375 cheytac loads?

J

jrs66vette

Sergeant
Full Member
Minuteman
Nov 16, 2008
132
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Kalifornia
#1
By chance do any of you 375ct shooters have any load data for the 375ct using 350smk? I've be looking all over the net, can only find max load of 139gr of retumbo for 350gr smk (Jamison factory load). Doing load development last Sat. I started at 133.5gr and increased .5gr per load test,when I got to 135.0 grs= 3240fps average, no pressure signs but I tought this was fast? Lawton action, lawton barrel 1/12 twist at 28". Anyhow we back the retumbo back to 132grs to shoot a 1000yd match on Sunday but couldn't check vel. seem to shoot OK. (196/200)
Going back out next weekend for more load development anybody got any suggestions?
 
#2
Re: 375 cheytac loads?

jrs66vette,

You are on the right track. You are getting plenty of velocity, and you can use either Retumbo or RL25. I prefer Retumbo, but you could try the RL25 to see if it changes your accuracy. You will not get quite the range with the SMK as you will with the Jamison 350 gr. solid, but that bullet is more expensive, and it doesn't sound like your barrel is set up for them. Rocky Mountain Bullets makes some higher BC bullets you could try also, you can get them directly from Lawton. There may be some new banded solid .375 bullets available soon too, so you have far more options than just a couple of years ago.

If you are over 3000 fps, I would look to find the accuracy node, and not worry too much about top velocity, especially with the SMK bullets.

You are doing everything OK. Just keep tweeking it, and don't worry about absolute max velocity.

My rifle is configured to shoot the 350 Jamison solids, but I have 500 SMK's sitting here too, so post us your findings.

Scott Nye
 
#3
Re: 375 cheytac loads?

jrs66vette

It's great that youre rifle shoots the 350smk good, I have tried reloader-25 and retumbo with the 350 grain smk, and I also, have tried the 330 leighs, again having horrible accuracy out of my rifle.I belive that its due to the lost river bore dimensions that I have. However it does shoot the 350grn solids sub-moa.I would be courious to see how your rifle shoots the solids when you try them let me know how they shoot.
 
#4
Re: 375 cheytac loads?

Mine is a 30" 11.5 twist Lawton and it shoots both very well. I run 127 gr RL25 with the Hooker 350 gr bullet that runs 3050 fps and 130 gr. RL25 for the 350 gr SMK's both on Jamison brass.SMK's are super accurate but fly like the 300 gr SMK,when they're done they're done.
 
#5
Re: 375 cheytac loads?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: paul2atlo8</div><div class="ubbcode-body">jrs66vette

It's great that youre rifle shoots the 350smk good, I have tried reloader-25 and retumbo with the 350 grain smk, and I also, have tried the 330 leighs, again having horrible accuracy out of my rifle.I belive that its due to the lost river bore dimensions that I have. However it does shoot the 350grn solids sub-moa.I would be courious to see how your rifle shoots the solids when you try them let me know how they shoot. </div></div>

I found with my 375CT that I had to seat the lehigh 330's way!!! out to get them to shoot good.The first groove in the projo is just off the lands by .010.

Lehigh on left Hooker on right.

DSC00131.jpg
 
#7
Re: 375 cheytac loads?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Fotis</div><div class="ubbcode-body">Is it common for the 11.5:1 LRB bore to not like 350 SMK or other "non solid" bullets? </div></div>

There seems to be mixed results out there.

Both mine and my friends 375's with LRB's absolutly hated the 350SMk's! 6"-7" groups at 300Y.I shot groups about the same size at 1000Y with the Hookers and Lehigh's.

Steve
 
#9
Re: 375 cheytac loads?

Guys, I've got another 1000yd match at the end of March. Will post loads and pics of groups. The other variable is I'm using Bertam brass, found that the neck wall measure .012 thick where Jamison measure .015, had to get neck sizing bushing die from CH4D. What is everyone using for a bullet seater?
 
#10
Re: 375 cheytac loads?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: DebosDave</div><div class="ubbcode-body">Is anyone having good luck with the 350 SMKs? I am wondering if the 12 twist might be a good answer?

Dave </div></div>

We will see shortly. I have 12.5-12 gain twist bartlein and a few smk to throw. I may work on a pointing die also. These meplats are horrible.

Jason
 
#11
Re: 375 cheytac loads?

I phoned Lawton Machine this week to see when an 8000 action would be available(not for a long time),one of the guys in the shop shots the 408/375 with a 1/11.5" twist barrel-and only shoots the 350SMK. If you have the Lost River Bore he stated the 350SMK was inconsistent.
 
#12
Re: 375 cheytac loads?

Ive had pretty ggod results from the Rocky Mountain bullets. Will know more when it warms up some but we have been shooting them at 1400 yards with a velocity of 3150 using the Retumbo at 132 grains
 
#13
Re: 375 cheytac loads?

Just broke into a new case of them yesterday. Froze my ass off waiting for a coyote to stick his head out but ended up shooting at frozen cow pies between 2000 to a little over 2400 yards. They shoot better than I do!
 
#14
Re: 375 cheytac loads?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Trgrman</div><div class="ubbcode-body">Just broke into a new case of them yesterday. Froze my ass off waiting for a coyote to stick his head out but ended up shooting at frozen cow pies between 2000 to a little over 2400 yards. They shoot better than I do! </div></div>

2 cool!
 
#15
Re: 375 cheytac loads?

I have a few questions regarding loads for the .375CT...

has anyone tried H50BMG in their 375 CT?
How does H50BMG compare to retumbo in this chambering?
Which is most likely to produce the lowest ES from a 34in barrel using the 350gr SMK`s?
 
#16
Re: 375 cheytac loads?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: groper</div><div class="ubbcode-body">I have a few questions regarding loads for the .375CT...

has anyone tried H50BMG in their 375 CT?
How does H50BMG compare to retumbo in this chambering?
Which is most likely to produce the lowest ES from a 34in barrel using the 350gr SMK`s?

</div></div>

groper,
The BMG50 is a bit too slow burning for the 350gn and lighter bullets. I got erratic groups when testing it. The best i have found is the Retumbo. Around 135gns, keep the vel under 3200 in this chamber. The upper loads have way too much chamber pressure for the barrel tennon size, there have been reports of stressed barrel thread tennons using the top loads.

350gn SMK bullets like to be seated either just off the lands by .010 or touching. I found this especially true in the Lost River bore barrels. (cheytac bore) I have built quite a few of these rifles and all of them shot well under .5 moa using the SMK bullets. Most were with the 11.5 Lawton or Benchmark barrels. I have used a 12 twist barrel as well and it is also a sub .5 moa rifle.

You have to remember the cheytac barrels have larger bore diameters and this will let you increase your powder charges to get higher velocitys, but your chamber pressure is way high when doing this. Standard barrel dimentions are easier to feel when your topped off on load pressures and the speeds are a little slower. The 375 Cheytac was designed for 3000fps shooting and the 350gn solids.

Dave
 
#20
Re: 375 cheytac loads?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 110len</div><div class="ubbcode-body">Anybody ever try VV N170?
Len </div></div>


Yes, I use 126.5 grs of VV N 170 with a 355 grs GSC in a 34" Border with a 8" twist. I must have approximatively 3000 fps at the muzzle. I've had good results up to 1420 meters for the moment.
Wish to test a heavier bullet now.
 
#22
Re: 375 cheytac loads?

If you order an action from Lawton Beware he took my money for a gun he had built and then sold it to someone else after getting my money. I have only gotten half of my money back and he keeps promisimg me an action for the ballance and still nothing in over a year. He is a thief and thats the way it is.
 
#24
Re: 375 cheytac loads?

I ordered my 375 Cheytac build last December and received it a few weeks ago without and problems or issues. They had to wait to get the bottom metal and mags but it was well worth the wait. It is a sharp looking rifle. Just have to have patience with these companys that have a ton of orders. Now as soon as they send me my die set I can see how good it sends the copper down range. As long as I do my part and the rifle shoots well I have nothing but good words to say about Lawton Machine.
 
#25
Re: 375 cheytac loads?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ViperACR</div><div class="ubbcode-body">If you order an action from Lawton Beware he took my money for a gun he had built and then sold it to someone else after getting my money. I have only gotten half of my money back and he keeps promisimg me an action for the ballance and still nothing in over a year. He is a thief and thats the way it is. </div></div>

ViperACR - been trying to PM you - your inbox is full.
 
#26
Re: 375 cheytac loads?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ARMECA</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 110len</div><div class="ubbcode-body">Anybody ever try VV N170?
Len </div></div>


Yes, I use 126.5 grs of VV N 170 with a 355 grs GSC in a 34" Border with a 8" twist. I must have approximatively 3000 fps at the muzzle. I've had good results up to 1420 meters for the moment.
Wish to test a heavier bullet now. </div></div>

Have you tried to use N570? I am planning to use that with both 355 grn and 414 grn SP GSC.

Cheers,

Master Diver
 
#28
Re: 375 cheytac loads?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Master Diver</div><div class="ubbcode-body">
Have you tried to use N570? I am planning to use that with both 355 grn and 414 grn SP GSC.

Cheers,

Master Diver </div></div>


No, I've not used it for the moment. But when the 414 GSC will be available, I'll try it without a doubt !
 
#29
Re: 375 cheytac loads?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Sotexhunter</div><div class="ubbcode-body">I will need some of this information when mine is done. </div></div>

That's what I'm thinking. LOL.
 
#32
Re: 375 cheytac loads?

did some load tesing and found my load very happy with the 370 g. rocky's at 100 yards and the 350 smk all retumbo powder all .015" jump,
was wanting a little more speed with the 370

370 RM 4.225" oal
132g 3060
133g 3072
134g 3085 best group ragged hole
135g 3092 also very good
136g 3116

350 SMK 4.185" oal
137g 3204 best group
138g 3250
 
#34
Re: 375 cheytac loads?

i will when i get home, no worries.

Im having some issues of my own, apparently the reamer used to chamber my rifle has a tight .404 neck diameter. When i loaded up a round using the jaimeson brass, my neck OD was .403in . This is not enough clearance to be safe so now i have to neck turn all my brass.

What chamber neck diameters do you guys have? And do any of you neck turn for your 375CT?
 
#35
Re: 375 cheytac loads?

Reamer print says .410

Twice fired brass measures .408

Loaded round .403

My lot of two star Jamison stamped brass neck wall thickness varies from .0133 to .0147....or so.

I don't neck turn the 375 Cheytac....yet?

No pressure problems as of yet. A Lapua Improved of mine needed .0015 radial/.003 total neck clearance to realize it's full velocity potential, and avoid pressure problems associated with insufficient clearance in tight neck chambers.
 
#36
Re: 375 cheytac loads?

ok my OAL with a 350gr SMK is 4.125 @ lands.

The meplats are pretty inconsistant tho, i measure to ogive normally.

Ive neck turned my brass down, the neck dia of a loaded round is now .401 so i have .003 clearance. Fist time doing this ive noticed how inconsistant the neck wall are, anything upto .002 with the jaimeson brass, most were alot better than that tho. With all the trouble to get your chamber and bolt face square only to indroduce runout with your brass seems like a waste of time... ill be neck turning all my brass for all my LR rifles from now so i know its true.

ill have some range data in the next couple days...
 
#37
Re: 375 cheytac loads?

ok worked up from 132gr - 134gr retumbo...

132gr groups were pretty ugly, didnt even bother measuring.
133gr was better around 1MOA.
134gr was quite good @ 0.3 MOA.

Next trip im gonna keep going up, 135gr-137gr, i have a feeling it will be best somwhere around 134-135gr.

All were fired with 350gr SMK seated .010 off lands from 34in barrel, jaimeson cases neck turned for .003 neck clearance, .004 headspace, OAL 4.115. I might neck turn my cases a tad more as i could reseat a bullet in the fired brass without sizing.

The 350SMK`s were a little inconsistant also, they had upto .010 variation in base - ogive length. Sorting them would be recommended.


 
#38
Re: 375 cheytac loads?

played with the seating depths today, the bullet likes to be close to the lands is all i can say. all groups were nice @lands and @.010 off, until the bullets were .020 off the lands and the groups went to shit.

Also had the chrony out aswell. 135gr AR 2225 (retumbo)= 3194 - 3246fps, poor ES so back to the powder measure i go...

next outing will be ladder test @ 900yds.

 
#39
Re: 375 cheytac loads?

Groper,,,can you explaine the ladder test to me...I have an 8 twist for my 375 snipe tac and I need to work up some loads...

thanks
zman
 
#40
Re: 375 cheytac loads?

Here ya go mate, explains it perfectly...

http://www.6mmbr.com/laddertest.html

Turns out my chrony was telling me lies... the ladder test worked out great, only 2 inches of vertical @ 900yds with the same load the chrony was telling me had 60fps ES... im only gonna use this cheap chrony for an average velocity indication, and nothing else from now on... wish i had an oheler 35p
frown.gif
 
#47
Re: 375 cheytac loads?

Right after the shot show Jamison listed them or $2.72 ea. but now they have them listed again for .99 ea I am going to call Monday and check for sure.
 
#48
Re: 375 cheytac loads?

You guys can either expect Seirra themselves to release a 350gr version (but will have to change something on it) or you can expect that jacketed projectile they built per a customers design and say so go AWAY completely. Only time will tell.....

Thanks
 
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