mystery eBay barrel (XD-40 9mm conversion)

I took a chance and I think it paid off. {spoiler: it did pay off}

9mm conversions for the XD-40

The Springfield Armory original¹ XD 9mm, .357 SIG, and .40 S&W use the same frame. The latter two can be converted to 9mm with either

• a conversion barrel
• a complete 9mm barrel and slide assembly

The slide assembly route is about the same cost as a whole 9mm so the conversion barrel is preferable. No one except one high-end shop still make barrels for the original model. There are a few on the used market, and still fewer in the 5”² flavor.

the listing

I saw this listing for a barrel: Storm Lake Springfield XD Tactical 9mm Pistol 5 3/8" Barrel, so I investigated.

The label on the barrel’s packing sleeve reference a custom order for a customer – I have blurred his name for privacy. It gives various internal data like inventory location (don’t care) and model (I care a lot).

The model was listed as XDT9 Conv DI. This seemed to suggest a 9mm conversion barrel for the tactical (5 inch) line. The 9mm has no conversion options because the larger caliber barrels won’t fit in the 9mm slide. So if conv really does mean conversion it has to denote conversion to 9mm. Not sure about the DI. It might mean drop-in which was common language when the conversion barrel was new.³

OAL is given as 5.51”. I think this was so barrels for the 5” guns could have porting or a thread adapter on the end. Or have the last half-inch lopped off if desired. Looking at the pics the barrel’s diameter seemed to be greater than that of the stock 9mm, which would make sense for a conversion barrel to fit a .40 slide. The sleeve label notes No Ports.

With the label out of the way we can see some clues on the barrel itself. It’s stamped STORM LAKE XD 9MM but lacks the Storm Lake logo I’ve seen on others. Maybe no logo on the custom jobs? The overall shape of the breech end in the listing pics matches the shape of my stock .40 barrel.

All these clues suggested this was a conversion barrel that might fit my XD. I was the only bidder at the starting price (~$130) and won it.

the fitment

I received the barrel and it was in great shape. I dropped a 9mm round in and it plunked as it should. So far so good. I removed the round and cleaned and lightly re-oiled the new-to-me barrel. Patches run through were barely smudged.

I field stripped the XD and cleaned it up too before dropping in the new barrel. It fit nicely. The recoil spring installed as expected so I reassembled the XD and did a function check; seems to work. 9mm mags are recommended for reliability but I just ordered a used one so it’ll be a week until it gets here. So I loaded the 9mm round in the .40 mag – it fed and extracted correctly when I cycled the slide. Obviously I won’t know for sure until I fire it but it looks promising.

If it works with the 9mm barrel I’ll pick up another 9mm mag or two. If it doesn’t work I’ll relist on eBay and someone more clueful can try it in their XD. Will update this space after a range test.

If it’s not obvious, the longer white one is the 9mm conversion barrel. It weights 143g. The shorter black “Melonite” one is the OEM .40 S&W barrel, 119g. The conversion barrel is heavier because of the 0.5” increased length and because the walls of the barrel are thicker. The outer diameter of barrel has to be the same to fit the .40 slide but the 9mm bore is smaller. Hence thicker walls. Quick math suggests the conversion barrel’s wall is 0.0225in (0.5715mm) thicker.

update: testing the conversion barrel

what worked

I ran a mag of 115gr Herters FMJ through it; all fed and fired correctly. Felt great and no squirrelly behavior.

They averaged 1209fps for (373ft-lbs). The box says 1190fps. If that’s for 5” then 5.5” averaging 1209fps makes sense.

what didn’t work

There were 3 stovepipes. I have no experience in this matter but I suspect it’s a function of one or more of these:

• the heavier barrel
• the lesser power of 9mm
• extractor? This thread discusses shaving the extractor to make contact with 9mm cases more positive.

This thread on a Glock forum suggests that return springs and light projectile weights can both be problematic.

I’ll try 147gr white box rounds next time I go out to see if that helps. I wouldn’t think a magazine could cause stovepipes but I’ll also test with the 9mm mag when it comes in. If that doesn’t work I’ll try to load some hotter 9mm. If that doesn’t work I might try dropping in a 14lb⁴ recoil spring.

Last round slide hold-open did not occur. This is fairly common with conversion barrels, or it might just mean the slide isn’t able to travel far enough back.

update with heavier projectiles

I retested with 5 mags of heavier rounds today:

• 147gr book max
• 147gr just under book max
• 124gr book max
• 124gr just under book max
• 147gr retail Federal AE FMJ FP

Every round extracted correctly. Last round slide hold-open generally didn’t work. Sometimes it locked back on the 9th round instead. Magazine issue? Will retry with the 9mm mag.

I’ll still pick up a lighter spring to see if I can get 115gr to behave.

Update: next-to-last hold open is definitely a mag issue. See this archived pic.

corrosion on Berry’s

When I opened the box of Berry’s 124gr I saw that a few had green corrosion on them. I did some googling and saw that it’s associated with moisture. I seem to remember a few months ago I spilled some water in the box but didn’t think anything of it. Lesson learned.

I put the affected bullets in the ultrasonic cleaner for a few minutes and it took the green right off. The patches where the corrosion was are not as shiny as the rest of the projectiles but no lead is showing. I used the phone’s enhancement function to make the damage easier to see. I dried them completely then put them in a baggie back in the box. I’ll use them first just in case.

effect on velocity

I’d given my full-frame 9mm to my daughter earlier so the only 9mm sidearms I had were subcompacts with 3.1” and 3.2” barrels. Plinking rounds (Berry’s plated RN 124gr) are ~952fps through the sub guns and should be ~1075fps out of the 5.5” barrel.⁵ 124gr Gold Dots are moving 1013fps out of the mouseguns and should be ~1125fps out of the 5.5”.

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Srsly: do not take my word (or anyone else’s) on matters of reloading. Get some manuals, start with light charges and work up, etc. You are responsible for your own loads as I am mine.

Also see the BSK reloading calculator announced in this reddit thread.

1. there was XD, then XD mods 2-4. But we can call the original one mod 1 for clarity. ↩

2. the so-called tactical model ↩

3. The two major type of aftermarket barrels are “drop-in” and partial fit, the latter requiring final fitting by a gunsmith to the specific sidearm. ↩

4. the stock spring appears to be 17lbs according to Wolff. And springs are their business so they should know. ↩

5. these are loaded so they do not exceed the 1250fps limit out of the 16.5” carbine. ↩