Need some quick info, 40SW barrel diameter

[armoredman]

I slugged a 40 SW pistol bore, came up with .402. Factory bullets are .400/.399, on the few I've looked at. Factory bullets gave unimpressive accuracy. Cast bullets sized industry standard at.401 gave mediocre accuracy and bad leading. Oversize cast bullets sized at .404 gave excellent accuracy and minimal to no leading.
Question, to 40SW owners who have slugged their bores, it this the same diameter you have come up with, groove to groove? Groove depth is approx .003, so a .400 bullet has .001 to engage the rifling, not counting obturation, which I would have to assume is minimal with a jacketed projectile.
The factory representative refused to give me the information over the phone, wouldn't even say whether or not such a diameter is within factory specs,:banghead: so I ask you, the experienced casters and re loaders, is this a normal diameter? Not mentioning the manufacturer until I get some good info on whether I am wrong or right, and I've been wrong more than once before.

 

[LiveLife]

Although .400" should be the groove diameter of 40S&W barrels, Many post factory barrels to be oversized by .001"-.002"+. In fact, Lyman #49 reloading handbook indicates they used .401" groove diameter test barrel fixture with .400" jacketed and .401" lead bullets. I have long wondered about the discrepency between Lyman and Hodgdon load data where Lyman load data for 40S&W was much higher.

Also, depending on the manufacturer and QC used, you may end up with variations in finished products' dimensions (it does happen, just read some 1911/polymer threads on "Auto loader" category for some "OMG, really?" stories. On a recent thread, Ruger sent out a finished pistol with a smooth bored barrel that wasn't rifled.

So, depending on the manufacturer and product line, groove diameter of .402" may not be the exception. Personally, I prefer to shoot .401" factory barrels and .400" even better.

 

[armoredman]

I was wondering this fact...the factory rep wouldn't give me the factory dimensions for the barrel, but did offer to "look at it" being sent in on my dime, and if they thought it was OK I'd be charged $70 plus shipping both ways, about $200 total. New barrel is $289. Pistol cost me $365 plus tax. New gun is $550 MSRP.
So I figured I'd ask here. Thank you for your response, I appreciate it.
Anyone else have any info?

 

[popper]

What is unimpressive or mediocre accuracy? How much leading? What does it do with WWB ammo @ 25 yds? What do you expect? It's not a target pistol, but should do 3" @ 25. Go ahead and name the brand without flaming them. If you don't state details, you get little help.

 

[918v]

Lasercast sizes their bullets to .403" so it looks like a match made in heaven.

To answer your question, the poor quality of guns today is inexcusable.

 

[918v]

How much leading?

Any leading is unacceptable.

 

[armoredman]

Leading with standard sized .401 is excessive, compared to leading I have with CZ barrels with the same lead mix/lube. Leading with .404 sized is minimal to non existant at this time.

This is .401 sized, and this is actually one of the best targets from that day, most were far worse.



This is afterwards. .404 sized, and all targets pretty much looked the same.



What's odd is this green B-27 was shot with factory Federal 180 grain FMJ, very first 5 rounds at 25 yards, very nice group.



The next group was thrown 8 inches below that, same POA, several inches wider. I couldn't get a repeatable POI. The 135 gr HydraShoks were giving WIDE groups, but I put that down to perhaps this gun doesn't like 135 grain bullets. Full disclosure, I was shooting from a standing position, and the Beretta Storm trigger is VERY mushy, (whoops, guess I said the name), and spongy with the lifting of that long firing pin block that pops out of the top of the slide.

Popper, I refuse to use WWB - that's just about the worst factory ammo on the market today, with the exception of AMERC. WWB is good for one thing - making reloadable brass.

918v, that's very cool, thanks for the info - I cast my own in the garage.

Now that I have a load that should work well, with those wider slugs, I will experiment if this helps for the 25 yard repeatable accuracy.

 

[918v]

Beretta likes to make oversized bores. My M9s were .358" and had .360" throats. I would shoot .359" .38/357 bullets with no leading. The chrome lined bore helped too.

 

[LiveLife]

armoredman, so it was Beretta Storm? What model (full-size, compact)?

 

[armoredman]

Beretta PX4 Storm full size.

 

[popper]

Just like mine. Guess I'll have fun casting for it. Smaller chamber than my XDm but I haven't checked the bore. It didn't do too well with raineir plated 165 either, the XD likes everything so far. I like the feel, my trigger is fine but the speed loader is junk. I think my 165 mould as cast is .404 but I don't know if it will fit the chamber. Oh well.