9mm barrel size vs bullet size

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santacruzdave

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Finally got around to slugging my 9mm pistol barrels. I'm not all that experienced reloading and I wanted to gather some information on why some of my reloads are way more accurate than others. So I slugged the bores of my 4 pistols and wound up with 2 measuring .3565 and 2 measuring .3545.

I shoot coated lead bullets primarily. Dug thru a few manuals and found the following recommendation for accurately sizing lead bullets in the Lyman 50th Edition reloading manual, "If the first tests [bullet diameter = bore diameter] do not provide the desired accuracy, a second series of attempts can be with bullets sized 0.001" larger. A third sequence can be with bullets 0.002" larger. It is counter productive to use any larger sizing diameter."

Lee's Modern Reloading 2nd edition does not recommend (that I can find) a specific size range as the Lyman manual does. Lee does state that "The problem of excessively large bullets is not exactly what one would expect." Lee goes on to explain that these large bullets will not cause excessive pressure, but will cause chambering problems especially with cases that have thick walls. So it appears that bullets so large as to cause excessive pressure would cause the case to become too large to chamber, and therefore the problem over pressure with oversize bullets is self eliminating.

My most accurate coated lead handload to date is a 122 gr ACME Truncated Cone, COL of 1.040, over 4.5 gr of CFE-Pistol shot out of a CZ SP-01 with a slugged bore of .3565. I measured the 122 gr ACME at .356. The attached photo is 50 rounds of this load shot at 10 yards off hand. I'm happy with these results.

Would you call this good? Do you think it would be productive to experiment with a slightly larger bullet, say a .3570. Have you slugged your barrel and did you find one size bullet to be more accurate than another?


122ACME4.5CFEP.jpg
 
Looks good to me.:)
Only you can decide if a certain level of accuracy is good enough for your use.
I tend to like slower powders for 9mm like WSF (CFE-P is about the same or maybe a hair slower) even if I am loading medium power loads
It might be interesting to see what a slightly larger bullet would do but you may have issues finding production bullets at .357, as lead bullets for .38/.357 are usually .358.
I sure some one here knows where you could get some sized to .357.

If it was me and I wanted to try something different I would stick with the bullet you are using that seems to be working well for you and maybe try a powder with a little faster burn rate, something like Sport Pistol
 
Funny how I could not get an accurate load for the SP-01 with Sport Pistol. I had all but given up on lite to mid loads with CFE-P in 9mm and only loaded the above load to check the metering of my rebuild of a Hornady powder drop. What got me to finally slug these barrels was the availability of .356, .357, 358 and .359 125 gr bullets from Brazos Bullet Co. in College Station TX. I shot a bunch of their truncated cone .357 in 357 magnum, no reason why they should not work in 9mm. They also have 125 gr RN in .355, .356 and .357.
Have not loaded any in 9 yet.
 
Does Brazos Bullet Co. sell coated bullets, santacruzdave? All I see on their website is uncoated lead.

Update: never mind, I found the coated ones.
 
Funny how I could not get an accurate load for the SP-01 with Sport Pistol. I had all but given up on lite to mid loads with CFE-P in 9mm and only loaded the above load to check the metering of my rebuild of a Hornady powder drop. What got me to finally slug these barrels was the availability of .356, .357, 358 and .359 125 gr bullets from Brazos Bullet Co. in College Station TX. I shot a bunch of their truncated cone .357 in 357 magnum, no reason why they should not work in 9mm. They also have 125 gr RN in .355, .356 and .357.
Have not loaded any in 9 yet.
Lee sizing dies would help here

That is what led me to buy only bullets that are 0.358" dia for both loading 9mm and 38/357, or even 0.359" diameter when I find them.
I buy coated bullets with no crimp or lube grooves/RN or TC/all weights, and I can push them thru a Lee sizing die a diameter to suit the gun I'm loading for.
Some 9m barrels have "tighter" chambers than others so I need to sort cases by brand and use the thinnest stuff when loading 0.358" bullets for those chambers.
For me, buying bullets one diameter and sizing them to the gun, whether 9mm or 38/357 cuts way down on bullet inventory but I needed to buy 3 Lee sizing dies (0.356"/0.357"/0.358") at a cost of about $20 each.
works for me,
:D
Edit: Forgot to mention the reason for the no-groove bullets, they feed best thru a Hornady bullet feeding die. :uhoh:
 
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Does Brazos Bullet Co. sell coated bullets, santacruzdave? All I see on their website is uncoated lead.

Update: never mind, I found the coated ones.
They are hiding them well, haven't found them yet.......
 
Lee sizing dies would help here

That is what led me to buy only bullets that are 0.358" dia for both loading 9mm and 38/357, or even 0.359" diameter when I find them.
I buy coated bullets with no crimp or lube grooves/RN or TC/all weights, and I can push them thru a Lee sizing die a diameter to suit the gun I'm loading for.
Some 9m barrels have "tighter" chambers than others so I need to sort cases by brand and use the thinnest stuff when loading 0.358" bullets for those chambers.
For me, buying bullets one diameter and sizing them to the gun, whether 9mm or 38/357 cuts way down on bullet inventory but I needed to buy 3 Lee sizing dies (0.356"/0.357"/0.358") at a cost of about $20 each.
works for me,
:D
Edit: Forgot to mention the reason for the no-groove bullets, they feed best thru a Hornady bullet feeding die. :uhoh:

NOE makes a much better sizing system that actually measures to what they are marked, unlike Lee. http://noebulletmolds.com/NV/index.php?cPath=564&osCsid=gekqphk6bp746d7cuqug944n11

My Canik TP9SFX needs .357 bullets. So I just size all my 9mm bullets to .357. They work just fine in my 5906, Ruger PCC, Sig P365, and hopefully my RIA.

One tip, when slugging a bore make sure to use a micrometer to measure the slug and not calipers.
 
First off, if it ain't broke, don't fix it.

Second - I shoot the Lee 358-125-RF, sized .358, from several 38spl/357mag revolvers.
I shoot the same projectile, still sized 358, in several 9mm pistols.

If it will chamber, it will shoot.
yep, except when it won't chamber...
I hate pulling bullets and after recently switching to wet tumbling I was amazed at what I saw inside of range brass.

So now I cull brass before loading to avoid the need to pull bullets, but will confess, I only have one 9mm barrel with a tight chamber that requires smaller than 0.358" bullets and thin walled brass.:uhoh:
Some recently culled 9mm cases, tossed instead of loading:
index.php

index.php

:D
 
yep, except when it won't chamber...

index.php

index.php

:D

For whatever reason, I can't see your pics.

No matter -

With 9mm brass being ubiquitous, I have taken to sorting by headstamp. I pitch the oddball brass, and whatever headstamp has given me problems previously, into the recycle bucket.
I don't load mixed brass, and have fewer problems with chambering.
 
When I acquired a gun with a tight chamber (Dan Wesson PM-9), I found that about 1% of my reloads would not chamber. I was using the usual 4 die solution (size, expand, seat and crimp). Most of my brass was from Glock Gen3/4. To resolve my issue I did 3 things differently. 1) Obtained a Lee U (undersize) sizing die set to resize the entire case, 2) Check every round with Lyman size gauge 3) stopped using the crimp die. This gave me a 100% solution for all of my guns. Two side effects were that coated bullets were shown to have coating not damaged on pulling the bullet, I could reduce the load by .1-.2 and get better accuracy. This works for the brass that has a heaver base (e.g. thicker wall in bottom portion).
 
I bought a tight chambered EMP and had to start gauging sized brass. If it fits in and falls out of it's own weight, it will fit in the EMP chamber. I scrap all sized cases that don't pass. No worries after that. Some cases fail by a little, but some fail by a mile. I lose about 10% to 15% when sizing range brass. When sizing my own fired cases from previously sized/gauged/loaded brass I seldom lose any from failure to fit the gauge. That is another good way to make sure pressure isn't to high as well.

Wilson 9MM Case Gauge Pic 1.JPG

If it passed the gauge after sizing, it always passed after loading.
Wilson 9MM Case Gauge With Bullet.JPG
I don't even check them after loading anymore.

A standard Lee sizer with the long tapered carbide insert.
 
You are more than welcome to crunch all the data you like, however, after all the numbers settle, and you have driven yourself nuts when the data and shooting data dont mesh....keep in mind

Some guns just flat shoot better than others for no real rhyme or reason.
 
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