So I just converted a P250 to .40 caliber but what I really want to do is put a 357 sig barrel in it.

From what I understand P320 Barrels are the same as the older P250s. I measured the P250 40 and it is 3.6". (actually 3" and 5/8s) then I go and look at Sig's offering for 'compact' 320's and they say 3.9"....

I guess my first question is how are barrels measured... is it total length or just the length of the rifled part?

also, where to find a p320 or p250 3.6" 357 sig barrel?

quote:

Originally posted by Blume9mm:
So I just converted a P250 to .40 caliber but what I really want to do is put a 357 sig barrel in it.

From what I understand P320 Barrels are the same as the older P250s. I measured the P250 40 and it is 3.6". (actually 3" and 5/8s) then I go and look at Sig's offering for 'compact' 320's and they say 3.9"....

I guess my first question is how are barrels measured... is it total length or just the length of the rifled part?

also, where to find a p320 or p250 3.6" 357 sig barrel?

The standard P320 Compact and Carry barrels are 3.9, Full size are 4.7 iirc, and SUBCOMPACT is 3.6.

This changes a little bit when you get into the XCompact and other offerings, then you get into the true 3.6" "Compact" barrel lengths.

I don't have an answer to your second part as I've never been in the market for a .357 barrel.

Here's what is confusing... I go on Sigs site and they say the Sig P320 compact barrel is 3.9" but the barrel on my Sig P320 compact is 3.6" front to back.

Oh and somebody somewhere here in the last week posted a link to a web site that has numerous Sig barrels... hopefully they will jump in and help me.

Okay, in the words of Miss Emily... "never mind.."

I was measuring wrong... the measurement it seems is from the end of the barrel to the foot of the rear not the back of the chamber. From a practical standpoint I understand but really should not barrel length be the length of the actual rifled part of the barrel and not even include the chamber?

quote:

Originally posted by Blume9mm:
From a practical standpoint I understand but really should not barrel length be the length of the actual rifled part of the barrel and not even include the chamber?

Usually rifle, shotgun, and semi-auto pistol barrels are measured from the breech face to the muzzle. Revolvers are measured from the forcing cone to the muzzle.

If you are looking for replacement barrels, I recommend you go by the nominal lengths that the factory specifies. For example, the barrel length of a P229 barrel in US specifications is 3.9 inches, and regardless of what measurement you came up with.

Another thing to consider about SIG pistol barrel lengths is that the Classic line series’ lengths were no doubt originally specified in Germany and in millimeters. The P229 barrel I measured was 97.6mm and the P226 barrel was 111.9mm. When converted to inches, that’s 3.84 and 4.41, respectively (rounded). Rounding is common when converting from metric to English measures that we use here. Further, why not 100 or at least 98mm and 115mm? That could be because of how the barrels were finished, just as 2×4 lumber here doesn’t actually measure 2 by 4 inches. If the Germans claimed, for example, that the P229 has a 100mm barrel, that would have been converted to 3.94 inches, and that could be why the P229 is claimed to have a 3.9 barrel when it should actually be listed, if we round to the nearest 0.1 inch, as 3.8".

And as for measuring only the actual rifled portion of the barrel, 1. it would be difficult*, and 2. it looks better to say a pistol has a 3.9 inch barrel rather than 3.1".

*Plus, where does the rifling start? Do we include the “leade”? How about the depth of the muzzle crown? Does that get subtracted from the nominal barrel length?

I don't understand the 1/10th of an inch measurement.... as in 3.9" when by my measurement it is very close to 3" and 7/8ths. None of my rulers have 10th of and inch increments on them....

I've ordered the standard 3.9" P320 barrel in .357sig and we'll just have to see if it will work in my converted P250... remember ... I took the firing module out of a P250 in .380 and installed it in the conversion for a 40 cal P250....
I picked up a Sig P250 in 9mm a few years back just out of a whim but ended up trading it for a Beretta 92c because I had put a laser on the P250 and the friend I traded with has rotator cup problems and it is hard for him to raise his arm high enough to actually use the iron sights to aim with. One more looooong double action trigger pul on these for sure.

quote:

Originally posted by Blume9mm:
None of my rulers have 10th of an inch increments on them....

Off the top of my head, I have at least five or six that have 1/10 inch markings. In fact, I have a tape measure with 1/10 of feet divisions.
(Some of us find it easier to think in decimal terms. Very frequently I just measure small values in millimeters and then convert them to inches—and in tenths. )

I bit the bullet and ordered a P320 compact barrel in 357 sig directly from Sig... found it on another site but was only going to save $5 and I suspect they would have charged me shipping...

took only two days to get to me and so I've installed it and it seems to fit fine and function... this is just cycling snap caps.... will probably be a week or more before I can actually pull the trigger and see how the pistol does in both 357 and 40 cal ammo.

On a side note, because it ain't worth a separate thread: While at the on line Sig store I was looking to see if there was anything else I had to have.... found this old fashion glass and the most amazing thing is it is actually made in America!