Twist rates for elr?

[jasent]

Angle of my shooting position to target is almost level. Temp range was 20f up to 75f with the 20 being most recently. Velocity could not be higher than I listed as it's just not possible for the cartridge I'm shooting,I'm at the high end. Also dope using both the g7 and custom drag curve has been spot on (within 1/2 min)from 100 yards to 2200 yards. Either that or I'm incredibly lucky time and time again.

 

[jasent]

http://bergerbullets.com/product/338-cal-250-gr-elite-hunter/

You can call bs if you want. I'm simply sharing my results.

 

[jasent]

No need to be sorry, we are all here to learn from each other. Folks here have taught me a lot! And I too have eaten crow.

I'm anxious to test this further with other bullets and I'm thinking about pushing the limits farther with a 6.5 twist.338. I'm sure there is a point where it starts to hurt you

 

[Deleted member 71114]

Steve

I prefer to focus towards Miller on the heavier density bullets from the .338 and up, for example the 400 grain 375 cal used had a SF of 2.16 , thats a spin rate of 302490 rpm out of my 375 Warner. I have relied on the Cold Bore program from Patagonia in which will utilize either Millers or Greenhills formulas.
When looking at density within a bullet it is very sensitive to mass weight, mass weight still trumps. I have always believed there is a balance between mass weight and speed, the BC only contributes to that. Folks are all jacked up about shooting the Highest BC bullet but for the most of them they don't understand trueing BC and still having enough horse power or gas to even think about pushing a heavier " higher BC" bullet. If you don't have the gas you don't gain anything.

A while back I ended up testing some leadcores on the 375 versus the solids it was designed for, you were out of stock so I ended up buying some from our folks in Canada. They had a tuff jacket but when testing a 16 to 7.7 gain twist which is somewhat easy on the bullet they in turn could not make it to the 100 yard target before blowing apart. I know your lead core bullets are known for having a strong core it would of been a good test. But to all reading remember a twist as tight as 7.7 is meant for solids.



HAPERC
When thinking about running solids in the lighter class bullets as your example the .264s I would be using a 25 cal conversion. Remember nothing is set in stone they are only guidelines and estimations based on testing.

A comment from above
Some who assumed or heard from someone who probably assumed as possibly stated above - seriously a solid needs to spin slower then a lead core or it tumbles - No solids need to be spun faster then the common lead cores, also the 375 Chey Tac has been preforming extremely well in the shooting world and is very comparable in cost to shooting a 338 LM and what? Anyone shooting this round is so strapped they can't afford the other necessary items to complete their build and shoot well. Its BS like this that ticks me off because the folks that are trying to learn don't know whats valid and whats not, how asinine this comment is from above.


Osoh
JH

 

[Techy]

@jasent
Thanks, I'll also need the temperature and barometric pressure of the shot along with the bullet B.C., if the G1 B.C. of that bullet exceeds .617, that bullet is keyholing or tumbling outright 95% of the time and I'll wager $1,000 to witness that proved wrong in person.

You ever watch mark and Sam after work on YouTube? It appears most their shots hit tip first? You can see the tumbling impacts when one richochets off the ground first. most appear to hit correctly.

 

[RockyMtnMT]

Steve

I prefer to focus towards Miller on the heavier density bullets from the .338 and up, for example the 400 grain 375 cal used had a SF of 2.16 , thats a spin rate of 302490 rpm out of my 375 Warner. I have relied on the Cold Bore program from Patagonia in which will utilize either Millers or Greenhills formulas.
When looking at density within a bullet it is very sensitive to mass weight, mass weight still trumps. I have always believed there is a balance between mass weight and speed, the BC only contributes to that. Folks are all jacked up about shooting the Highest BC bullet but for the most of them they don't understand trueing BC and still having enough horse power or gas to even think about pushing a heavier " higher BC" bullet. If you don't have the gas you don't gain anything.

A while back I ended up testing some leadcores on the 375 versus the solids it was designed for, you were out of stock so I ended up buying some from our folks in Canada. They had a tuff jacket but when testing a 16 to 7.7 gain twist which is somewhat easy on the bullet they in turn could not make it to the 100 yard target before blowing apart. I know your lead core bullets are known for having a strong core it would of been a good test. But to all reading remember a twist as tight as 7.7 is meant for solids.



HAPERC
When thinking about running solids in the lighter class bullets as your example the .264s I would be using a 25 cal conversion. Remember nothing is set in stone they are only guidelines and estimations based on testing.

A comment from above
Some who assumed or heard from someone who probably assumed as possibly stated above - seriously a solid needs to spin slower then a lead core or it tumbles - No solids need to be spun faster then the common lead cores, also the 375 Chey Tac has been preforming extremely well in the shooting world and is very comparable in cost to shooting a 338 LM and what? Anyone shooting this round is so strapped they can't afford the other necessary items to complete their build and shoot well. Its BS like this that ticks me off because the folks that are trying to learn don't know whats valid and whats not, how asinine this comment is from above.


Osoh
JH

Thanks for the response. The more we test the more it seems like pre copper bullets need more stability than what the Miller formula says. Particularly when the bullets get long for caliber. Our only conclusion is density of material. Then comes the dynamic stability that there is no practical way to determine.

By the way our bullets are lathe turned pure copper. No cup and core bullets here.

 

[HARPERC]

.....If you don't have the gas you don't gain anything.
.......I know your lead core bullets are known for having a strong core it would of been a good test. But to all reading remember a twist as tight as 7.7 is meant for solids.
........When thinking about running solids in the lighter class bullets as your example the .264s I would be using a 25 cal conversion. Remember nothing is set in stone they are only guidelines and estimations based on testing....../QUOTE]

Thanks for sharing the experience.

 

[Deleted member 71114]

Steve

I was thinking of Rocky Mountain Bullets, George had some leadcores as well as solids in his line. So I guess you can drop the Hammer on me for that one.


Cheers
Osoh

 

[NEMTHunter]

A while back I ended up testing some leadcores on the 375 versus the solids it was designed for, you were out of stock so I ended up buying some from our folks in Canada. They had a tuff jacket but when testing a 16 to 7.7 gain twist which is somewhat easy on the bullet they in turn could not make it to the 100 yard target before blowing apart. I know your lead core bullets are known for having a strong core it would of been a good test. But to all reading remember a twist as tight as 7.7 is meant for solids.
Osoh
JH

Would you claim this for all calibers? Or just the .375? << This question is meant for the underlined part of your post. The reason I ask is I am running again twist to. BUT its a mild gain twist and the one you described above is a radical gain twist. Mine goes from 8.25 to 7.5. But it is a .30 cal. So far all the cup and core bullets I have shot in it have held up and made nice little round holes 100 yards. The fastest I have shot them to date was 3367 fps. The barrel maker told me that anything more then a 1" gain is to much gain for a cup and core and will eat the jacket up. Yours was a 8.3 gain. Thats a lot. LOL I am sure if your gain was less than a inch or even a 7.7 strait the bullets would have held up. The reason I ask is you stated it was built for solids. And the gain you had would (does) work fine for them.

Thanks!!

 

[Deleted member 71114]

NEMTHunter

That was in reference to the 375s in which years prior and shooting cup core type bullets a 10 twist was the norm.

Osoh

 

[NEMTHunter]

NEMTHunter

That was in reference to the 375s in which years prior and shooting cup core type bullets a 10 twist was the norm.

Osoh

Thats what I was thinking you meant. Thanks

 

[Deleted member 71114]

There was a day when most folks considered the 338LM in the same way as far as the expense involved in setting up and shooting, then in time it became the round of choice for shooting distance, Today the 375 Cheytac is the next norm for ELR type shooting, the equipment needed to run this round from actions, barrels stocks to brass and bullets are all common stream items now and carry less of the premium price tag.
Folks can get brass a lot cheaper now versus the past and from multiple sources now, primers are the same as the 338LM and there's a excellent supply of quality bullets. So to jump from a 300 to a 375 Cheytac and shoot competitive or for recreation is more comparative to shooting a 338LM if one was to be trying to increase his odds more for impacts at 1800 plus yards in any given day with the wind.
We can all shoot well on the prime mornings and evenings in calm conditions but the heavier bullet will prevail in the hands of a good shooter shooting both rifles. A favorite of mine that I wish I had time to mess around with is the 300 Norma - a excellent round for someone wanting to start shooting distance as well.

My comments here are only my opinions and recommendations from my experience pushing bullets out to 3500+ yards at times with fair success and consistency under time restraints. This is a great place to share info, but I have seen times where folks that don't know the difference and are trying to learn can be swayed some from questionable responses that sometimes are passed on in good faith but are inconsistent from what they heard or? Even at times I could be off some but my comments normally are hands on or researching that we have done in order to be more consistent in the ELR environment and at the given moment when its your turn to get it done on the firing line. There are many here that have good tips and advice to share here, we all can learn from each and everyone.

We run a couple of 375 Cheytac Improved - 375 Snipetacs with great success.

Last year I stepped up the game some and ran a 375 Warner ( a shortened and necked down 50 cal to a 375) - a excellent round for a recreational shooter wanting a laser, pushed a 400 grain with ease at 3361 fps - but a little tuff on the barrel (throat) only if you have to shoot 15 rounds none stop in 9 minutes or less. So this year we expanded the necks up to a 416 thus a 416 Warner to allow more room for the hot gases and burning powder to get through without working on the throat. If I was just plinking here and there and not in a hurry to have to repeat as many multiple shots the 375 Warner hits a target with authority.

osoh
JH

 

[Gamesniper19]

Question to you guys that are working in the 2 mile world. What is the general consensus on twist rates? Are you needing higher sg to be consistent or marginal sg?

My world of long range ends at about the 1500y mark and I prefer to have high sg for good terminal performance for hunting. This subject came up on another thread and I have been under the impression that elr target crowd is working with higher or over stabilized bullets for good performance through the transonic. Let me know if I need to be corrected.

Thanks for your input.

There is a ton of great and technical information in this thread. For most true ELR rifles shooting modern high BC well constructed bullets, 1500 yards is not really an issue.

I have done all the paper calculations and spent hours of time noodling on the miniscule. Its super fun and there is a lot to be learned. I thought, how do I make it easy?

http://bergerbullets.com/twist-rate-calculator/

Stability...can be as easy as that.

 

[RockyMtnMT]

There is a ton of great and technical information in this thread. For most true ELR rifles shooting modern high BC well constructed bullets, 1500 yards is not really an issue.

I have done all the paper calculations and spent hours of time noodling on the miniscule. Its super fun and there is a lot to be learned. I thought, how do I make it easy?

http://bergerbullets.com/twist-rate-calculator/

Stability...can be as easy as that.

That was my point of the question. My world out to 1500y is different than the true elr world. There are differing opinions of stability for elr. From our limited work at elr it is my opinion that the simple task of using the Miller stability calculators is lacking.