Brazos Bullets 9mm all Fail Plunk Test

Everyone of these Brazos 0.356" bullets in a completed round have failed the plunk test and gauge checker (EGW) test, but one single round. I'm using a KKM 1:32 barrel. I purchased a 1,000 of the 9mm 115gr Round Nose/Bevel Base/No Groove Hi-Tek rounds. 

I substituted this 0.356 hi-tek bullet with cheap-o bullets from a remanufactured round. These all work fine. Is it possible its the hi-tek coating or the 0.356" size vs the 0.355"?

Has anyone experienced this before? I'm fairly new to reloading.

Can you show us a loaded round?  I use that bullet in that barrel.  What kind of brass?  What’s your crimp?

Who built the gun? If it’s a Sams his chambers have short lead for his recommended jacketed bullet.
Jon

EGW also has two different 9mm chamber check gauges dependent on bullet profile, using your barrel is probably a better bet as KKM barrels require final chambering when fit.

KKM comes short chambered by about 0.100”. -0.150”.
They have no lead angle cut into rifling. Kart has lead angle cut and is barely short chambered 0.00”-0.010/0.015”. Your slide determines final headspace after fitting barrel; in other words how much of the hood was cut shorter to fit barrel into slide.
Jon

I bought some Brazos 9mm bullets and loaded them the same as I loaded some Acme coated bullets and had a similar problem. The Brazos bullet keeps its full diameter longer so the pointed area is thicker than the Acme bullet which caused my problem. I too had loaded up a bunch so my solution was to deepen the seating depth a little and run them all through the seating die again.  That solved my problem. 

Good luck.
John

You could take a ~0.750" long 9 mm case and cut a narrow slot about 1/2" long in three places (about 120 degrees apart) with a Dremel and thin abrasive disk. If it's done right you can then insert a bullet at the front of the case, and press it fully into the chamber, until the case can go no further. This pushes the bullet back into the case and retains its position and determines the (theoretical) maximum COAL, (more or less) to the rifling. You'll need a dial caliper, and it's best to repeat the measurement a few times to insure consistency in the average measurement. I also use this method to determine single-loading cartridge length (and throat deterioration) in my service rifle. 

IMHO there's quite a bit of variation in maximum COAL for the wide variety of 9 mm bullets and barrels. I only load 147 gr JHPs and Brazos 147 gr CRN bullets in 9 mm. For example, the approximate maximum COALs in my 1:10 twist Fusion 1911 barrel: 

147 gr Hornady XTP: 1.155"
147 gr Brazos CRN: 1.185"
147 Magnus JHP: 1.235" (beyond SAAMI length...well into 38 Super length territory)
147 Zero JHP: 1.230"                               (ditto)

Note that these measurements are ONLY valid for my barrel. 

For simplicity I load all three JHPs to ~1.100" and the XTP tend to be the most accurate. At this COAL the XTP also has the shortest jump to the rifling. I load the Brazos to 1.130". All feed and cycle properly using this method.

What brass? If you have a longer bearing surface and crush into the internal case taper, they will bulge. A softer bullet may simply collapse in.

John Dervis wrote:I bought some Brazos 9mm bullets and loaded them the same as I loaded some Acme coated bullets and had a similar problem. The Brazos bullet keeps its full diameter longer so the pointed area is thicker than the Acme bullet which caused my problem. I too had loaded up a bunch so my solution was to deepen the seating depth a little and run them all through the seating die again.  That solved my problem. 

Good luck.
John

Thanks John. I suspect this could have been the issue. I also switched out the old die set for a brand new die set. I had to purchase some used ones on ebay, because there is a 46 week lead time for 9mm die sets.

Greg Walloch wrote:Can you show us a loaded round?  I use that bullet in that barrel.  What kind of brass?  What’s your crimp?

Starline and Federal, crimp is 0.378"

I managed to get this correct. I suspect I needed new dies, previous ones were from ebay. I switched these out for new ones, no issues.. Do I need a little bit more crimp?



[ltr]https://ibb.co/QXYHcBQ[/ltr]

I use .377 with that bullet.

I had a similar problem when first started loading 9mm. Started with Brazos 125 LG bullets which shot very well. The next batch I ordered 125 NLG. When I ordered I saw their blog post about the difference so I knew ahead of time.
Loaded a dummy round and used my barrel for a plunk test. Seated a little deeper until it passed. Measured and took 2 or 3 thousandths off and set that as my OAL.
Those shoot just as well as the 125 LG bullets.

https://www.brazosprecision.com/Overall-Length-OAL_b_9.html

Darrell