300HAMR BARREL TWIST

[bobcat93]

Need 3k, might be time for a 30 BR?

IDK from what i read it will take on average something like a 51 gr case capacity to push a 308dia bullet, 125 gr, over 3000fps.
Thats reaching 30-06
I was thinking the smaller the case the higjer the operating pressure= more velocity. But things get weird in the 308 world.
You will blow up your gun before you reach high velocity with a small 308 cartridge hahahaha..
Its just a different beast

 

[bobcat93]

Need 3k, might be time for a 30 BR?

I discussed that one already..it wont do it.. a 30 dasher might. But i believe even that is only 41gr case capacity

 

[Oso]

My pleasure … it was good visualizing it. Supersonic bullets designed specifically for 300BO usually feature a long angular profile (less radius… more triangular). This modified profile is to reduce the large gap between supersonic loads and 300BO chamber, which is made to handle long supersonic bullets.

My initial post above includes a link to Wilson Combat’s load data. It includes all bullet that are known to fit within 2.26” restriction. The list was initially compiled by WC and input/feedback from participants on 300HAM’R thread.

I haven’t seen any discussion or list of additional bullets that could be used in bolt rifle with long COAL. Honestly, it’s not surprising since until now (Savage rifle) there really hasn’t been any bolt rifles (other than someone’s personal custom build) chambered in 300HAM’R. When these rifles hit the market then I expect to start seeing this topic explored on the 300HAM’R thread.

 

[C.E.Smith043]

So go with what Willson came up with?
Order a 1-15 twist?
And that will cover the 100gr-150gr bullets

That's what I did.

 

[Thauglor]

IDK from what i read it will take on average something like a 51 gr case capacity to push a 308dia bullet, 125 gr, over 3000fps.
Thats reaching 30-06
I was thinking the smaller the case the higjer the operating pressure= more velocity. But things get weird in the 308 world.
You will blow up your gun before you reach high velocity with a small 308 cartridge hahahaha..
Its just a different beast

Things do not get weird in the 308, there is no different beast here, unfortunately you dont know quite a bit when it comes to the physics involved or about reloading but glad you are asking questions. The 300 hamr and 300bo and other smaller based 308 cartridges lose velocity, no way to change that without going to what sig did with the metal case head and 80,000 psi.

It is gas volume and pressure that determin speed, these smaller cases dont have the gas volume without going crazy high psi.

A standard 308 winchester does everything you are looking for, you are buying into the marketing of these new cartridges.

 

[Oso]

So go with what Willson came up with?
Order a 1-15 twist?
And that will cover the 100gr-150gr bullets

If this is for a bolt rifle then you’ll have a longer mag length so have ability to play with different / longer bullets. Also, if you think you might want to play with heavier bullets then will want a faster twist. Might be worth considering 1:13 and if can’t find it look for 1:12faster

 

[bobcat93]

Im on there web now..about ready to go.my cheap ass is looking for a discount code and some place to add an AARP discount, maybe they take a Buckeye Card for Seniors hahahahaha
Oh! I did come across a parts kit i made in about 2008 and shoved in a grip !, so that was a nice find.
Even have a complete spare lefty bolt from Stag with a firing pin in it..heck thats probably 120$ by now..and
thats is not a part that is easily acquired at the moment.
There was a time when only Stag made ambi barrel extensions, so when i needed a barrel from Krieger i had to send in the ambi barrel extension and a lefty bolt
So i have those parts rolling around still..
That made me happy..
Now i believe the industry standard are all barrel extension milled ambi? I could be wrong but i believe thats what i was told by kreiger.i forget could have been Some one from DPMS.
I use to be really into it..sweating to death in summer heat and dragonflys @ Camp Perry
Good memories & and lots of friendly people.
It didnt matter who you got teamed up with ..by the time it was done, the last thing you wanted to think about was a gun..
Its a lot to take in..

 

[bobcat93]

Ok thats done ..also the bullet i asked about
The seirra 125gr. #2120 is listed with load data by serria. According to Seirra data looks like it fits in the mag

This is from Willson Combat website as they were kind enough to list suggest reloading bullets for the 300Ham'r
125gr Sierra SPT PH (extremely accurate, great all-around bullet)

If you new to the 300Hamr (like me) there is listed information right on Willson combats web site.
I didnt see load data but list of suggest tested components.

 

[bobcat93]

My pleasure … it was good visualizing it. Supersonic bullets designed specifically for 300BO usually feature a long angular profile (less radius… more triangular). This modified profile is to reduce the large gap between supersonic loads and 300BO chamber, which is made to handle long supersonic bullets.

My initial post above includes a link to Wilson Combat’s load data. It includes all bullet that are known to fit within 2.26” restriction. The list was initially compiled by WC and input/feedback from participants on 300HAM’R thread.

I haven’t seen any discussion or list of additional bullets that could be used in bolt rifle with long COAL. Honestly, it’s not surprising since until now (Savage rifle) there really hasn’t been any bolt rifles (other than someone’s personal custom build) chambered in 300HAM’R. When these rifles hit the market then I expect to start seeing this topic explored on the 300HAM’R thread.

Im so slow in my old age..you already said everything i just found out this evening when ordering a barrel ..im going with the Wilson AR barrel. I thought about taking a barrel off my savage or my AR ..i love my savage the way i have it and dont want to touch it. My AR is amazing but im kind of board with it..so ive decided to change that up..although it has a new kreiger on it ..and its pretty haha

 

[Oso]

Ok thats done ..also the bullet i asked about
The seirra 125gr. #2120 is listed with load data by serria. According to Seirra data looks like it fits in the mag

This is from Willson Combat website as they were kind enough to list suggest reloading bullets for the 300Ham'r
125gr Sierra SPT PH (extremely accurate, great all-around bullet)

If you new to the 300Hamr (like me) there is listed information right on Willson combats web site. I didnt see load data but list of suggest tested components.

Bobcat93 - Welcome to the HAM’R Club. See below for the Load Data as well Factory Ammo.

This is the Wilson Combat Load Data for 300HAM’R from their website.
Wilson Combat - 300HAM’R Load Data (link)

These load are same that WC uses for their factory ammo that they sell.
Wilson Combat - 300HAM’R Factory Ammo for Sell

 

[Oso]

Ok thats done ..also the bullet i asked about
The seirra 125gr. #2120 is listed with load data by serria. According to Seirra data looks like it fits in the mag

This is from Willson Combat website as they were kind enough to list suggest reloading bullets for the 300Ham'r
125gr Sierra SPT PH (extremely accurate, great all-around bullet)

If you new to the 300Hamr (like me) there is listed information right on Willson combats web site.
I didnt see load data but list of suggest tested components.

The Sierra Pro Hunter (#2120) was identified early on as very accurate in 300HAM’R. Its shorter squatter profile meant that it could fit within 2.26” coal limit. It was also very effective hunting round at HAM’R velocities. However, a couple of years ago Sierra modified the bullet by adding a heavier copper jacket. This benefitted cartridges, such as .308 Win, that fired the projectile at much higher velocity, but made it less effective ( decreased expansion) at HAM’R velocities.

It still works great on targets, but less effective as hunting round as reported by Wilson Combat in 300HAM’r thread. If you have older stock of these bullets then not a problem.

 

[bobcat93]

The Sierra Pro Hunter (#2120) was identified early on as very accurate in 300HAM’R. Its shorter squatter profile meant that it could fit within 2.26” coal limit. It was also very effective hunting round at HAM’R velocities. However, a couple of years ago Sierra modified the bullet by adding a heavier copper jacket. This benefitted cartridges, such as .308 Win, that fired the projectile at much higher velocity, but made it less effective ( decreased expansion) at HAM’R velocities.

It still works great on targets, but less effective as hunting round as reported by Wilson Combat in 300HAM’r thread. If you have older stock of these bullets then not a problem.

Thats right!..the hamr is slow in comparison and the bullet needs the be above 2400fps to work correctly like in 30-30 velocity range
I think i was reading that on seirra website

 

[dellet]

Thats right!..the hamr is slow in comparison and the bullet needs the be above 2400fps to work correctly like in 30-30 velocity range
I think i was reading that on seirra website

This is simply not true

 

[Dufas]

"you are buying into the marketing of these new cartridges." Not really. Cost to reload 308 is 2x & I don't need the 308 for hogs and yotes.

 

[bobcat93]

Holy smokes! Last time i purchased a set of dies they were 65$..few years later 85$ few years later 110$..now 2026 a set of 2 dies is 150$ pus shipping..
For standard redding dies.
Looks like im going lee, and i see starline makes 300hamr brass..no sense destroying beautiful heavy duty new lake city brass is there?.
I dont know what i was thinking .
Before it all sunk in the the 300hamr case is longer then a fireball case, and shorter then a 223rem. DUH!..
JESUS
Before i order dies i have a real stupid question.

I do have bushing neck dies 223, 221fireball.

Can a fireball bushing die be used to form 300hamr brass..or any die combination
I may already have.
This explains alot of the confusion it was 100% on my end because i wasnt paying attention and didnt do enough homework. Before i brought my question to you guys.
I have no problem admitting when i make a mistake..
I was thinking the hamr was more like the 350 ledgend or a 30TCU
But its not! Its a completely new odd ball..and i love that.
Even more exciting to me.
I did pick up a batch of new coffee ive been drinking for the past week..
Can i blame it on the coffee..

 

[FrankG]

Bullet length dictates twist. Not bullet weight.

Velocity plays a part as well.

So doing a twist calc on 125 Sierra TMK's these are the numbers I get.

At 3000fps that bullet needs a 16.632 min. twist.

At 2600fps that same bullet needs a 14.476 min. twist.

At 2400fps that same bullet needs a 14.168.

Sorry but I don't see you pushing a 125gr bullet at 3000fps out of the 300 Ham'r without have major pressure issues and safety issues with the firearm.

Watch what your doing and be safe first and foremost.

Later, Frank
Bartlein Barrels

 

[bobcat93]

This is simply not true

Hold on..let me see if i can find the data i was reading.

Here look this over

Based on Sierra Bullets' specifications, the 125-grain .308 diameter #2120 Spitzer Pro-Hunter bullet is versatile, with suggested usage depending on the application:
Varmint/High-Velocity Usage: The bullet is designed to be very destructive at high velocities, with a ballistic coefficient profile provided for velocities of 2800 fps and above.
Medium Game/Hunting Usage: When loaded to medium velocities (often, this implies lower than maximum .308 Win speeds, or roughly in line with 30-30 level velocities), it is recommended as an excellent low-recoil option for medium game.
Performance Range: The bullet is designed for reliable expansion, with specific performance noted between 2000 and 2800+ fps.
The #2120 Pro-Hunter is noted for having a medium-weight tapered jacket and is particularly popular for Hunter Benchrest.

 

[dellet]

Hold on..let me see if i can find the data i was reading.

Here look this over

Based on Sierra Bullets' specifications, the 125-grain .308 diameter #2120 Spitzer Pro-Hunter bullet is versatile, with suggested usage depending on the application:
Varmint/High-Velocity Usage: The bullet is designed to be very destructive at high velocities, with a ballistic coefficient profile provided for velocities of 2800 fps and above.
Medium Game/Hunting Usage: When loaded to medium velocities (often, this implies lower than maximum .308 Win speeds, or roughly in line with 30-30 level velocities), it is recommended as an excellent low-recoil option for medium game.
Performance Range: The bullet is designed for reliable expansion, with specific performance noted between 2000 and 2800+ fps.
The #2120 Pro-Hunter is noted for having a medium-weight tapered jacket and is particularly popular for Hunter Benchrest.

Thanks for making my point so easy.

You already answered your own question and just won’t see it. I’m not sure where you are getting your 30-30 data, but you might want to compare cartridge velocities from the same source. Then actually read the test barrel lengths. Once you’ve done that, plug the bullet into a trajectory calculator and see what distance both cartridges drop below the lower threshold of 2000 fps you referenced.

Spoiler alert. You won’t find data for a 30-30 over 2800 fps.