.357 plated bullets in 9mm gun - how tight is too tight?

[IMtheNRA]

I slugged some of my 9mm barrels, and they're about .356

It is hard to be sure because I am using calipers to measure the rough looking lead sinker after I pounded it through the barrel, but I think .356 is pretty close.

These Berry's double struck plated 125 grain HP bullets are consistently .357

So I'm wondering... How much room for measuring error do I have if I want to shoot a few test rounds in my 9mm Glocks, Berettas, and Hi Powers? What if the barrels are actually .355 and I try to stuff a .357 bullet in them?

 

[Walkalong]

I haven't slugged my 9MMs, but I have tried some Powerbond 125 Gr .3575/.358 bullets in them. Shot just fine. Now I know I can if the need should ariise.

4.9 Grs of SR4756 & a WSP primer @ 1.050 (+/- .002/.003) gave me:

Hi=1072
Lo=997
Avg=1050
ES=75
SD=29.

 

[IMtheNRA]

Thanks, Walkalong! Say, do those SD and ES numbers look somewhat on the large side?

 

[jwrowland77]

If you slugged your barrels and they're .356, then the .357 plated should work just fine.

My 9mm slugs at .3555, and I size my cast boolits to .357. I actually get better accuracy from them.


Sent from my iPhone using Tapatalk

 

[IMtheNRA]

I was worried in case my barrels are actually .355

In any case, I'm going to load a few test rounds and take them to the range tonight. Going to use a Beretta 92 Elite-I. The dummy rounds already passed the plunk test.

 

[Walkalong]

do those SD and ES numbers look somewhat on the large side?

Yes, but SR4756 is like that, until pressure gets up there. It's pretty good then, in small cases. Or at least cases where fill is near 100% and the pressure is up there.

It's horribly position sensitive in a big .38 Spl case with a light plinking load. ES in the hundreds.

 

[eldon519]

Using an oversized bullet (within reason) may increase chamber pressures, so just make sure you work up from starting loads rather then just trying to substitute it into a near max or max pet load. I think you will be fine.

 

[ny32182]

I shot about 10k .357" plated bullets through a Tanfo stock 2, and the only difference I could see is that they used about a tenth of a grain less powder to get the same velocity as a 356".

 

[longdayjake]

All I shoot through my M&P pro performance center is .357 147 grain bullets. I was amazed at how much of a better shooter I am when I use properly sized bullets for my guns.

 

[cali_blues]

All I shoot through my M&P pro performance center is .357 147 grain bullets. I was amazed at how much of a better shooter I am when I use properly sized bullets for my guns.

Do you sell those?

 

[ants]

IM the NRA (I like that name)

Many of us have done it, so here's the bottom line as I know it:

As far as fit in the bore and pressure, Plated bullets act like lead bullets. .357" is just fine.
Best to use lead bullet data, those Berry's will obdurate like lead and all will be fine.


However...

You asked how tight is too tight, and the real test is fitting the chamber.
Thinking through it step by step:

If the chamber is at SAAMI minimum .3810" at the headspace step
and you use .357" bullets then your maximum case wall at case mouth
is 0.012" (two case walls at 0.012" equals 0.024" plus 0.357" equals 0.3810").
That should work for virtually all 9mm Luger brass we normally encounter.
If any brass is thicker than that, your cartridge won't even chamber, it will be too fat.
This of course assumes the bullets are no larger than 0.357". Measure them upon delivery.

So the final test is actually chamber fit, not bore fit. .357" in a .356" bore is perfect.

The only way to check is to load and try the fit in the chamber. It should work,
but load 5 and try them first. Shoot to make sure they feed from magazine to chamber,
and go fully into battery and fire.

Chances are nearly 100% that it works, it certainly works in all my guns and
most guns.

 

[IMtheNRA]

Thanks a lot, Ants!

While I did not measure the girth of the finished rounds, I measured at the case mouth and they were consistently 0.377 without even applying the crimping die. Then, I did the barrel plunk test and they passed at 1.080, but did not pass if I made them any longer than 1.085 It seems the bullet ogive was contacting the rifling at 1.085

However, while shooting the small lot of test rounds, I noticed that on the first round, when I released the slide, the Beretta did not make it's usual metallic "snick!" sound. I suspected the feed angle and the the long bullet profile of Berry's 125-gr plated hollow point bullets were not perfectly compatible. I theorized that due to clumsy feeding, the slide encountered resistance when it was going into battery.

Today, I made another test lot of this ammo, and I reduced the length to 1.050 To my relief, the "snick!" sound returned.

I'll shoot over the chrono tomorrow.