Correct bullet size for 38 Supercomp

[Jadeslade]

Are these the correct size for loading 38 Supercomp? These are Zeros from Rozedist. I have been buying Atlanta Arms and Ammo. Thanks.

38 Super (.356 Diameter) - 125 GR JHP

[Ray_Z]

modern open guns start life with a 9mm barrel that has been chambered for super comp. So the answer is .355. But if you're not sure, slug your barrel. The true 38 super is .356 but that's an old caliber in an old gun. And major loaded ammo should never be shot in it.

[Jadeslade]

This is in my Infinity with a Schuemann 38 Super Hybrid Barrel- it's about 3-4years old. The AAA bullets are 125gr-not sure of manufacturer-maybe Hornady. Thanks. So this sounds like I should be using the .355 size?

[Sean Gaines]

shoot 9mm .355 gr bullets, unless otherwise noted by a gunsmith, most of the barrels are chambered in .355 diameter

[G-ManBart]

This is in my Infinity with a Schuemann 38 Super Hybrid Barrel- it's about 3-4years old. The AAA bullets are 125gr-not sure of manufacturer-maybe Hornady. Thanks. So this sounds like I should be using the .355 size?

The bore on your barrel is almost certainly .355" so .355" bullets will work and should give decent accuracy. You can use .356" bullets with no problems and possibly slightly better accuracy. From the Schuemann website:

(8) Barrel Groove, Land, and Recommended Bullet Diameter

Barrels will have the following groove and land diameters. For optimum accuracy, lead

bullets should be 0.002 or 0.003 inch larger than groove diameter; copper jacketed bullets

should be 0.001 or 0.002 inch larger than groove diameter.

.355 caliber: groove diameter = 0.3550 inch, land diameter = 0.3460 inch.

[G-ManBart]

modern open guns start life with a 9mm barrel that has been chambered for super comp. So the answer is .355. But if you're not sure, slug your barrel. The true 38 super is .356 but that's an old caliber in an old gun. And major loaded ammo should never be shot in it.

Not necessarily, and not necessarily. There is factory .38 Super ammo that makes Major (just barely) that stays within SAAMI pressure limits that would be safe in any factory .38 Super...even an old Colt from the 30s so long as it's in good shape. There isn't much reason to do so, but it wouldn't be unsafe.

There are also brand new guns in .38 Super with .356" barrels and you can shoot Major ammo in them just fine. There are plenty of older Super aftermarket barrels still out there with .356" barrels that you can shoot Major in just fine as well. When I got my first Open gun the barrel companies weren't making Super barrels with .355" bores and the power factor was higher back then (I got mine around 1991). The switch to .355" for both Super, Supercomp and 9 is relatively recent. R,

[XRe]

The true 38 super is .356 but that's an old caliber in an old gun. And major loaded ammo should never be shot in it.

Bull puckey.

.356 bullets are all I drive in mine. Hell, Angus drives (or drove) .356 125gr JHPs in his 9mm... My current gun shoots both of them quite accurately, as have previous guns...

Try both. The larger bullet will tend to seal tighter, and one or the other may give you better accuracy. The .356 bullet will tend to generate higher pressure, though, so you'll need less powder to make major - that may or may not be a good thing in your config.

[CocoBolo]

Well did the chicken or the egg come first. The real answer is that you can use either, and I think XRE and G-Man agree on that and those are two of the smartest guys I know when it comes to Open guns. Which one gives the best results is purly a matter of trial and error.

I shoot .355 in both of my 38 Super Comps and I have shot .356 in them when that was all I could get.

When loading and especially up there over the top of the charts one needs to exercise due dillegence in checking for pressure signs when working up a load. Start with the lower charged rounds and when you get to either pressure signs or your pf STOP.

[Jadeslade]

Thanks. I'm waiting for a thousand .356 Zero JHP 125gr-I'll give them a try. Thanks

[GrumpyOne]

I've shot both .355 and .356 with no ill effects. I believe Corbon is the ammo G-man is talking about.

[usmc1974]

I called Serria bullets and talked to the tech's they said .355 for both 9mm and 38 super. Now .356 will work in both but the .356 cause higher pressures using jacketed bullets. I use .355 in both 9mm and 38super now I do have a 1000 lead 147 9mm rounds to shoot and about 1500 135 FMJ .356 9mm's but all down loaded to a PF of about 140.

[Pezco]

It depends on your barrel, but like most have said .355 is what I'm using.

[RH45]

I not only run that same Zero, 125 grain, .356, jhp in my .38 Supercomp, but, I run them in all my 9mms too.

I've found them to be more accurate in most of my pistols. The only exception is my M&P Pro, which seems to be slightly more accurate with Hornady 124 grain, .355, XTP bullets.

[GrumpyOne]

I not only run that same Zero, 125 grain, .356, jhp in my .38 Supercomp, but, I run them in all my 9mms too.

I've found them to be more accurate in most of my pistols. The only exception is my M&P Pro, which seems to be slightly more accurate with Hornady 124 grain, .355, XTP bullets.

I like the XTP's as well, but boy are they expensive!

[Jadeslade]

Less than AAA ammo!

[GrumpyOne]

Less than AAA ammo!

I don't know about that! Last XTP's I bought were $26.95 PER HUNDRED! I was just starting to load 38 super and needed them for a test while waiting for my MG's to arrive.

[Jadeslade]

Wow!

[RH45]

Less than AAA ammo!

I don't know about that! Last XTP's I bought were $26.95 PER HUNDRED! I was just starting to load 38 super and needed them for a test while waiting for my MG's to arrive.

I'd read that they were the most accurate bullet available, and was at a local gun shop last fall, and they had 3 boxes of the 9mm, 124 grain for about $15 each, so I picked them up to give them a try, but, at about twice the cost of Zeros, and only showing that they were slightly more accurate in only one of my pistols, I'll keep using Zeros---if I can get them!

[GrumpyOne]

Less than AAA ammo!

I don't know about that! Last XTP's I bought were $26.95 PER HUNDRED! I was just starting to load 38 super and needed them for a test while waiting for my MG's to arrive.

I'd read that they were the most accurate bullet available, and was at a local gun shop last fall, and they had 3 boxes of the 9mm, 124 grain for about $15 each, so I picked them up to give them a try, but, at about twice the cost of Zeros, and only showing that they were slightly more accurate in only one of my pistols, I'll keep using Zeros---if I can get them!

Oh, they shot really well! But the price was killing me. I've still got the empty box around here somewhere with the price tag on it (may post a pic of it!). They were bought from the local gun shop, which generally has to make 50% on everything the sell so....But when you need 'em, you need 'em! Like I said, I was developing a load and waiting for my MG's.

Edited February 25, 2010 by GrumpyOne

[Ray_Z]

The true 38 super is .356 but that's an old caliber in an old gun. And major loaded ammo should never be shot in it.

Bull puckey.

.356 bullets are all I drive in mine. Hell, Angus drives (or drove) .356 125gr JHPs in his 9mm... My current gun shoots both of them quite accurately, as have previous guns...

Try both. The larger bullet will tend to seal tighter, and one or the other may give you better accuracy. The .356 bullet will tend to generate higher pressure, though, so you'll need less powder to make major - that may or may not be a good thing in your config.

I was going by what my gunsmith and many of the other open shooters told me. That Schumann (I think I spelled that right) barrels are all .355 and have to be chambered for the cartridge and the extractor tuned for the case. If I were to go to a .356 bullet I'd have to start over from scratch on building my load for it. I sure wouldn't want to shoot 9.1 of 3n37 behind a 115gr mg hp if it were .356

[XRe]

I was going by what my gunsmith and many of the other open shooters told me. That Schumann (I think I spelled that right) barrels are all .355 and have to be chambered for the cartridge and the extractor tuned for the case. If I were to go to a .356 bullet I'd have to start over from scratch on building my load for it. I sure wouldn't want to shoot 9.1 of 3n37 behind a 115gr mg hp if it were .356

All you'd have to do is drop your charge a few tenths and work it back up. You'd likely end up 2-4 tenths lower on the load. That's it.

It is true that you'd not want to shoot major PF ammo in an unsupported chamber .38 Super - but that's because the case could potentially blow out in the unsupported area (resulting in the phenomenon known as "Super Face"). That's not because you can't run major PF ammo in a .356" barrel.

Most barrels that most of us are running are nominally .355" barrels, and they can run .355, .3555, and .356 bullets just fine. There will be pressure differences with each - but more importantly, there may be accuracy differences, depending on the barrel. Or not. My current barrel runs .355 Montana Golds and .356 Zeros with equally impressive accuracy (see my thread on my Brazos Pro Sx in the Gallery forum.... the group I shot was Zeros, the group Bob shot was Montana Gold).