You know, I'm not sure I like the looks of that 147 Gold Dot.
On the other hand, the 135 Gold Dot looks GREAT. The photos Speer has published of expanded rounds in denim-covered gel and a 2" barrel not only look good, it's clear the hollowpoint cavity hasn't yet "bottomed out", so they're good for at least another 100 - 150fps and probably 200 no sweat. Which means they'll be just fine in 4" tubes and I'm 90% sure they'll hold together and maintain expansion in 6" tubes. What else...Speer claims this new 135 is good at not getting "jerked out of the shells on recoil" (aka "jumping crimp") in superlight guns, so this could be THE answer the Scandium/Titanium/Aluminum crowd has been looking for.
Other choices:
* The Remington and Winchester 158grain lead hollowpoint in 38+P are more or less the same load...the Remmie is maybe a hair faster. They'll expand at around 825fps, do about 850 from a 2" tube and about 900 from a 4". These old classics just work, period. A great choice in cold weather where a deep punch past heavy clothes is required. Even when they fail to expand, the "semi-wadcutter profile" with it's flat nose has more wounding on tap than the basically round-nose profile of some of these others. (You'll hear of some people recommending this same basic load but without the hollowpoint cavity, called a "Keith profile", and with some merit.)
* Bufallo Bore is about to ship a supercharged version of the above - same basic slug but doing 1,000fps from a 2" so figure 1,050 - 1,100 from a 4". This is MAJOR energy levels, over 350ft/lbs, into the low end of 357 power levels but they're claiming no extreme pressures due to careful modern powder choices. Still, I wouldn't use these in a marginal gun...late model K-Frame 38, any 38spl variant Ruger Service/Security Six series, 38spl SP101, late-model J-Frame 38 would be fine. A few others mebbe...not THAT many others though. Not my own Charter Arms Undercover fr'instance.
* Cor-Bon has a new 100grain Pow'R'Ball in 38Spl. From a 4" barrel it oughta get a good head of steam up. I don't like how light Cor-Bon went on this load but the advantage is that the design can't "clog". Hollowpoint cavities can fill with clothes...which can retard or eliminate expansion. Cor-Bon got the bright idea of shoving a rubber ball in the cavity, "clogging it" from the get-go. The ball is shoved deeper in, begins the otherwise normal JHP expansion process, then falls away once the lead/copper has "gone fat enough". Peak expansion then matches typical hollowpoints of convensional type. Upshot: a clogproof JHP.
* Winchester's 130grain Supreme +P is a JHP with a really, REALLY big hollowpoint cavity. It works well enough in 2" tubes, should be just fine in a 4". This round really started the "huge hollowpoint specially for 38Spls" trend that the Gold Dot 135 seems to have copied...arguably better, but this Winnie ain't bad either.
* Speer's 125grain +P worked OK too, in 2" and esp. 4" barrels. The 135 will probably be better but if you can't get 'em...OH, and Bufallo Bore is about to load this older projectile at wild-child speeds...in a really good 38 gun, that might have merit.
Speer tends to sell their projectiles as components. Georgia Arms, Proload, Black Hills, Bufallo Bore and others are "Gold Dot houses" of good repute. So far, they don't have access to the newest 135 in VERY high demand but that will eventually change. Georgia Arms in particular has really good deals on 100-count batches.
Bufallo Bore's pair of super-hot 38Spls won't be shipping for another couple of months. We can bet those will be damned good loads though...both projectiles are well-known, well-documented beasties so if they get up the kind of speeds they're predicting...OH ya. In good guns, anyways.
The Cor-Bon Pow'R'Ball 100 is the "wildcard" in the deck...it could be really good, or it could be a stinker. Independent test data eagerly awaited.
Gold Dot bullets always have relatively thin jackets that are electro-plate bonded to the lead. This helps them expand at lower speeds, yet with the lead hard-stuck to the jacket they resist "overspeed shredding of the nosecone". So as a rule of thumb, their "performance envelope" tends to run across a 200 feet-per-second range or better. The 135 is designed to expand at 825ish, does 850 - 875 from a 2", guesstimate 925 - 950 from your 4" which is right smack in that slug's "sweet spot". This also suggests that running the 125 Gold Dot at wild speeds like BuffBore plans is a basically good idea...but I like their 158 even better
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The reason the 147 Gold Dot concerns me is, I know these are going to need 850 - 900ish and I'm just not sure you'll get that...esp. in those rare cases where you take a 50yd shot and the round loses 50fps or more on the way.
Since the 135 isn't running at the top of it's performance range and can go faster without coming unglued, I'd use that in a 4" tube over the 147.
Hmmm...lemme make sure I'm clear here: where possible, run a round in the MIDDLE of it's known velocity range versus at the extreme top or bottom. In a 2" barrel gun, you basically can't, you're doing good if you can get into the bottom (the BuffBore 158 may prove an exception as it works at 850 and you're pulling 1,000!). But with a 4" barrel, you CAN get into these slug's performance envelope...way deep in, with a lot of loads. BUT the 147 Gold Dot will still be at the bottom. When everything goes right, it'll kick butt but things do NOT always go right...heavy clothes, barriers, long range or some combo will conspire to Murphyize you. If your round is 100fps over it's gotta-have-it minimum, you're much more heavily Murphy-proofed than otherwise.