH5ODpB59-mzCKd9TjxqbO1XBInEeMDbrBuup_tSoeEUuZ7UCFonVS1ofRuLvUvOjur0z-n36DgJ4_21y2OzBMmKBzxrQvS2T-I7LpIAp2GnvX5RqRhKCK8zxdidbOb0LC00H11tjxCqWlMrsUmkRkHXex5DZVKQMYpt24Y-7Xhr5DygF986CQ__lTMfqRtUCmIjWMLbXj__TDXlqSCj5qnQWkGHyCDsFZfiFDNC0coyOc77lZ_XMppdnBELpa_fv5iIHUv5vVOkzO6qLXQHtDRpQbpfMswDUML-ClecGghinNFfvHsFi7KpO8rE3e_iJJaqIuwRV4UbNQ5hVhaZKow0B--QyarBj0ndsssezvTQmMvQI4Mwe1UIC3Jxek07_GED69fGXzXJnl2KXmB1t1WbHnFmwoZ1GEp1-0jajrB3i3jF7YKHw8AbN4iN9ImYXdfR21GVzMpC5qUCj197X4kikxsTMrewtm5c-fqCMJVoiQY=w810-h605-no)

These bullets look fairly similar, especially when you see them in 2 different catalogs. However, in a standard CZ SP-01 and P-01 the bullet on the left has a Max OAL of 0.990" (under the minimum OAL suggested for 9mm by SAAMI), while the one on the right supports a Max OAL of 1.220" (which is much longer than what the magazine will accept).

? The point is, not every bullet for sale can be successfully reloaded for use in the CZ chamber.

Unfortunately, I had already bought 1K of the bullets on the left before I discovered this. Those ended up with a pal with a Glock after I sold them for less than I paid the week before. You'll come out a bit better than I did. The Eggleston will do OK, but the Max OAL may end up shorter than you planned on (or what your manuals give load data for), and so a lot of load development may be required.

? Suggested reading: How to Determine Max OAL (http://www.czfirearms.us/index.php?topic=34225.0)

 ;)
Title: Re: Different diameter 9mm bullets
Post by: wdfwguy on June 30, 2018, 05:34:46 PM
In regards to bullet shape, I have found that conical or flat nose bullets are more accurate in my Shadow than RN
Title: Re: Different diameter 9mm bullets
Post by: MadDuner on June 30, 2018, 06:56:59 PM
I wonder if that's because they have more "side" to them to maintain "straight" out the barrel?
Title: Re: Different diameter 9mm bullets
Post by: IDescribe on July 01, 2018, 12:01:41 AM
Profile of the nose has no impact on accuracy at subsonic speeds.  NOW, if you're talking about jacketed bullets, there's a difference between FMJ vs JHP, but it has to do with which end they're swaged into.  That's a different dynamic, though -- it's not about the shape of the nose.
Title: Re: Different diameter 9mm bullets
Post by: wdfwguy on July 01, 2018, 01:06:26 AM
Bullet shape has an impact on accuracy in my Shadows, I guess ymmv
Title: Re: Different diameter 9mm bullets
Post by: jameslovesjammie on July 01, 2018, 09:49:17 AM
Bullet shape has an impact on accuracy in my Shadows, I guess ymmv

It is possible that bullets with different nose shapes can have different accuracy results, but there are other several factors that are figured in when you change bullets.   Bearing surface length, changes in the bullet's center of balance compared to the center of pressure, consistency in manufacturing, sizing diameter, base design, etc all play a roll in how accurate a bullet will be.


That's a different dynamic, though -- it's not about the shape of the nose.

According to ballistician Meghan Trainor, "Because you know I'm all about that base, 'bout that base, ...in fine fettle!"   ;D  I agree with you.  While the profile of the nose makes a difference in how well a bullet feeds, the base of the bullet is more important to be free of defects/dings/damage for shot to shot consistency.
Title: Re: Different diameter 9mm bullets
Post by: IDescribe on July 01, 2018, 11:20:17 AM
wdfwguy, try to read all of it.  I know it's long, but there's some stuff in there you might find useful.  :)


A fundamental mistake I see in the forums again and again and again is viewing correlation as causation.  People spot a trend, they notice a commonality in the loads active in that trend, and they assume that commonality is the source of the trend.  That's a fine place to envision and begin testing, but when we just rest on that assumption, confirmation bias will reinforce that assumption whether it's accurate or not.  I've been victim to it, and I see others victim to all the time.

In your case, all you can accurately say is that the conical and/or flat nose bullets you have loaded have been more accurate than RN as you have loaded them.  That doesn't mean that the shape of the nose contributed to the accuracy.  That doesn't mean that there are no RN bullets out there that could surpass your best conical flat nose bullet in your Shadow.  And it doesn't mean that even with the RN bullets you've loaded, you couldn't have tuned them to be more accurate than your most accurate conical flat nose bullets.  What you've observed is a correlation between two general data points, then assumed the relationship between the two was causal.

For a particular feature or characteristic of a bullet to be ballistically relevant, it needs to interact with something.  That's a fundamental fact.  Two things that people often cite as contributing to accuracy are bullet profile, as you have, and a specific OAL.  "My gun likes OAL 1.15."   WHAT?!?!?!?   That makes no sense.  But I see it with regularity.  The gun couldn't care less how far the nose is from the headstamp once the powder ignites.   The same can be said for nose profile.  The shape of the nose of the bullet does not touch the gun.  It doesn't interact with the barrel or gun during firing.  Now, nose shape might contribute to accuracy in flight at supersonic speeds. At supersonic speeds, the bullet creates a dome-shaped bow wave of compressed air, and the nose of the bullet does interact with that bow-wave, and that interaction has a stabilizing effect on the bullet.  The stronger the interaction, the greater the stabilizing effect, and in those cases, because the shape of the RN nose more closely matches the shape of the bow wave than any other profile, it's the RN bullets that have the stronger interaction and benefit more from that interaction.  At subsonic speeds, however, that interaction doesn't exist, and the shape of the nose of the bullet is irrelevant.  At subsonic speeds, wadcutter, semi-wadcutter, RN, CN, FP -- it doesn't matter.  And if it doesn't matter in flight, and it doesn't interact with the barrel, it doesn't affect accuracy.

MadDuner mentioned that maybe the FP bullets having more "side" to them to maintain "straight" out of the barrel.  That "side" he mentioned, commonly referred to as bearing surface or shank, does interact with the barrel, and the length of the shank does have a ballistic effect.  I would suggest that with proper bullet to barrel fit, the length of the shank isn't going to mean much for accuracy, but at least there's some ballistic effect there, and it does affect center of mass.  The thing is -- even if that did contribute heavily to accuracy, it wouldn't be the shape of the nose causing it -- it would be the shank length, and while you might say "But wait, it's the RN nose that requires the extra shank length," it's actually not. There are plenty of short stubby RN profiles, as short and stubby as the truncated cones we're talking about, with similar or even longer shank lengths.  So while it might be true that the RN bullets Bob D'Reloader has loaded have shorter shanks than the conical nose flat points that he's loaded (let's just call them truncated cone flat points(TCFP)), that's just the ones he's loaded, and not RN vs TCFP universally. 

So why might you be seeing your TCFP bullets performing more accurately than RN?  It could be that because of the interaction between profile and rifling, that you are seating the base of the bullet deeper into the case with the TCFP.  This is specific to the bullets you've loaded, and not universal, but it's not uncommon for this to be the case comparing the two profiles.  This deeper seating has a few ballistically relevant effects. 

The first is that by getting more bullet into the case, you are improving runout (the misalignment between the bullet axis and the case axis). Now, you will experience diminishing returns on that improvement, so getting the bullet base .150 into the case from .100 creates a greater improvement than seating from .150 to .200, which creates greater improvement than going from .200 to .250, and so on.  BUT a lot of RN bullets will seat long enough that the base ends up around .170/.180 into the case, where most TCFP (I'm specifically talking 124/125gr bullets here, if you go up to 147gr, these numbers all get higher)  most 124/125gr TCFP will need to be seated down to .240/.250 into the case in order to chamber properly in a CZ.  The same is true for JHP.    But those differences alone, by decreasing runout, by improving alignment of the bullet and case axis and bullet axis, you are also improving alignment of the bullet axis and bore axis at the moment of engagement, and THAT affects accuracy/precision.  At what depth is it deep enough that deeper doesn't help any more?  I don't know.  I can't tell you that.  I am offering possibilities here. If you are seating a TCFP as long as you can, and an RN as long as you can, it is quite possible that all the TCFPs you've loaded have had the advantage in this regard.

A secondary issue with seating depth, OAL, and runout is the possibility of misalignment getting worsened during chambering, when the exposed bullet is getting knocked around as it strikes the feed ramp and then roof of the chamber as it's being slammed home. The nose of the bullet is getting levered against the case the whole way.   And the further the nose is from the case mouth, the greater the leverage.  I do NOT know how deep into the case is deep enough vs a specific OAL, to negate this, or even if at any practical seating depth and OAL there is a measurable effect at pistol distances, but it's a possibility.  If you are seating a TCFP as long as you can, and an RN as long as you can, it is quite possible that all the TCFPs you've loaded have had the advantage in this regard.

A third effect of seating depth is related to the length/height of the powder column, as well as case fill.  How the powder charge sits in the case affects the burn.  One of the means to improve consistency across a chrono is to tilt the gun backward before each shot, making sure that the powder is sitting in the case as consistently as possible from shot to shot.  The shorter the powder column and the greater the case fill, the more consistent the powder will sit from shot to shot, and the more consistent the burn.  If you are seating a TCFP as long as you can, and an RN as long as you can, it is quite possible that all the TCFPs you've loaded have had the advantage in this regard.

A fourth effect with seating depth is that as seating depth increases, the initial size of the combustion chamber is decreasing, and that affects the rate at which the powder burns and pressure increases.  This can be especially important in the first moment of the burn.  When the powder ignites and starts to expand in volume, it presses the case walls out against the chamber walls and creates a pressure seal.  This seal prevents burning and unburned powder and gases from escaping between the case walls and chamber walls and being blown back into the pistol where they don't drive the bullet.  It also affects the fuel-air mixture.  The faster the burn, the faster this seal occurs, so the deeper the bullet is seated, the smaller the initial size of the combustion chamber, the faster the burn, the faster the seal occurs, and the more consistent the burn is from one shot to the next.  If you are seating a TCFP as long as you can, and an RN as long as you can, it is quite possible that all the TCFPs you've loaded have had the advantage in this regard.  ;)

SO... you might be thinking "Wait a minute, ID just described four things that make TCFP more accurate than RN," but that's not the case.  I described four ballistically relevant things that MIGHT affect accuracy based on seating depth, the depth the base of the bullet is seated into the case.  The truth is that there are RN bullets that would accomplish the same or similar or better dynamics than any TCFP you've used at their max OAL, BUT...

AND MORE IMPORTANTLY, most RNs can accomplish the same thing simply by reducing OAL to make those other numbers match.  There's nothing preventing the loader from shortening the OAL until the bullet base is also down to .250/.260 into the case.  In fact, there was some testing done here in these forums a few years back with RN bullets and OAL, and it was found that shortening OAL improved accuracy.  This is in direct contradiction to the precision rifle rule of thumb that the longer you can load, the closer you can get the bullet to rifling, the better the accuracy, but like so many other reloading considerations, the best loading choices for a bullet to be shot 500-1000 yards isn't necessarily the best loading choice for a bullet being shot at 7-35 yards.  There's a reloader at Benos named Darrel, one of the most prolific, data-collecting, load testing reloaders I've seen, and I just saw him saying a week or two ago that he almost always finds better accuracy with more deeply seated bullets.

I guess the point here is that while a TCFP is more likely to force you to seat deeper and gaining the advantages therein, there's nothing stopping you from seating even a long-loading RN deeply, as well.  The ballistic differences there are a matter of tuning, not a matter of profile.

I also have no idea what bullets you're loading.  If you told me, for example, that you'd loaded the Blue Bullets 147gr RN and the ACME 147gr TCFP, and the ACME TCFP were more accurate, I'd tell you the difference is bullet to barrel fit.  Blue Bullets are undersized.   If you told me you'd run the ACME 145gr RN and the BBI 147gr TCFP, and the flat point did better, I'd tell you that the BBI is over-sized, and clearly your gun prefers oversized.  ;)   Bullet fit is HUGE.  And even differences in bullets from the same company can affect results.

I also mentioned jacketed rounds in the last post.  The last moment of interaction between the pistol and bullet is between the bullet base and the barrel crown.  Damage to the crown affects accuracy negatively, and so can imperfections in the bullet base.  FMJ-RN and FMJ-FP bullets are swaged into the nose.  It's the noses of those bullets that will be closest to perfect.  JHP are the opposite -- JHP are swaged into the base, and it's the JHP's base that will be closest to perfect.  With jacketed bullets, this gives JHP the advantage, at least at pistol distances.  But it's the JHP's perfect base that gives it the advantage, not the nose.  And to be clear, this is because of the process of swaging.  Most of the coated lead, lead, and plated bullets we use are cast, not swaged, so this is irrelevant for those bullets.


ANYWAY...

There are ALL sorts of variables that contribute to accuracy, and at subsonic speeds, nose profile isn't one of them.  :) 

And at supersonic speeds, RN has the advantage.

Unless we're talking jacketed, in which case JHP have the advantage -- because of the base.  ;)

Cheers, sir.  :)
Title: Re: Different diameter 9mm bullets
Post by: IDescribe on July 01, 2018, 11:24:16 AM
According to ballistician Meghan Trainor, "Because you know I'm all about that base, 'bout that base,

That song is a guilty pleasure of mine. But yes, all about that base.    ;D

And let me see if I can find a hip-hop song on bullet to barrel fit.  ;)
Title: Re: Different diameter 9mm bullets
Post by: wdfwguy on July 01, 2018, 11:47:15 AM
Interesting....

I only had time to just skim your post, but I'll go back later today and give it my full attention.  I'm always up for learning something new.

 :)
Title: Re: Different diameter 9mm bullets
Post by: MadDuner on July 02, 2018, 08:11:26 AM
Thanks for the write-up Idescribe!

I will have to read it 4 more times before I can fully appreciate it though.

I am also interested in what - if any difference in accuracy can be attributed to powder burn rate?

Title: Re: Different diameter 9mm bullets
Post by: Wobbly on July 02, 2018, 09:00:31 AM
Thanks for the write-up Idescribe!

I will have to read it 4 more times before I can fully appreciate it though.


That's why we pay him the big bux.
Title: Re: Different diameter 9mm bullets
Post by: wdfwguy on July 02, 2018, 11:07:46 AM
To sort of get back on topic...

I think I'll order a sample pack on the Egglestons in .356, .357 and .358

I'll load them up identically and see if there's any difference in group size
Title: Re: Different diameter 9mm bullets
Post by: SoCal on July 02, 2018, 08:07:51 PM
To sort of get back on topic...

I think I'll order a sample pack on the Egglestons in .356, .357 and .358

I'll load them up identically and see if there's any difference in group size

Good idea just remember that when you load the .358 to make sure you have enough bell on the case mouth that you do not shave the coating (been there, done... well you know the rest of the story).
Title: Re: Different diameter 9mm bullets
Post by: IDescribe on July 02, 2018, 09:52:26 PM
Also, I don't recall what weight you're accustomed to shooting, but I'd stay down at the 124/125 range.   If you go to .358 on a 147, you may have trouble with its needing to be seated TOO deep when OAL is short enough to fit the CZ chamber.
Title: Re: Different diameter 9mm bullets
Post by: wdfwguy on July 02, 2018, 10:05:55 PM
I'm generally shooting 124/125s
Title: Re: Different diameter 9mm bullets
Post by: IDescribe on July 02, 2018, 10:36:32 PM
Fixed a type-o.  Too DEEP.  Too DEEP.  ;)
Title: Re: Different diameter 9mm bullets
Post by: Wobbly on July 03, 2018, 08:53:00 PM
Too DEEP.  Too DEEP.  ;)


That's two DEEP.    ;D
Title: Re: Different diameter 9mm bullets
Post by: IDescribe on July 03, 2018, 11:37:18 PM
...if any difference in accuracy can be attributed to powder burn rate?

Not really??? 

There are plenty of faster powders that produce great accuracy.  And some not great.  There are plenty of slower powders that produce great accuracy.  And some not so great.  The two or three powders with the best reputation for accuracy in 9mm are slower powders (not THE slowest), but that's not the same as saying slower burn rates are more accurate. 

If you aren't going to name the powder, burn rate doesn't tell you anything, and if you DO name the powder, burn rate doesn't matter.  ;)

You would never want to assume you want a slower powder for better accuracy. ;)
Title: Re: Different diameter 9mm bullets
Post by: MadDuner on July 04, 2018, 10:27:21 AM
...if any difference in accuracy can be attributed to powder burn rate?

Not really??? 

There are plenty of faster powders that produce great accuracy.  And some not great.  There are plenty of slower powders that produce great accuracy.  And some not so great.  The two or three powders with the best reputation for accuracy in 9mm are slower powders (not THE slowest), but that's not the same as saying slower burn rates are more accurate. 

If you aren't going to name the powder, burn rate doesn't tell you anything, and if you DO name the powder, burn rate doesn't matter.  ;)

You would never want to assume you want a slower powder for better accuracy. ;)

Fair enough.
I've been using either Unique or TiteGroup in my 9mm loads. I appear to have better accuracy with Unique - even though I can plainly see that the powder quantity of my loads cannot be as consistent as they are with TiteGroup.

I also have not seen any difference in accuracy between Berry's .356 projectiles and Extreme's .355 or Blue Bullet's .355s - all RN.

 I'm about out of powder and will need to restock.  What should I try next?
Title: Re: Different diameter 9mm bullets
Post by: IDescribe on July 04, 2018, 11:59:13 AM
I also have not seen any difference in accuracy between Berry's .356 projectiles and Extreme's .355 or Blue Bullet's .355s - all RN.

I don't either, but mostly because I don't see top notch accuracy from plated bullets, period.  And Blue Bullets standard .355 sizing is undersized for 9mm, which reduces precision in a barrel that prefers standard or over-sized, so I would assume your barrel in that group.  ;)

ACME is top notch.  BBI is top notch.  Blue Bullets are also great bullets, generally speaking, and they now offer special order bulk packages of bullets sized .356, and we've always had the option of buying their .38/.357 bullets sized .358, which some here have used with great results.


I'm about out of powder and will need to restock.  What should I try next?

I have plenty of answers, but probably best for you to start your own thread titled "Powder Opinions for 9mm for  ___________________"  where the __________________ is occupied by whatever application you plan on using the load for -- 9mm minor action pistol, ultimate accuracy out to 50 yards, lowest recoil possible Steel Challenge, plinking, Self-defense, etc..   I'd answer here, but every time I derail a thread, Wobbly overnights me a venomous snake, and I think Georgia is running out of venomous snakes.  ;)
Title: Re: Different diameter 9mm bullets
Post by: coues52 on July 04, 2018, 12:36:30 PM
  great read on this  post..esp IDescribe article..Thank you..Danny B
Title: Re: Different diameter 9mm bullets
Post by: Wobbly on July 06, 2018, 07:54:25 AM
I'd answer here, but every time I derail a thread, Wobbly overnights me a venomous snake, and I think Georgia is running out of venomous snakes.  ;)


Just the rattlers. We got plenty of copperheads left.

 O0