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Bullet diameter question


Jsjac
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I have been shooting .356" diameter 9mm coated bullet.

 I have been looking at the Blue Bullets and their bullets are .355". 

 Is the one thousands of an inch going to make a difference.

I have ordered a small batch of their .355 and .356 bullets to try. 

 Just wondering if people are ordering the standard size Blue Bullets or ordering the special order .356 size bullets?

 

I am thinking of switching to the Blue Bullets to get a steady order of bullets coming every month with their subscription service. 

 

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Compare them in your gun/guns and find out.  That's the only way to know.  

For me there was a slight difference.  Shooting 10-shot groups at 25 yds, the 0.355 bullets would mostly have a nice 2" or so group with 1 or 2 shots being a little further out making it a 3" or 3.5" group, when most were in the 2" group.  The 0.356 bullets kept everything in a nice 2" group for me, no little flyers.

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ive been shooting blues for a while....i was pretty sure that their bullets were .356

 

in either case when your shooting lead 1/1000th over is what you want because the lead will deform as it moves down the barrel which, if its too small will lead to pressure loss. 

 

i shoot 38 sc with a .355 barrel. and ive been using their .356 blues for a while with no negative effect.  If you were to shoot a true .355 out of a .355 barrel you could expect pressure and velocity loss since it would not make a complete seal

 

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Your barrel will tell you which diameter it likes best.  Simply load both, and see if one shoots better for you.  We usually shoot loads on the light side for action pistol games, and with those, you are unlikely to have any serious pressure issues develop.  

 

You can also slug your barrel to determine bore and goove diameter, and most advise using bullets at least 0.001" over groove diameter.  Meister sells slugging kits you can slug your barrel with, and then use a good micrometer to measure the result.  Good info here:  https://www.meisterbullets.com/slugyourbarrelsdetails.asp  

 

This kit is what I use for 9mm barrels:  https://www.meisterbullets.com/AWSProducts/306-C-24-P-0/Slug-Kit-5-Flat-Rate-Included 

 

Believe it or not, I bought one 9mm barrel that actually slugged over 0.3565"!  It was returned for a refund...  

 

If you just want the "CliffsNotes" version, I would recommend using 0.356" lead bullets over 0.355" for 9mm...  JHP 9mm's in 0.355" diameter usually work fine, but coated (and even plated for that matter) 0.356" bullets seem to always work better for me.  The larger lead bullets are less prone to gas cutting of the base, which can lead to inaccuracy and barrel leading issues.  A JHP doesn't have exposed lead on the base, and so gas cutting usually isn't a problem.  

 

I have experimented with 0.357" and 0.358" diameter bullets in 9mm, but that is probably best left for the "advanced" class!  With some seating depths and some brands of cases, it can be difficult to get those to even chamber...  Not to mention to possiblity of pressure spikes!  

 

YMMV...  The above is my own opinion, and please feel free to take it or leave it as you choose.  

 

 

Edited by Ken6PPC
typo
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Slug your barrel and add .001. Use fishing weight lead cast into a 9mm brass and pull it out with a bullet puller. Run it through your barrel, mic it up and add .001 for your final coated bullet dia.

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1 hour ago, Ken6PPC said:

 

Believe it or not, I bought one 9mm barrel that actually slugged over 0.3565"!  It was returned for a refund...  

 

 

Believe it or not, 0.3565" is within SAAMI specs.  The SAAMI specs for 9mm barrel groove diameter is anything between 0.355" and 0.359". 

https://saami.org/wp-content/uploads/2019/02/ANSI-SAAMI-Z299.3-CFP-and-R-Approved-2015-12-14-Posting-Copy.pdf

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12 hours ago, superdude said:

 

Believe it or not, 0.3565" is within SAAMI specs.  The SAAMI specs for 9mm barrel groove diameter is anything between 0.355" and 0.359". 

https://saami.org/wp-content/uploads/2019/02/ANSI-SAAMI-Z299.3-CFP-and-R-Approved-2015-12-14-Posting-Copy.pdf

 

Perhaps that is acceptable for SAMMI...  They are primarily concerned with safety. 

 

Such a large overbore as 0.359" groove diameter may be SAFE, but it is doubtful to be accurate.  One would need 0.360" diameter lead bullets to prevent gas blow-by, and they would probably be difficult if not impossible to load in a case AND fit a standard chamber.  One could go with a wildcat chamber, but then it wouldn't be a SAMMI 9mm Luger, would it?  

 

Here is what the groove diameter fpr a 9mm Luger is SUPPOSED to be:  

Annotation 2020-07-04 095226.jpg

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11 hours ago, 36873687 said:

I order .356 in kkm barrels 2011 an pcc an cz

 

Why would you?  

 

Not being sarcastic...  I would really like to know the logic of that decision.  

 

Do you shoot lead bullets, plated, FMJ, or JHP?  What diameter?  

 

 

Edited by Ken6PPC
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See the lower part of the page in green.  

 

I've slugged over a dozen 9mm barrels and only 2 of them have been less than 0.356". I also have not noticed any evidence that jacketed bullets smaller than groove diameter are less accurate. I haven't looked at this with lead bullets, so I can't comment on that.

 

 

 

 

 

Edit: I can't get rid of the extra image!!!!

image.png

 

image.png

Edited by superdude
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1 hour ago, superdude said:

See the lower part of the page in green.  

 

I've slugged over a dozen 9mm barrels and only 2 of them have been less than 0.356". I also have not noticed any evidence that jacketed bullets smaller than groove diameter are less accurate. I haven't looked at this with lead bullets, so I can't comment on that.

 

 

 

Yes, I saw that +0.004", but that isn't optimal.  That is only the maximum tolerance, and certainly not best for accuracy.  

 

I too have slugged many 9mm barrels, and any barrels that are over 0.356" do not shoot as well (with lead bullets) as do those that are closer to 0.355".  I have had chambering problems when using bullets larger than 0.356", so I use 0.356".  

 

The OP was specifically asking about coated lead bullets.  

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27 minutes ago, Steve RA said:

I use .358 (coated) and have had no problems and very good accuracy.9mm

 

This is in 9mm.

 

How do you get those to "plunk"? 

 

Do you ream your 9mm chambers oversize?  

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21 hours ago, Jsjac said:

I am thinking of switching to the Blue Bullets to get a steady order of bullets coming every month with their subscription service. 

 

 

I would not worry at all about using Blues. They are great bullets, accurate as just about any other, and have great service. 

Just find the weight and profile that works best for you.

 

BTW, I've tried .355, .356, .357 and .358 and truthfully in my Tanfoglios, CZs, Glocks, Sigs and some custom barrels I find very little difference in accuracy between them. What I did find is .357 and .358 are far harder to load and, depending on the chamber and brass, will not plunk as easily. So I use .356.

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On 7/3/2020 at 2:05 PM, Jsjac said:

I have been shooting .356" diameter 9mm coated bullet.

 I have been looking at the Blue Bullets and their bullets are .355". 

 Is the one thousands of an inch going to make a difference.

 

I guess it depends on how thick the coating is.  Assuming it's .001 then the actual bullet is .354".   Maybe someone knows the thickness for sure. 

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8 hours ago, Ken6PPC said:

 

Why would you?  

 

Not being sarcastic...  I would really like to know the logic of that decision.  

 

Do you shoot lead bullets, plated, FMJ, or JHP?  What diameter?  

 

 

Each there own Cheif. That’s what I’ve had great success with

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On 7/4/2020 at 9:30 AM, Ken6PPC said:

Your barrel will tell you which diameter it likes best.  Simply load both, and see if one shoots better for you.  We usually shoot loads on the light side for action pistol games, and with those, you are unlikely to have any serious pressure issues develop.  

 

You can also slug your barrel to determine bore and goove diameter, and most advise using bullets at least 0.001" over groove diameter.  Meister sells slugging kits you can slug your barrel with, and then use a good micrometer to measure the result.  Good info here:  https://www.meisterbullets.com/slugyourbarrelsdetails.asp  

 

This kit is what I use for 9mm barrels:  https://www.meisterbullets.com/AWSProducts/306-C-24-P-0/Slug-Kit-5-Flat-Rate-Included 

 

Believe it or not, I bought one 9mm barrel that actually slugged over 0.3565"!  It was returned for a refund...  

 

If you just want the "CliffsNotes" version, I would recommend using 0.356" lead bullets over 0.355" for 9mm...  JHP 9mm's in 0.355" diameter usually work fine, but coated (and even plated for that matter) 0.356" bullets seem to always work better for me.  The larger lead bullets are less prone to gas cutting of the base, which can lead to inaccuracy and barrel leading issues.  A JHP doesn't have exposed lead on the base, and so gas cutting usually isn't a problem.  

 

I have experimented with 0.357" and 0.358" diameter bullets in 9mm, but that is probably best left for the "advanced" class!  With some seating depths and some brands of cases, it can be difficult to get those to even chamber...  Not to mention to possiblity of pressure spikes!  

 

YMMV...  The above is my own opinion, and please feel free to take it or leave it as you choose.  

 

 

^^^^ Very sound advice.  👍

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