300 ham'R on a budget

[troy fairweather]

Anyone hear ever ream out a 300 blackout barrel to 300 hamr. Don't see any reason it won't work I know the twist is different and the blk are normally carbine or shorter gas tube length.

A 1-7 or 1-8 twist should be fine compared to the hamrs 1-15" twist I believe they have, don't think it has the power to over spin the lighter bullets and the fast twist should be nice for some heavier bullets for some monos. A over gas problem should be fixed with a adjustable gas block and a heavy buffer.

brass should be easy to make from 223/5.56 and think guys use a 300blk mag for best feeding.

I haven't priced what a 300 hamr barrel runs hard these days anyway, but if bet 300blk barrels are cheaper.

so anyone do this?

 

[mcb]

The only minor issue I can think of it the resulting 300 BO to Ham'r barrel might be over-gassed. An adjustable gas block solves that problem if that turns out to be true.

Give it try and report back to us.

 

[troy fairweather]

The only minor issue I can think of it the resulting 300 BO to Ham'r barrel might be over-gassed. An adjustable gas block solves that problem if that turns out to be true.

Give it try and report back to us.

Have to see how money goes, last year I could probably got a cheap 300blk barrel for under $50. Maybe twice that, about $40 for the reamer and gauges to rent. So the margin saved is less now, but still think it will be $60-$100 cheaper.

 

[Armorer 101]

If the original barrel is nitrided or a similar hard coating you can not use a high speed steel reamer and a carbide reamer may be chipped by trying to recut the coated chamber. The result could make a re-barrel with a new barrel, way less expensive, in the long run.

 

[troy fairweather]

If the original barrel is nitrided or a similar hard coating you can not use a high speed steel reamer and a carbide reamer may be chipped by trying to recut the coated chamber. The result could make a re-barrel with a new barrel, way less expensive, in the long run.

Yup I've already thought that out, either I'd get a stainless or a cm that's blued/ phosphate.

 

[BBBBill]

I would be very leary of that working due to the differing gas port locations. I would not expect an adjustable gas port to solve any over gassed issues. There more to the gas cycle than simply port location and pressure. The powder's burn rate and pressure curve are important elements in that.

If I were flush with cash it might be an interesting experiment. If not then the risk of failure might be too much t orecover and carry on with a new barrel.

 

[BreechFace]

I would be very leary of that working due to the differing gad port locations. I would not expect an adjustable gas port to solve any over gassed issues. There more to the gas cycle than simply port location and pressure. The powder's burn rate and pressure curve are important elements in that.

If I were flush with cash it might be an interesting experiment. If not then the risk of failure might be too much t orecover and carry on with a new barrel.

There's not many options for gas port location. Likely, one could find a cheap 300 BO barrel with a port location that is common for the 300 Hammer, I would think. But your point is well taken.

Aside, from the 300 BO barrels that are pistol gas length which I would avoid if doing such a venture as @troy fairweather is proposing.

Looking on Wilson Arms website it looks as if the 300 Hamr uses mid-length and intermediate length gas systems for 16" and 18"/20" length barrels respectively.

 

[mcb]

I would be very leary of that working due to the differing gad port locations. I would not expect an adjustable gas port to solve any over gassed issues. There more to the gas cycle than simply port location and pressure. The powder's burn rate and pressure curve are important elements in that.

If I were flush with cash it might be an interesting experiment. If not then the risk of failure might be too much t orecover and carry on with a new barrel.

An adjustable gas block solves any potential over gas problems very nicely. The pressure curves between the two are very similar, both operate as the same SAAMI MAP pressure (55ksi). Its very likely you would not need to change the gas system at all. Both of my 300 BO's (carbine and pistol) will run everything from subs to supers with and without the suppressor. I have little doubt the slightly higher gas port pressure of 300 Ham'r at the same length gas system would be at worst case slightly over gassed and need a slightly smaller gas port (or adjustable gas block) but would likely run fine unchanged. A quick dabble in Quickloads and gas port pressure probably is only different by 10-15% when using similar bullet weights between the two cartridges.

ETA: The gas port pressure of my subsonic ammo is almost half the pressure of my super sonics ammo.

 

[troy fairweather]

https://www.bearcreekarsenal.com/bc...gas-system-w-1-8-twist-750-gas-block-diameter

It's not hard finding carbine length 300blk barrels, this barrel from bca was under $50 a year or so ago, there may not be many barrels cheaper at them moment. The Wilson barrels are as little as $225 I believe so after reamer rental there's not much difference in price.

 

[edwardware]

A 1-7 or 1-8 twist should be fine compared to the hamrs 1-15" twist I believe they have, don't think it has the power to over spin the lighter bullets and the fast twist should be nice for some heavier bullets for some monos. A over gas problem should be fixed with a adjustable gas block and a heavy buffer.

brass should be easy to make from 223/5.56 and think guys use a 300blk mag for best feeding.

Context: I shoot a 7.62x40WT, the older twin on the 300H'mr.

It sounds like you are at least cognizant of the issues. I observe that my 7.62x40WT has a very narrow powder charge and burn rate window, the most unforgiving gas-op weapon I've touched.

The twist will raise pressures, but not enormously.
Brass is cake, and 300BO mags are necessary.

But, I'll bet if you hang out at Mad Dog Weapon Systems' forum, you'll get a chance to snag a correct barrel for cheap.

 

[Dima Prok]

Context: I shoot a 7.62x40WT, the older twin on the 300H'mr.
... I observe that my 7.62x40WT has a very narrow powder charge and burn rate window, the most unforgiving gas-op weapon I've touched.

Something must have been wrong with your setup. My 7.62x40WT with generic upper, gas block and Brownells BCG ran flawless. I shot a lot of lead projectiles with it and and cycling was flawless and accuracy was great. I used 4198, 1680, shooter's world blackout and even shooter's world heavy pistol (similar to H110) produced sub moa group with cheap 120gr copper plated bullets.

 

[RKRCPA]

Something must have been wrong with your setup. My 7.62x40WT with generic upper, gas block and Brownells BCG ran flawless. I shot a lot of lead projectiles with it and and cycling was flawless and accuracy was great. I used 4198, 1680, shooter's world blackout and even shooter's world heavy pistol (similar to H110) produced sub moa group with cheap 120gr copper plated bullets.

What kind of velocities are you getting with these powders. I stocked up on 1680 because it seemed like that was the best for maximum velocity. I'm using the Sierra 125gr. SPT for hunting loads.

 

[Dima Prok]

What kind of velocities are you getting with these powders. I stocked up on 1680 because it seemed like that was the best for maximum velocity. I'm using the Sierra 125gr. SPT for hunting loads.

I haven't had chance to hunt, where I live it's too populated. With lead cast bullets NOE HTC310-135-RN-BY3 works great, also 150gr version, with that particular alloy they dropped 136.5gr and loaded over 23.5gr of 1680 with 16" barrel shot 5 average velocity 2330fps. Powder coated and gas checked bullet. I found that lead bullets with same powder charge shot faster than jacketed. I can't find exact same charge with 125gr TNT but with 24gr of 1680 average 5 shot velocity was 2235 fps, that's 95fps slower and with 0.5gr bigger charger and lighter bullet too (125 vs 136.5). I was running in to really flat primers so 24gr was my limit, I always wondered how the load data from WC called for 25.6gr max and I found out later with HAMR - you really need to use magnum primers like CCI 450 as they are stronger and won't flatten. I did push these 125gr TNTs faster with 300 HAMR barrel and bigger charges but it also it was 20" so I can't really compare. With Hodgdon CFE BLK powder you can achieve faster velocity but I found that I have no idea how they able to stuff so much powder in to the case, if you tap the case you can settle some of the powder but I found that I was getting the powder compressed so much it was pushing back on the bullet, had to adjust the seating die lower in order to get same seating depth. I don't like that. There is also Shooter's World SOCOM which I finally was able to score 15lb but haven't tested, however it's also great 300 blackout powder and can be used for 7.62x39. I got really lucky just recently and picked up two 8lb jugs of 1680 locally for really good price $23/lb, I like this powder, it works really good with cast bullets as well as jacketed and I'll continue to use it. I switched to 300 HAMR but there is little advantage, mostly because I was able to get 20" barrel that I always wanted, I also got 300 HAMR barrel now for my Ruger American Ranch that used to be 300 blackout but I haven't tested yet because of the weather but with longer magazine length I should be able to use Hornady 125gr SST bullets that I have a stash of.