.375 Cheytac questions

#101
Re: .375 Cheytac questions

The 145g of 869 with a 16 fps spread and 2958 fps as the average looks to be a good load to work with ...

The BMG load has lower E.S.'s but a fair bit lower velocity...

If 869 can retain a 16fps average E.S. or even a 16fps S.D. then that looks to be close to ideal with .6 MOA performance.

A few more tests on the same case to see how the primer pocket holds out and whether extraction issues develop would be interesting.
 
#102
Re: .375 Cheytac questions

It has been my experience that extraction problems will occur before the primer pockets get loose. As a side note, it takes around 150 gr of 869 to fill the case. There is no way that is going to be a usable load. On the other hand 140 gr of BMG completely fills the case and is not over pressured. I think BMG will be the way to go.
 
#104
Re: .375 Cheytac questions

Looking at your group at a mile which was sub MOA using a lighter load of BMG ... I would have to agree with you Augustus.

It is a shame to pass up on velocity but I see your point about the air gap in the round if 150g is 100% case capacity.

The difference in "kernal" shape of the powders must be significant.

One option available to you were you to want to try to increase the load in the 50 BMG powder is to have an extended extra long drop tube on your powder funnel when tipping the powder into the case.

The longer the drop ... the tighter the powder compresses... the more can be used ...

Given the lack of pressure at 140g ... this option might be of interest ...

Personally I have never used this technique ... I am more inclined to stick with standard "capacities" ... I suspect you are likely to feel the same ...

 
#105
Re: .375 Cheytac questions

Kiwigreg, have you shortened the Chey-tac case. I the case of the 338/408 I think a shortened version would be an improvement
 
#106
Re: .375 Cheytac questions

The Jamison brass is pretty good. It does have a habit of getting sticky after 4 or 5 cycles of moderate to high pressure. Even with FL sizing it will chamber easily but get sticky on ejection. If the brass is used a couple of cycles past this point it will begin to get tight when chambering. For this reason I try to stay on the moderate side.
 
#108
Re: .375 Cheytac questions

"Leap of faith may be a gross understatement. All the testing, opinions, controversy, hate, discontent, promises, bogus claims, etc. has produced so far is the 6.5 barrel/Cutting Edge combination."...

The CE 338 tested at Gunsite was notable for its unspectacular performance. I will grant that the manufacturer's recommended twist rate was incorrect. The ZA specified barrel used in your 375 testing is a much better fit for the CE 425, and 400 grain projectiles... but the BC that you quoted is wrong. Augustus, is there a reason that you do not want to discuss the long range accuracy of either of these bullets?
 
#109
Re: .375 Cheytac questions

BMG seems to be the most consistent. It takes 140 to 142 gr to get a full case. The barrel I have been shooting lately is over pressured at 140 gr. I have been using 136 gr in this barrel. The 338/408 would be better if it was shortened by .150 to .200 this would make the use of Retumbo more efficient and I would not be surprised if a 26 in. barrel using Retumbo would equal the performance or a 30 in barrel burning BMG.

US 869 does not work well in the 338/408. Delays are common and velocity is erratic.
 
#110
Re: .375 Cheytac questions

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: PeterWilson</div><div class="ubbcode-body">

The difference in "kernal" shape of the powders must be significant.

</div></div>

ADI 2218/50BMG has very big stick kernals approx .1 grain per each IIRC, US869 is a ball powder.

US869 needs to have a fairly full case, high density to ignite properly & can be pretty temperature sensitive.
 
#111
Re: .375 Cheytac questions

The case I have based my 375 Lil'Terminator on is smaller than the Cheytac case.
I have done most of my testing at 625 yards as that is the greatest distance I can set a target up.
In testing the 400s shot the best in my barrel with a number of 3 shot .3 moa groups, most groups were around .6 -.75 moa, wind being the usual culprit.
It is fairly hilly over here & the sea isn't that far away either making wind a fairly common occurance & it usually isn't constant.....
This is shooting prone of a bipod & rear bag.
I also shot some .5 moa groups with the 425s, but haven't finished testing yet.
I have shot the 400s at rocks & had a .5moa 2 shot group at 1700 with the final shot blowing it out to a moa.
I also shot an approx 2 group at 2380, amazing waiting for the projectile to get there
cool.gif

Unfortunitly I'm still waiting for another reamer to rechamber my 375 to allow me to use better dies than the ones I made up.
Until then I really struggle to make straight ammo which doesn't help accuracy at all with such a long projectile hanging out of the case !!!!
So I have suspended testing until it is rechambered.
I'm really looking forward to being able to push these projectiles faster.
What I really like about the CE is that they have a hollow nose & they do expand, unlike most other mono-metal projectiles I have seen & used, so they can be used on game as well as targets.

CE seems to me to be the only maker selling mono metal 375s with a decent weight & BC that actually fly well......

There has been so much BS floating around for quite awhile now....

Most threads tend to turn into pissing competions about who has the highest BC etc between manufacturers/providers whos bullets haven't even been proven to fly yet......

CEs BCs are reasonably accurate I have found, their projectiles are reasonably conservative form wise but they fly...... which seems to me puts them at the head of the game currently.
 
#112
Re: .375 Cheytac questions

Thanks Greg. I absolutely agree that there was an immense quantity of BS circulating for a period of time. Actual testing, in public settings, has pretty much smothered that unfortunate impediment to honest discussion. Your report is entirely credible, but I do think that you would be stunned at the actual BC value of those bullets. Since I am set up to shoot them, I will make an effort to acquire some, and report the doppler results.

I am not ragging on CE in the least. As you have pointed out, they are a conservative design, and have performed very well for you. The fact that you are serious enough about your shooting to wait for the right barrel says alot to me.

I genuinely hope that this forum is now able to return to the level of discourse that prevailed a couple of years ago.
 
#114
Re: .375 Cheytac questions

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: damitboy</div><div class="ubbcode-body">got a chance to shoot a 375 cheytac on the range yesterday....not sure what kind of bullets. Guy invited me to shoot it, so I dashed out from behind the counter, went to the range and sent about 6 rounds through it......fun stuff!!!!

Dave</div></div>

Nice guy. Big $$ difference between that and more common rounds.

Also, this is a great thread so far. I hope it keeps going. It's really useful for those of us just starting out in this "adventure".
 
#116
Re: .375 Cheytac questions

Danger Areas depend upon what you are trying to manage as a "risk" ...

They might also depend on altitude as thinner air enables further bullet travel ...

Equally height of the firing point and level or low ground field of view ...

If you had a negligent discharge of a .375 400g solid whilst holding the rifle at 45 degrees so it was at optimum angle for a "mortar" effect on firing the bullet ... the distance is likely to be "huge" before the bullet falls to the earth ... at a guess 5000 yards to be safe ...

But if you have "range" protocols which stipulate no loading of the round until the rifle is prone and on target ... the issue of risk is managed by the height of a back stop ...

"Danger Areas" are usually considered with a "Range" certification ... allowing for transonic and subsonic flight ... 3000 yards ought to do it with a decent sized backstop at this distance ...

Checking in detail via a ballistic calculator would always be needed though ... because altitude will play a significant part in distance travelled at supersonic flight ...

However, shooting at 600 yards with a high hill as a backstop might be more safe than aiming at a 2000 yard target from the top of a hill. "Range" wise these issues are in need of factoring into any Range Assessment Safety Report.
 
#117
Re: .375 Cheytac questions

a standad .30 caliber has a maximum range (safety zone) of 4000 meters, .50BMG Ball has maximum range of 7000 meters.

i would guess a .375CT would be around 7000-10000 meters, depending on the bullet used.
 
#121
Re: .375 Cheytac questions

I have fired the SMK out of an 8 twist, accuracy was around 1 min, The 8 twist made dust out of the Rocky Mountain Gen 1. I think they made the jackets thicker on the Gen 2 but I have not fired those.

The SMK should do OK out of a 9 twist, the GS 414 will most likely tumble. The only way to know for sure is to shoot them.
 
#122
Re: .375 Cheytac questions

Thanks Augustus

I can possible get a 1:9 twist on my rifle instead of the original planned 1:10. I just wanted to here if anyone had any experience with the 1:9 twist.

Augustus what about solids, have you shot like a 350 grain from that 1:8 twist barrel you`ve got?
 
#123
Re: .375 Cheytac questions

I fired some of the CE 350 gr from the 8 twist. They were stable but accuracy was not spectacular. This particular barrel has not performed all that well with anything so no conclusions should be drawn.
 
#125
Re: .375 Cheytac questions

As far as the 375 CT goes. I have been shooting 350 gr predators, with a .050 jump out of a 1:10 twist. They are shooting 1/2 moa. I think that the 1:10 twist is the way to go. I know opinions will vary, but my barrel has shot every thing that I want it to.
 
#126
Re: .375 Cheytac questions

Steve,

I can see the reasoning behind staying with a slower twist if the objective is to maintain compatibility with jacketed bullets. Are you seeing a problem with Predators in rates faster than 1: 10" ?
 
#127
Re: .375 Cheytac questions

It seems like not to many has gone for the 1:9 twist. I also know from what i have read online is that 1:10 is a very good choice for most bullets up to the cutting edge 377 gr, including the jacket bullets.

If i had been living in usa i would have taken some chances, but it is to much trouble to get the firearm over the dam, and if the barrel is not really any good for anything, would be a real downer.
 
#130
Re: .375 Cheytac questions

Stephen,

Just like the Predators, none of the other solids are negatively effected by higher spin-rates than are required for stability.

The myth of "failure to track" begins to apply at the launch angles typically used in artillery... not small arms, and the imbalances that might be exaggerated simply do not show up in machined projectiles.

The "many" scenario is best served at the tight end of the twist range... at least in 375 where solids dominate.
 
#131
Re: .375 Cheytac questions

These are out of a 1-10.5 375 Cheytac First group is 3 shots 370 grain RMB second speaks for itself. These are at 100 yrd will post some longer range targets as I have some available. We will be testing some Predators here in a couple of weeks will post results. We will also be testing a 24 3/4 inch short rifle these were 30 inch barrel.We are currently running 2950fps out of the short barrel with 350 SMK's.

DSCF0118.jpg

DSCF0221.jpg
 
#132
Re: .375 Cheytac questions

Mtnhntr,

One thing everybody agrees upon, that has used precision turned monolithic solids, is that accuracy is incredible within their range/stability envelope.

I look forward to your reporting.
 
#133
Re: .375 Cheytac questions

The only sure thing is a sure shot. The only way to find out the performance is send it down range but regardless of my determination every rifle is different. So we'll see what works best for it and maybe it will be reference for someone else.
 
#134
Re: .375 Cheytac questions

Noel C

It is not any restrictions to get barrels and bullets in to norway, but the main difficulty is to get it out of the usa.

It is export papers out of the usa, it is both expensive and takes a really long time, once i got the barrel in my hands you can almost trippel the cost of a barrel compared to your prices in the states.

Bullets are not that bad, i think they will add something like 10% extra from the bullet dealer. All firearms parts over 100 us dollars requiers expensive paperwork, along with a long waiting time.
 
#138
Re: .375 Cheytac questions

Excaliber, The 425s are .010 off the lands if I go any deeper I the band will be in the neck. I don't think it would be good to do that. I could trim the necks back and seat them deeper if needed but they shoot nice where they are so I called it good.
 
#139
Re: .375 Cheytac questions

I fired one Rd at 2055 yds just at dark this evening. Aiming point was 12 in white circle one steel. Rd struck in edge of white at 7 o'clock. Darkness fell so I didn't fire any more. It was only one Rd so I will fire more later. I think I will go to 2500 on the next session. This load was 140 gr BMG and tha 425CE at 2820 fps.
 
#141
Re: .375 Cheytac questions

How much neck tension do any of you guys use using .350 gr smk.. Also, what is good to measure OAL.. I use hornady OAL gauge for .308. Is that ok to use with the .375 too.. Are any of you using something different?? Thanks...
 
#142
Re: .375 Cheytac questions

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: RunemHot</div><div class="ubbcode-body">How much neck tension do any of you guys use using .350 gr smk.. Also, what is good to measure OAL.. I use hornady OAL gauge for .308. Is that ok to use with the .375 too.. Are any of you using something different?? Thanks... </div></div>

I'm still a work in progress unfortunately (laid off some weeks back) but I bought a Digital Headspace Guage to try to do this as per attached link.

http://www.larrywillis.com/OAL.html
 
#147
Re: .375 Cheytac questions

Gentlemen,
I have a 375 Cheytac chambered 29 inch Krieger 1-10 barrel set to a Stillers 408 action. I have purchased several hundred 350 SMK's, (150) 377gr Cutting Edge, and a couple hundred Jamison 350gr projectiles. I am reading here that BMG powder is good to start with load development. I also have several pounds of Reloader 25 and several pounds of Retumbo. There is a lot of older threads here stating loads but I think some of this information is dated. I am open to suggestions on loads to start with. Thanks in advance for any information.
 
#148
Re: .375 Cheytac questions

Crosshairs6,
I would start with the RL 25, 128 gr up to 132 gr. This will build pressure fast, but you should find the accuracy node in this range. The velocity should be around 3000 fps or better. Stay away from the Retumbo. It is a great powder in cases that are a little smaller, (i.e. Lapua or RUM) it is not consistant on ignition with the larger cases. Good shooting.
 
#149
Re: .375 Cheytac questions

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Stephen Damron</div><div class="ubbcode-body">Crosshairs6,
I would start with the RL 25, 128 gr up to 132 gr. This will build pressure fast, but you should find the accuracy node in this range. The velocity should be around 3000 fps or better. Stay away from the Retumbo. It is a great powder in cases that are a little smaller, (i.e. Lapua or RUM) it is not consistant on ignition with the larger cases. Good shooting. </div></div>

Haha, "not mocking you at all" but I found the exact opposite.

Hangfires with R-25 and temp sensitivity.

Warm to hot loads with Retumbo worked great, less temp sensitive and way better load density. With the 375CT load density seemed to make a big difference with good ignition.

Never tried H50BMG. I read it's the go to powder for the 338CT's

 
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