How do these bullets compare for penetration and expansion?

SST is more explosive usually doesn’t leave an exit wound, interlock penetrates deep, good cup and core bullet. Those are just my observations on a few WT deer. Others have much more experience with them.

I've used a lot of Interlocks, and a handful of SSTs.

The Interlocks have been great for me in the times I've used them. Not always an exit, but plenty adequate expansion and penetration in the 2500-3000 fps range.

I've had several 95 SSTs come apart from a .243 Win at around 50 yards, and they made a mess out of the 2 deer I shot with them using my 7WSM. Dead deer, but I wasn't impressed at all.

I'd definitely lean towards the IL for big game.

I load the 165 interlocks for my dad's 300 Win mag and 139 interlocks for my brothers 280 and they have zero complaints. Probably not the most accurate loads out there but definitely minute of whitetail. I shot 165 sst for years in my 30-06 again with zero complaints. Only had 2 not exit-severe quartering towards mature buck at about 50 yards, tucked inside near shoulder and found the bullet at back of opposite ribs on other side, and another mature buck that was quartering away at 150 or so and hit in neck. Broke numerous vertebrae and ended up at the base of the skull. Lots of drt with both loads and when needed blood trails are plenty adequate. Definitely would not recommend shooting shoulders with the sst but for the ribs it's great. Plan on shooting them again this year.

I've used the 140 grain SST in my 270 Win with great results. I got exits and great blood trails. I only shot whitetails with them, though.

No comparison for me Interlock all the way. But I have not shoot any of the newer SSTs and many maybe most have undergone improvements with thicker jackets and harder cores so I can not say about the current crop of SSTs.

My experience is:

I switched from Core Lokts to Interlocks when CL's were hard to get. I did this after a lot of testing, mostly on deer and antelope.

SST's had better Ballistic Coefficient and I have bought quite a few. So far only paper targets with SST's. I don't know why I was concerned with Ballistic Coefficient as I won't shoot game beyond 300 yards. (I believe doing it isn't that hard, but I like to drop them where they stand, since tracking animals and having animals suffer are both good enough reasons for me to keep the range moderate.) I'll shoot PD's and varmints at 500+ yards and they sure are smaller targets than game animals. I believe getting close to game is "the hunt". Thus "Why did I buy those SST'S?"

I had heard - rapid expansion and shallow penetration with SST's - didn't know if that was true. Thus the question.

I do not recall ever complaining about bullet performance with Interlocks. But I have heard of people not liking the Interlocks at well above 3,000 fps.

Thanks for your answers, it solidifies my thoughts on these bullets. I hope that Hornady will make their SST's perform what I'd call better performance with their SST's though.

I have read that the SST was improved, but I probably will not find out. I have no use for them. I will stay with plain interlocks, as they perform great and have for me in several calibers for many years. If they have made the SST more durable, then great, but I had them blow up on small deer in a lightly-loaded .308. I am less than impressed. I have always gotten sub-half-moa accuracy in most of my rifles using standard Interlocks, so the pretty tip on the SST is not worth the extra money. I think that they are the worst bullet that Hornady has ever dreamed up.

I've never had a 150 grain SST not to exit several smallish Carolina deer using a 30-06 which is of course light for caliber. A really big buck here is going to run 180 lbs, the average ones around 130 and the does 75 to 100. So that is a lot of overlap to your antelope. I think they are a good choice in that cartridge for light big game started at under 3000 fps. I've found SST's to be better behaved than 150 grain Core-lokts when it comes to "explosiveness", but the SST's I have been using were bought around 2012 or so.

SST puts a lot of shock on an animal, and I bump up one category in weight due to how explosive they are....no problems when you follow this procedure for Deer.

I have shot a lot of 7mm Mag 154g and 162g on deer. There is a world of difference between these two 7mm bullets as the 162 is a lot tougher than the 154. I killed three nice bucks with a 7 mag, 154 sst, loaded with a hot load of R#25 and a WLRM primer one year, they flopped.

270 win I go with the 150g sst.

243, the 95g SST is a tough bullet, good penetration and NOT immediate expansion.

30/06, I go with a 180g SST. Like RJY66, I have had the 30 caliber 150g SST not penetrate with shallow penetration, but guts were blown to pieces with the deer dead on the spot at 50 yards.

Std Interlocks are what they say a poor man's partition, I have found this to be true.

I do like the shock of the SST, but go a tad heavier on the bullet weight...animals pile up.

Interlock digs deeper. I've experienced complete jacket separation with SST's in both 7mm (7-08AI) and 270 Win on hogs at short range. Soured me on them. Have used Interlocks and A-Max's with better results.

How long ago did you have those experiences?

My recent experience is that SST's expand similarly to Interlocks.

For antelope or deer-sized critters, I have no issues using SSTs; I'd problem chicken out on anything bigger, though, and go for either a Partition or bonded bullet.

It's exactly what would happen if an AMAX and an interlock had a baby, the SST.
because that's what it is.

Do you know if the lead cores have the same hardness?

In my experience, both the AMax and Interlock are tougher bullets. My last SST experience was about 4 or 5 years ago, and maybe they have been toughened up since then, but I was unimpressed. I would say it was like an AMax and the original run of Nosler Ballistic Tips had a child that was a bit of a wimp.

Or kinda like a corelock got prison raped by an accubond, and then baby had downs.

I like both bullets.

165 grain Interlocks worked great from my .308 with a great blood trail and blood on the ground within several feet of my last .308 buck and a 50 yard run from a heart shot and that never happened with Partitions. Barnes X bullets from my 7mm-08 were terrible on deer with poor expansion and lost me my only one ever with a rifle. Again poor blood on the ground from Partitions. Accubond made a bigger entrance wound than exit and another 50 yard run. Interlocks battered the lead nose flat in the magazine, so I switched to early SST's. DRT, but no exit on that last buck, but pretty satisfying not to need to go looking for them. Rumor has it that they are a little tougher lately, so I'll likely pick up a new box for this next deer season.

May make some diffrence as to the caliber & bullet weight. My recent testing Not exactly Apples to Apples was with a Bolt action 24" Grendel pushing 123 Gr SST's VS 129 GR Interlocks & in this case the SST.s experienced jacket separation. The core lock held together, mushroomed wonderfully & retained weight was great on Water jug test. Interestingly I was experiencing greater velocity from the 129's by 100 FPS or more.

I don't think I would eat a deer shot with a STD bullet.

A rather puzzling comment........ until, I see what you did there. 😝

Tejano, you're too much!

I like SST's. I don't find them frangible, but they do lose some weight and blow big holes through stuff. If concerned about penetration, step up in weight, I guess, but I can't see the reason why, if you are actually hunting, and not just flinging lead at fleeing animals.

I worked up a load using 130gr SST's for a guy and his do-it-all 270. He gets 3150 MV and the load will print 1/2" groups for 3 shots. He's been shooting his deer and elk with these every year for several years, and still raves about them.

I've seen some lighter ones, like the 139 7mm out of a magnum or the 95 out of a 243 put baseball holes through deer. I don't eat the lungs, so I'm okay with that.

I've been loading the Interlock since the early 80's in several cartridges (130 & 140 in the 270 WIN) (150, 165, 180 in the 308 WIN, 30-06 SPRG, 300 WIN MAG) and several others. All my current stock of Interlocks are from the 1990's and early 2000's and have performed well in the deer, coyote, and hogs they have killed. I have only shot the SST in 308 WIN Hornady Custom factory ammo, killed the deer just as dead as the Interlock did. I have enough old Interlocks to last several lifetimes so I doubt I'd handload any SST's, but if I needed any I'd use them.