I have a 300 blackout ar pistol but I recently picked up a cz 527 thats ready to go designed to fire subsonic 300 blackout.
I think I want to swap barrels to 300 hamr, Ive got a grnedel,a 6.8, and the 6 arc.  Im not lacking a larger ar 15 cartridge.
Reloading is no big deal, so thats not going to be an issue for me.

Whats the hive say?

With seven HAM'Rs sitting here I'm a bit bias.  By having that many it should tell you I'm rather fond of the cartridge.  The only people that talk it down are people that have never tried it.

So you obviously shoot subsonic since your new CZ is a designated subsonic gun?

If so stick with Blackout.

If you just want something new to tinker with go ahead and play around. 300 hammer is cheap to get into, just not to shoot. In real world scenarios it won't do anything a 300 Blackout / 7.62x39 won't already do.

I was told 300 hamr is mainly supersonic.

300 hamr is only supersonic.

What do you want out of it and how did you narrow it down to the HamR?

Any reason not to just go 7.62x39? Or just neck up one of your rounds you are using? 30 HRT I think is 6.8 and 30 Gremlin or 30 ARX are Grendel based I think.

OP indicated he reloads.  If that is the case, it's not more expensive to shoot 300 ham'r.  Factory ammo might be cheaper with 7.62x39, but reloading cost won't be much different for any of them.

Other than throw the same bullet weight at a much faster velocity, sure

Much faster than x39? Even with the smaller case?

From Wilson's site:

300 HAM'R 16.25” Barrel
Sierra 125gr SBT 2520FPS MV, 1763FP ME
Hornady 150gr SST 2290FPS MV, 1747FP ME

7.62x39 16.25” Barrel
Remington 125gr Cor-Lokt 2365FPS MV, 1552FP ME
Winchester 150gr Razorback XT 2056FPS MV, 1408FP ME

Yes.  The max pressure of 7.62x39 is lower than 300 Ham'r.  Comparing factory ammo, 300 Ham'r tends to be faster for the same bullet weight.  I don't own 7.62x39, so don't know how far it could be pushed with handloads, compared to the 300 ham'r.

I will add 2700 fps with a 110gr for 300Hamr

I handload for both.

You can push 7.62x39 just as fast as 300 hammer with AA2200 or Axcurate TCM.

300 Blackout can use the 110 TAC-TX, 300 hammer can't. It really diminishes the terminal difference in these two cartridges.

No magic or juju here. Just modern loads.

Wilson's data might be a little tilted towards the hammer, just saying.

Fun little cartridge, but let's not doing the Variant thing where we make cartridges better than they really are because we really like the name or some crap like that. Let's call it the LRRPF52  effect.

300 Hammer/350 Legend/7.62x39/300 Blackout all have about the same killing power. Take it from a guy who has killed a dump-truck load of a critters with each.

I'd be interested in what bullet/powder/velocity you are obtaining with each.  Also, with what barrel length.  I know what is possible with the 300 Ham'r and 300 BLK, but have no idea about the 7.62x39 since I don't own one.  You can even throw in 6.8 SPC if you'd like.  300 Ham'r, 6.8 SPC, and 300 BLK are the AR15 variants I've spent the most time evaluating.

I'm surprised that you see better performance with Accurate 2200 for the 7.62x39 than CFE BLK.  While I've not actually reloaded for the 7.62x39 or 30 HRT, most seem to believe they get best performance with the same powders used for 300 Ham'r.

Handloading opens many options, but I'd wager that less than 5% of AR shooters handload so let's keep it in perspective.  With factory, off the shelf ammo, the HAM'R exceeds the performance of both the BLK and x39.

I also handoad, and would still go with the HAM'R over both of the others.  But, I don't shoot suppressed.  If I did, I might then lean to the BLK for duality.

Good to know on the 110 tac tx.  What about the 120?

The context is that OP made it clear he reloads so I’d say that’s relevant.

Is the 110 too long for the Hamr?

Very true.

Maybe I'm wrong but I assumed 90% of folks shooting 300 hammer were handloading since it's a bit of a boutique cartridge. Not 17 fireball rare but 6.8 SPC rare. WC does a very good job with factory ammo, in that handloading provides very little gain.

7.62x39 is a consistent 2450fps with a 125gr bullet across the board using good American components and brass cases.

I like AA2200 and TCM more  due to th3 fact that CFEBLK is about as stable as a bipolar teenage girl. Shit is all over the place.


My family and I have had such wonderful success with the 110 against black bear and whitetail from 30 yards to 200 yards that I've never felt the need to try the 120.

110s over Win296 are going 2490fps from a 16" barrel.

Thats what Im wondering, as I dont see load data for it nor the 120.

Yes, just about all pointy 30 cal bullets are. I think the hammer can use a couple bluntish light low b.c varmint bullets, besides that it's limited to light 30-30 bullets.

Easily the biggest handicap of the cartridge.

I've single loaded a 110 TAC-TX load for my hammer that was lights out at 100 yards, but it was just for fun.

Thats a killer for me then.  Guess Ill stick to 300 blkout in my ar.  Thank you.

There are several "pointy" bullets suitable for the HAM'R, such as:

95gr Lehigh CC
110gr Hornady V-MAX
110gr Lehigh CC
115gr Sierra HP
115gr Lehigh TXC
115gr Lehigh TME
125gr Speer TNT
125gr Lehigh CC
135gr Hornady FTX
135gr Speer Bonded
150gr Hornady SST
150gr Speer Gold Dot
150gr Speer BTSP

All can be pushed 250-350fps faster in the HAM'R than in the Blackout

The Speer 125 TNT is pointy

The Ham'r is a 250ish yard cartridge that will out perform anything 300blk if sub sonic does not matter.

With my samples of one 300hamr barrel and one 16" blackout barrel this is not accurate.

With the same projectiles and powders optimized for each cartridge I see 100-150fps faster with the hammer.

Exactly what "performance" are you referring to? Internal? External? Terminal? Drop? Drift? All of the above?

Because it doesn't matter. If the reduced drop is your justification, going to the hammer over 5.56 is a foolish choice in everyway.

If it's hunting, do what I did and shoot a bunch of medium game with both. They kill the same at about the same range. Absolutely no discernable difference between these two cartridges ability to ethically harvest game at appropriate ranges.

"Hammer is lethal for another 50 yards!" Maybe ish could be possibly?

Either way, if that extra last 50ish yards are even a consideration, BOTH of these are the wrong cartridge, and you need to be into something like a Grendel or 6.8 SPC, something with a little forgiveness both externally and terminally.

I like cartridges with cool names too. Let's focus on it and not LRRPF52 this down a toilet bowl.

You are not wrong, but let's be real.  Do 1 in 20 members here handload?  I doubt half that many do.  I do, and, as you say, can close the performance gap.

But, when it comes to available "factory" loaded ammo the gap widens.

To me it boils down to "suppress or not to suppress".  If you never plan to suppress, get the largest case you can afford to feed.  

Assume a 16" barrel and published factory ammo velocity

110gr V-MAX
Blackout 2375fps
HAM'R 2525fps

Hornady 135gr FTX
Blackout 2085fps
HAM'R 2380fps

150gr Fusion
Blackout 1900fps
HAM'R 2275fps

If we are still going to simply compare cartridges, why exclude the 7.62x39?

Cheaper, widely available, and almost matches the hamr with factory ammo, I will argue it will exceed 300 hamr performance handloaded, but as mentioned before not everyone handloads.

....but I'll drop the big question again.

What will one of these cartridges "do" on game the others won't? They are 200 yard hunting rounds. If one has an inch less drop or not it just won't matter within reasonable ranges.

The answer is nothing. Black bear, whitetail, hundreds of coyote, porcupine, ground hog, red squirrel, partridge, fox, I asked every single one of them despite nearly identical wound channels and exit holes and not a one could tell the difference.

I'd love to stay on track about the merits, accomplishments, technical data and anecdotes on how we use our 300 hamr, but we have all seen the past 3 threads start up called 300 hamr which turns into a comparison or 300blk vs 300 hammer by reply #5, which there are about 4000 threads in the archive to comb over.

For those who have a discomfort with the .300 BO / 5.56 mischamber potential, couldn't a .300 HMR run with this seated deep, as a subsonic?  It's a 220 gr blunt-ogive .30 cal bullet, that should still seat and neck-engage I would think.

https://www.goldcountryammo.com/product/30-caliber-hunting-bullets-220-grain-308-diameter-gold-country-razorback-serrated-copper-jacket-flat-nose-bullets-50-count/


(as one example)

here's another:


BC probably sucks, but then, not sure how big a difference that makes, since it's a 200 yard engagement round when subsonic anyway, so is the trajectory for a 100 yard hit really all that much worse?

Never used the top Soft Point Razorback, but getting that to feed consistantly might be a bit dicey.

The second Nosler BT I believe is either discontinued, or you never ever see them in stock.

Tried getting them to group in three Blk barrels without any dice. Very inconsistent bullet and Noslers sad attempt at an expanding subsonic.

I personally exclude it because I want to stick with .308 diameter bullets.  Perhaps you can get barrels with different bore sizes, but I've simply preferred not to mess with it.  I started out with 300 BLK, and wasn't happy with the supersonic performance.  I tried the 300 Ham'r, and it was better.  I liked that I could use the same 300 BLK mags and bullets that I already had.  I'm actually having a 30 HRT barrel made to see what I can get from it.  Again, it will use many of the same bullets I use in the other two.  Different mag and bolt, but at least the same as I am already using in 6.8 SPC.

For handloaders, we tend to push things to what we want, based on our perception of the pressure we're running.  While I'm not 100% sure, because I don't have pressure testing equipment, I suspect that with equivalent pressures you'll always tend to have a 200 fps difference or more with a 16" barrel.  Perhaps @BWilson can shed more light on this.  Another question for Bill would be whether the 110gr Vmax is loaded at 2525 fps for the 300 Ham'r because of pressure limitations, or other considerations.

The difference in 300 BLK to 300 Ham'r is that dependent on the bullet/load, the 300 Ham'r has the same velocity at somewhere between 50 and 100 yards, as the 300 BLK has coming out of the barrel.  Individuals have to decide for themselves whether that range difference matters for them.

To help Campower, given his concern regarding velocity spread with CFE BLK, you have to fill the case up, and compress it to get low SD/ES.  The more you compress CFE BLK, the better it performs.

Blackout has a SAAMI max pressure of 55kpsi and the HAM'R has a SAAMI max pressure of 57,500psi (same as the 204 Ruger), however at WC we try to keep our loads in the 54kpsi range for safety and I'm sure the major ammo mfg keep their Blackout loads in this range too.

One thing that I haven't seen addressed is terminal bullet performance (something I do  LOT of testing on since purchasing Lehigh Defense). Most hunting bullets of any brand or type are not designed to perform properly with a impact velocity below 1800fps, some will perform down to 1600fps, but rarely below that. Solid copper high weight retention bullets like the Barnes TSX/TTSX will have a narrower performance window that bullets designed to come apart and lose weight. As far as HAM'R suitable bullets go, the softly constructed Sierra 135gr HP-V probably has the largest operational velocity window. Obviously if you only start with a MV of 1900fps with a 150gr Blackout your effective range is pretty short. Bottom line, the higher the MV the longer the effective range for any given bullet.

Handloaded 300 Ham'r velocities

110gr 2700fps
125gr 2500fps
150gr 2300fps

With the 1-13 twist I can get 10 shot MOA groups @ 100y.  1-15 is supposed to be more arcuate with 135gr or less.

I can push (cheap) 120gr plated 300blk bullets past their recommend velocity with the slower twist.  They make for good plinking and fireforming bullets.

Roughly the same I'm seeing with my 18" 300 hammer.

It's give or take 50fps faster than equally loaded 7.62x39 loads, and 100-150fps faster than my blackout loads. With quality factory ammunition such as WC and Underwood I see the same differences, for whatever its worth.


Attached File

I was loading a batch of 150gr SSTs (Savage Variant) for the 300 Ham'r this morning and shot a string of 10 over the Garmin chronograph.  New nickel plated sig brass, sized/chamfered, then loaded.  CCI 450 primers, COL range 2.252" - 2.258".  Charges thrown with an autotrickler, 25.81gr CFE BLK.  No crimp.

I chose 25.81gr for the Autotrickler setting, because the A&D FX120i scale measures in .02gr increments, and throws come out 25.80gr or 25.82gr.  25.8gr of CFE BLK is the max charge for the 150gr SST per Wilson Combat load data.  Nothing special was done to sort the bag of 100 pieces of brass from Wilson Combat, or box of 100 bullets from Hornady.

Wilson Combat 300 Ham'r 1:13 twist 16" Ranger barrel with a Vox K suppressor using a Plan A mount and EZ brake.  The suppressor/mount adds about 3.75" to the end of the barrel.

From Garmin CSV Export :
Rifle Cartridge, 150.0 gr
#      SPEED (FPS)      Δ AVG (FPS)     KE (FT-LB)    POWER FACTOR (KGR⋅FT/S)         TIME
1      2316.2               -7.5                1786.5             347.4                                       10:09:45 AM
2      2337.7                14                 1819.8             350.7                                       10:10:17 AM
3      2320.6               -3.1                1793.3             348.1                                      10:10:36 AM
4      2316.5               -7.2                1786.9             347.5                                      10:10:49 AM
5      2315.7               -8                   1785.7             347.3                                     10:12:32 AM
6      2341.1               17.4                1825.2             351.2                                     10:12:38 AM
7      2314.8               -8.9                1784.4             347.2                                      10:12:50 AM
8      2325.9                2.2                1801.5             348.9                                     10:12:56 AM
9      2333.9              10.2                1813.9             350.1                                     10:15:08 AM
10     2314.6              -9.1                 1784               347.2                                    10:15:13 AM
-
AVERAGE SPEED      2323.7
STD DEV                      9.8
SPREAD                      26.6
AVERAGE POWER FACTOR  348.6
PROJECTILE WEIGHT(GRAINS)   150
SESSION NOTE150gr SST 25.81gr CFE BLK
-
DATE "March 2 2024 at 10:06 AM"
All shots included in the calculations