.40 long for G20 with .40 S&W barrel?

[BlueOvalBruin]

I’m new to Limited and have a few questions about ammo. What are the main reasons people load .40 long? If a gun is able to reliably cycle .40 long (1.180-1.200” OAL) and .40 regular (1.125” OAL), what would be the advantages and disadvantages of both? I will be putting a lone wolf .40 S&W barrel in a Glock 20 slide and can put any kind of ammo I want through it since it will cycle anything pretty much. If I should load .40 long I can send lone wolf some dummy loads and have them cut extra freebore to fit my handloads.

Here’s what I’ve been able to come up with so far.

.40 long OAL:

Advantages:

1. Possibly improved feeding

2. Lower pressures to make major

3. Rounds probably seat better in magazine

4. ?

Disadvantages:

1. More powder to make major

2. Secondary process required for cutting freebore

3. Can’t run ammo through my G35

4. ?

.40 w/ regular OAL:

Advantages:

1. Less powder to make major

2. Less freebore might mean better accuracy with regular length or factory ammo

3. Ammo interchangeable with G35

4. ?

Disadvantages:

1. Higher pressures to make major (could result in leading with moly-coated lead bullets)

2. Rounds looser in mag (don’t know if this is a problem or not)

3. ?

[Braxton1]

One of my SWAT guys carries a G-20. As you know, full-power 10mm ammo is hard-to-find. So he just loads regular Winchester White Box 40s in the mag and lets fly (for practice only; carries Norma full-power for duty use).

The only thing that we found, besides 100% reliability so far, is that you need to clean the heck out of the chamber before switching back to 10, as a carbon ring will develop in the chamber that is not "occupied" by the shorter length of the 40.

Glock has reported some gas-cutting in the chambers, but we haven't seen it yet.

[Flexmoney]

Glock has reported some gas-cutting in the chambers, but we haven't seen it yet.

Hmmm...scare tactics on their part?

[Flexmoney]

B-O-B,

You seem to have the aspects down pretty good.

If you are shooting a G35 also, then ammo sharing would be my #1 priority.

[Joe4d]

Loading long is dont for two reasons, 1911/2011 pattern guns and mags are easier to tune to run long loaded 40 reliably,

and super fast burning powders need the extra room to make major without pressure problems. If your gun runs on standard OAL, and you have another gun that only feed standard OAL, and you stick with published load data, there is no reason I can think of for you to worry about it.

[barney88pdc]

One of my SWAT guys carries a G-20. As you know, full-power 10mm ammo is hard-to-find. So he just loads regular Winchester White Box 40s in the mag and lets fly (for practice only; carries Norma full-power for duty use).

The only thing that we found, besides 100% reliability so far, is that you need to clean the heck out of the chamber before switching back to 10, as a carbon ring will develop in the chamber that is not "occupied" by the shorter length of the 40.

Glock has reported some gas-cutting in the chambers, but we haven't seen it yet.

I am sure you are correct and I have heard of other people doing the same thing. I just do not understand how the striker would hit the primer. The 40 S&W case being shorter is seems like the round would go deeper in the chamber and not allow the striker to hit it? I guess if the extractor caught the case and held it "proud" of the bottom of the chamber it would fire. I just bought a DW CBOB in 10mm and I dropped a 40 S&W case in the chamber just to see and it defenately sit deeper than the 10mm. I did not try to fire it nor would I but it seems like bad ju ju?

Edited December 23, 2009 by barney88pdc

[Flexmoney]

Seems that most guns that locate the round off the case mouth...really have their rounds held by the extractor.

I tell this story often when this comes up (I should go check my details, as I haven't told it in a while)...

When I made GM in Limited with a Glock, there were about 6 or so others that I knew of* that had done the same thing. Three of them were shooting the G20...and they all talked of shooting plenty of 40 through the 10mm barrel.

I've never done it, so I can't say. My girlfriend shoots our G20 and I just went ahead and put a 40 chambered barrel in it because she was going to be the one shooting it.

(* I later learned that there were a couple of Limited GM's in Texas that shot Glocks.)

[RufDog]

I've shot a my fair share of 40 through a Delta Elite. I have never heard of any bad things about doing this except for the carbon ring as mentioned. Like Flexible Money stated concerning the extractor, you could have a reliability issue if the rim were to get ahead of the extractor.

[BlueOvalBruin]

If a .40S&W round could fire in a 10mm chamber without much issue (other than carbon ring) I suppose a .40 round loaded to normal OAL would have no issues firing in a chamber that’s been throated for .40 Long. Is that assumption correct? Maybe the best of both worlds would be to have lone wolf cut more freebore for .40 long and then have the flexibility of being able to shoot either long or normal if I change my mind in the future. Lone Wolf doesn’t charge for chamber mods so it wouldn’t cost me anymore.

[Flexmoney]

Read this first. I think Clay did some good work here.

http://montac.net/glock/bullet%20jump/bulletjump_1.htm

I'd probably just shoot the 10mm stock barrel if I wanted to go long.

[Duane Thomas]

2. Lower pressures to make major

Actually whether the round is loaded long or not, it requires the same chamber pressure to drive the bullet to the same velocity. What long loading does is allow you to achieve that pressure with a considerably longer pressure spike.

[Chuck Merriam]

I read that article once about the free bore of the stock glock barrels. If I remember the stock 40 barrel will take quite a long load...however the mag is the limiting factor on length. The article was more about it's effect on accuracy as far a bullet jump to the rifling. I have to agree the 40 barrel would be my choice. I just caught the fact you said G20 Slide....how about the frame? If you don't use a G20 frame then you will be limited by the G35 mags to about OAL of 1.15". Honestly being new to Limited, I would stick to the G35. I and many others here have spent way too much money learning lessons we could have avoided by just asking. Practice and enjoy... become one with the gun...trust me you will be better off. I think Glocks are a great bang for the buck..but I have seen way too many franken guns have problems. Watch Dave Sevigny shoot his (if you can in person) you will understand how good a near stock one can be. If you really want to make the G35 better, get a fantastic trigger job.

[rjkelso]

Does a longer pressure spike mean a smoother feel? A shorter pressure spike being sharper?

[BlueOvalBruin]

Chuck,

I will be using a large frame from a G21SF but will be putting a Lone Wolf G20L (6”) slide on it with a .40 S&W barrel. I found a good deal on a used G21SF and figured I could use the stock slide in IDPA CDP division and the lone wolf slide in Limited. I like my G35, but I have large hands and the small frame glocks chew up my hands. I’ve tried some of the remedies (glocktail etc.) but I haven’t been very fond of them. I haven’t been getting slide bite from the G21SF and it fits my hands a bit better. Shooting the G21SF the last few weeks has shown me how much I really appreciate the longer sight radius of the G35 though. My shot calling is much more accurate with the longer slide. Anyway, we’ll see how everything goes. It will probably be a little while before I get everything setup.

Flex,

I read through that link you posted and there was a lot of good info, thanks. I found it interesting that there was so much freebore in the stock and aftermarket barrels. I have had to have my lone wolf barrels recut in the past because of interference with the moly-coated bullets (which can have an OD of .402”). I suppose the freebore depth would not need to be cut then assuming the lone wolf barrels are cut like the KKMs.

[G-ManBart]

Loading long is dont for two reasons, 1911/2011 pattern guns and mags are easier to tune to run long loaded 40 reliably,

and super fast burning powders need the extra room to make major without pressure problems. If your gun runs on standard OAL, and you have another gun that only feed standard OAL, and you stick with published load data, there is no reason I can think of for you to worry about it.

Not really.

Pressure is pressure. The powder needs to produce X amount of pressure to produce Y amount of velocity with a given bullet. Having more or less case capacity won't change the amount of pressure needed to get that velocity. Going to a larger case, with more case capacity, just means you'll need more of that powder to get the required pressure, which hasn't changed. R,

[mhs]

Actually whether the round is loaded long or not, it requires the same chamber pressure to drive the bullet to the same velocity. What long loading does is allow you to achieve that pressure with a considerably longer pressure spike.

Are you sure about this? I agree that a longer peak pressure can be acheived with greater case volume, but I thought that since the peak pressure is pushing against the bullet for a longer time you would get higher velocities than the same pressure in a smaller volume, or the same velocities with a lower pressure. Wow, long sentence.

[BlueOvalBruin]

Actually whether the round is loaded long or not, it requires the same chamber pressure to drive the bullet to the same velocity. What long loading does is allow you to achieve that pressure with a considerably longer pressure spike.

Are you sure about this? I agree that a longer peak pressure can be acheived with greater case volume, but I thought that since the peak pressure is pushing against the bullet for a longer time you would get higher velocities than the same pressure in a smaller volume, or the same velocities with a lower pressure. Wow, long sentence.

That is my understanding. For a given load velocity, loading to a longer OAL will reduce the peak pressure but the effective pressure pulse will last longer. I just worry about using fast powders like Solo1000 (which I have plenty of) with a 180gr bear creek bullet which is a pretty long bullet. I suppose having the extra wall thickness of the large frame barrel will help give me a little cushion, but there’s still some risk.

[Flexmoney]

I will be using a large frame from a G21SF but will be putting a Lone Wolf G20L (6”) slide on it with a .40 S&W barrel.

They likely aren't (yet) legal for the sport...except in Open division.

There is no gun produced that is a Glock 20/21 with a 6in slide. To get there using various "components" the rules for Limited and L-10 state that:

Any complete handgun or components with a minimum production of 500

units by a factory and available to the general public.

We have a thread around here talking on that some. (it would be a fine choice, but it seems that LW and USPSA's NROI aren't working with each other to make it happen)

[BlueOvalBruin]

Lone Wolf said they are close to the 500 mark for the 6" G20L slides so it should be legal in Limited/L10 fairly soon. The frame is definitely good to go now and we're just waiting on the slide now. Even if it takes a while it's no big deal since I won't likely be shooting any majors in Limited for a while (prob over a year). It's mostly for 3gun (since no production division) and local non-uspsa matches for now.

[BlueOvalBruin]

An update:

I have been shooting my 6” G20 since Feb and have settled on a great load. I am using 4.7gr Solo1000 under a 180gr Bear Creek moly coated bullet at 1.185” OAL with federal SPPs. The load gets 175PF, but it’s a heavy slide so it needs the extra push to liven it up. The barrel is throated for moly bullets out to 1.200” OAL by the way. This load has zero leading of any sort which was not the case with my shorter 1.135” major load.