390 grain Hornady A-Tip load development 375 Cheytac

[secondofangle2]

I loaded up 5 each of 124 126 and 128 grains of vv n570 in junk Jamison grass; got 2925, 2975ish and 3015 fps with those all with SD less than 7; accuracy was kind of all over the place in a 1-10 twist Lilja barrel, 35"; pockets were loose to start with, starting to get ejector swipes at the 128 grain load but bolt lift easy.

COAL was 4.350" (IIRC) which is about 20 thousandths off the lands; Fed 215m primer

I then loaded up 5 each of 125, 127, 129 in Bertram brass. The 129 and maybe the 127 grain started opening up the pockets but no hard bolt lift, no bright ejector swipes; accuracy was even worse for this round in a 1-12 twist Bartlein barrel, 35". Like the first 3 shots through a freshly cleaned barrel went in a horizontal line marching to the left by 2 MOA each shot - I have no idea what to make of this. The remainder of the groups were 1.5+ MOA 5-shot groups which is NOT characteristic for this (or the Lilja barrel). Fortunately I had some 350 SMK loads (132 grain vv N570, about 3200 fps) with me that I know shoot lights out with both barrels and ran 3 through the Lilja barrel (all touching, about 3/8" CTC) and 2 through the Bartlein (touching, 1/4" CTC), so I know it's not me flinching and it's not the barrels.

I'm not sure what to do next, but I think I'm going to load some up with RL50 because I have that and it sinks 750 AMAX into one hole with my Lilja 50 BMG barrel.

My other observation is that the loss of 200-250 fps with the 390 gr bullet compared to the 350 SMK at 3200 (132 grains n570) and 352 grain CEB (3220 fps with 134 grains n570) all but wipes out the gains from the improved BC in terms of drop, but leaves it a little edge still for wind drift. I'm inclined to persist because I don't like solids and we're trying to develop a long range deer hunting round.

I have plenty of Peterson brass but intentionally started with less sturdy stock to detect pressure signs earlier. I wager that Peterson will be able to tolerate just shy of 130 grains n570 before it starts to give in to the pressure. I will report more results when available; please also share your own experience and thoughts below. Thanks!

SOA

 

[M77]

What rig is this in ? HTI?

 

[White Death]

May need faster twist like 1:8

 

[secondofangle2]

What rig is this in ? HTI?

Yes it’s an HTI. Hornady recommends 1:11 but the calculators suggest 1:12 ought to be fine

 

[secondofangle2]

It's looking like my barrel(s) like RL33 & RL50 more than N570 which is a relief b/c availability. One thing I do know is that the upper limit (in my barrels) are in terms of pressure:

N570 127.5 grains ~ 3000 fps
RL33 134 grains ~ 3060 fps in 34" barrel
RL50 140 grains ~ 3080 fps in 34" barrel

QL, which doesn't have data for this bullet yet says these are all at the same pressure, so it's consistent with known burn rates. I used the SMK as a base bullet, upped the weight to 390 and made a ballpark assumption based on bullet geometry comparison that using the hornady is like loading the SMK about 0.250" deeper.

Currently loaded at about the lands.

I hope this helps somebody else developing this load. I called Hornady and they said they have no data/experience yet.

 

[secondofangle2]

Compressed load of vv 20n29 at 142 grains is also below pressure.

It's looking like they like a "jump" of about 100 thousandths in my gun. Went from 1 thou off to 25 to 50 to 100 and groups got better with each increment.

My 50 BMG likes the AMAX at 250 thou off so this should not be a huge surprise, but it kinda was.

 

[secondofangle2]

Confirmed. In my barrels, a 100 thousandths (0.100") "jump" is the way to go with 138 of RL50; COAL 4.250; velocity 2960 SD 2.8, ES 7.0 5 shots today 0.576 MOA at 110 yards. Second such group in a row (first was 3 shot group at exactly 1/4 MOA last week, same load). NO pressure with this load, could go higher, but why?

For the record also, I shot 3 with 136 vv 20n29 today; SD was 5.8, velocity 2760 average. I think that powder is too big to put enough in to get the velocity; I have some loaded to 140 and 142 that I shot at an earlier session but did not chrono them. Accuracy is not as good as RL50 either so I'm tabling this load.

 

[MarcC11B]

And this is a standard Cheytac (if there is such a thing)? I have been playing with these in a Snipetac with a 36” barrel. Haven’t ran it hard, a middle of the pack load of 139gr of RL50 in Peterson brass gets 2960 fps average. The 100 yard groups (3shot) were really good in the K&P barrel, however the ES reading from the Labradar sucked and the subsequent 1500 yard groups showed it. Maybe running it a little harder will improve this, also gonna try H50BMG as I just found a decent supply of it locally.
I also found that the deeper into the case I seated the bullet, the better the groups got.

 

[secondofangle2]

thank you MarcC for reporting these observations confirming mine. AFAIK this is the only thread out there on 390 load development and this information will be immensely helpful for others developing this load and for the two of us comparing notes (even though as you note, I'm a standard cheytac and you're a snipetac).

 

[secondofangle2]

I have confirmed repeatedly that 0.100" off is where these like to be, and also they like 138 grains RL50 in Bertram Brass for 2960 fps and superb accuracy, no pressure, and low SDs and vertical spread at range.

I then switched to Peterson Brass. With 138 grains, that led to a spike in velocity to 3000-3010 with early pressure signs and more erratic SDs. Almost assuredly a result of a couple of grains less case capacity with Peterson.

So I backed off to 136 in Peterson and BINGO, I'm back down to 2960 with SD 5 fps in a 34-35" barrel (forget which).

I checked them at range today and 2 weeks ago. This is interesting. TRASOL cannot map these bullets at 1 mile. It thinks they need way more elevation gain than they do, like 2-3 MOA at 1760 yards. Only way I could get TRASOL to predict flight was to up the BC to .508 or up the velocity to stupid numbers which were inconsistent with LABRADAR; no other inputs were in error or could explain it. I wonder if there's a typo in the algorithms in TRASOL.

Applied Ballistics, however, with the "custom drag curve" (that I purchased) or the G7 BC of .465, aligns PERFECTLY with my 1750 yard target.

Today, I took my son out shooting in the west desert with his first gun (he's 2.75 years old) and sneaked off to fire 10 shots at the 8" plate at 1160 yards. Again AB was spot on with elevation first shot, and vertical dispersion was minimal with a bullet travelling 2960 from a 35ish" barrel 1:12 twist. I am somewhat confident that will be the sweet spot with this bullet, unless somebody brings a H50BMG or US869 load to the table that beats my RL50 load (I have not tried either - H50BMG is erratic in availability and US869 can usually be beat with RL50; if my observations are generalizable, Hornady changed from 869 to RL50 in the past 5 years).

SOA out.

 

[NightStash]

I have confirmed repeatedly that 0.100" off is where these like to be, and also they like 138 grains RL50 in Bertram Brass for 2960 fps and superb accuracy, no pressure, and low SDs and vertical spread at range.

I then switched to Peterson Brass. With 138 grains, that led to a spike in velocity to 3000-3010 with early pressure signs and more erratic SDs. Almost assuredly a result of a couple of grains less case capacity with Peterson.

So I backed off to 136 in Peterson and BINGO, I'm back down to 2960 with SD 5 fps in a 34-35" barrel (forget which).

I checked them at range today and 2 weeks ago. This is interesting. TRASOL cannot map these bullets at 1 mile. It thinks they need way more elevation gain than they do, like 2-3 MOA at 1760 yards. Only way I could get TRASOL to predict flight was to up the BC to .508 or up the velocity to stupid numbers which were inconsistent with LABRADAR; no other inputs were in error or could explain it. I wonder if there's a typo in the algorithms in TRASOL.

Applied Ballistics, however, with the "custom drag curve" (that I purchased) or the G7 BC of .465, aligns PERFECTLY with my 1750 yard target.

Today, I took my son out shooting in the west desert with his first gun (he's 2.75 years old) and sneaked off to fire 10 shots at the 8" plate at 1160 yards. Again AB was spot on with elevation first shot, and vertical dispersion was minimal with a bullet travelling 2960 from a 35ish" barrel 1:12 twist. I am somewhat confident that will be the sweet spot with this bullet, unless somebody brings a H50BMG or US869 load to the table that beats my RL50 load (I have not tried either - H50BMG is erratic in availability and US869 can usually be beat with RL50; if my observations are generalizable, Hornady changed from 869 to RL50 in the past 5 years).

SOA out.

I have been testing that bullet for awhile now and also shoot them around 2960 in both rifles using H50bmg with great results. The AB custom curves are also from both my rifles with the only difference being barrel twist. It has produced great results out to two miles.

 

[secondofangle2]

I have been testing that bullet for awhile now and also shoot them around 2960 in both rifles using H50bmg with great results. The AB custom curves are also from both my rifles with the only difference being barrel twist. It has produced great results out to two miles.

What’s your barrel length?

 

[NightStash]

What’s your barrel length?

36” 1-8 and 1-10 twist

 

[aauya]

I have been testing that bullet for awhile now and also shoot them around 2960 in both rifles using H50bmg with great results. The AB custom curves are also from both my rifles with the only difference being barrel twist. It has produced great results out to two miles.

what was your load with H-50 BMG

 

[secondofangle2]

Enough H50BMG to get 2960 fps and not a grain more or less LOL

 

[MarcC11B]

Played with H50BMG a bit yesterday, 143gr in the Snipetac got 3030 fps and close to .25” @ 100 yards for 3. When playing with powder charge the 4 shots I sent (starting 140 & 143 final) made a very nice little cluster. I loaded a few more up with 143 grains and made a first round impact at 1240 yards and followed it up with 2 more that read about .6 moa in the reticle. Was getting dark on us so that was the stopping point. Gonna try to take it out to 2000 yards sometime in the next week or so. Christmas and then a Christmas deer season are upon us, but that 1240 plate is sitting about 10 feet from a feeder…and there were deer there last night.

 

[BCX]

Any update at shooting deer at 1240 yards w the 375?

 

[MarcC11B]

Unfortunately no deer showed up the one afternoon I got to sit out there. It was only a 3 day season, so someone else will have to be the guinea pig.

 

[Geno C.]

Played with H50BMG a bit yesterday, 143gr in the Snipetac got 3030 fps and close to .25” @ 100 yards for 3. When playing with powder charge the 4 shots I sent (starting 140 & 143 final) made a very nice little cluster. I loaded a few more up with 143 grains and made a first round impact at 1240 yards and followed it up with 2 more that read about .6 moa in the reticle. Was getting dark on us so that was the stopping point. Gonna try to take it out to 2000 yards sometime in the next week or so. Christmas and then a Christmas deer season are upon us, but that 1240 plate is sitting about 10 feet from a feeder…and there were deer there last night.

What brass are you using?

 

[MarcC11B]

Peterson in that barrel. My original load (for hunting, 375 grain Chinchaga @ 3150) I use Bertram, it’s used in my 30” (10” twist) Bartlein.
Fired the ATip load a few days back. Last 3 shot group made a nice triangular 7” group @ almost 1300 yards and an SD of 9 for the last 10 rounds fired. Still haven’t gotten to the 2000 yard range. In a couple weeks I may be able to really stretch it out.

 

[LastShot300]

I checked them at range today and 2 weeks ago. This is interesting. TRASOL cannot map these bullets at 1 mile. It thinks they need way more elevation gain than they do, like 2-3 MOA at 1760 yards. Only way I could get TRASOL to predict flight was to up the BC to .508 or up the velocity to stupid numbers which were inconsistent with LABRADAR; no other inputs were in error or could explain it. I wonder if there's a typo in the algorithms in TRASOL.

Applied Ballistics, however, with the "custom drag curve" (that I purchased) or the G7 BC of .465, aligns PERFECTLY with my 1750 yard target.

SOA out.

Looks more like a problem with the data. Hornady states 0.497 G7 for this bullet, so TRASOL with the nominal DC 0.5 requires a tad bit more up to 0.508. Clearly AB tested the bullet and also found a discrepancy with Hornady's data and lowered the number to 0.465 in order to align the planets.

 

[MarcC11B]

Clearly AB tested the bullet and also found a discrepancy with Hornady's data and lowered the number to 0.465 in order to align the planets.

I am running the BC @ .460 G7, at least it’s good to know that I wasn’t really off. I was doubting my findings, but haven’t really pushed it to the trans range either.

 

[LastShot300]

I am running the BC @ .460 G7, at least it’s good to know that I wasn’t really off. I was doubting my findings, but haven’t really pushed it to the trans range either.

Indeed TRASOL required less tweaking to the Hornady's value of 0.497 (0.011 variation from 0.508) vs the AB (??) value of 0.465 (0.032 variation)

 

[secondofangle2]

Thanks Last Shot for bringing this up. For the life of me when I tested that day at 1760 I could not get TRASOL and AB to give the same solution but AB got me on the target. After your reply this AM I plugged in the Hornady advertised .497 G7 into TRASOL and the custom curve into AB and made sure everything else the same and got the exact same solution at 1760 and indeed to 2400 just plugging in random distances. INterestingly, for a DA of 5000 in both but temp 30 in AB and temp 59 in TRASOL, that made a .2 MRAD difference at 2400 yards. I did not know that the same DA could give very slightly different results with the same DA but different temperature.

So I may just go back to TRASOL.

One thing TRASOL is missing is a powder temperature correction. Other than that it is waaaay more user friendly than AB in almost every conceivable way.

One thing I HATE about AB is that it changes the wind direction when you sync the weather, and it's NEVER correct. That is a really really stupid feature to build into the app given the supreme importance of wind. The last thing I want it doing is changing the wind direction or speed that I have manually entered. I do however want to update the temperature and baro periodically as the day goes on. There are several other things that I may make a thread about in the proper forum.

Again thanks for pointing out that something was going wrong that day. I do suspect that it was something stupid that either AB or TRASOL or yours truly was doing with the inputs/atmospherics.

SOA2

 

[LastShot300]

Thanks Last Shot for bringing this up. For the life of me when I tested that day at 1760 I could not get TRASOL and AB to give the same solution but AB got me on the target. After your reply this AM I plugged in the Hornady advertised .497 G7 into TRASOL and the custom curve into AB and made sure everything else the same and got the exact same solution at 1760 and indeed to 2400 just plugging in random distances. INterestingly, for a DA of 5000 in both but temp 30 in AB and temp 59 in TRASOL, that made a .2 MRAD difference at 2400 yards. I did not know that the same DA could give very slightly different results with the same DA but different temperature.

So I may just go back to TRASOL.

One thing TRASOL is missing is a powder temperature correction. Other than that it is waaaay more user friendly than AB in almost every conceivable way.

One thing I HATE about AB is that it changes the wind direction when you sync the weather, and it's NEVER correct. That is a really really stupid feature to build into the app given the supreme importance of wind. The last thing I want it doing is changing the wind direction or speed that I have manually entered. I do however want to update the temperature and baro periodically as the day goes on. There are several other things that I may make a thread about in the proper forum.

Again thanks for pointing out that something was going wrong that day. I do suspect that it was something stupid that either AB or TRASOL or yours truly was doing with the inputs/atmospherics.

SOA2

You welcome! Something odd is the variation in dope given the same DA but with different temps. That should not happen at all., unless the temp is used to adjust the MV given the air temp. You know, the program will set only on one specific way to compensate atmospherics. AB doesn't like DA because it messes with the Mach number, which is not an issue with Trasol (or Coldbore if you want the fully fledged solution with temp correction and a lot of other truly advanced functions and features)

 

[Axel314]

U have any trouble with the 390 a tips in the 8 twist?

 

[MarcC11B]

I haven’t, just shot it out past 2500 and it did great.

 

[Geno C.]

I’ve got 160 of these showing up today and hoping to make them work for the Spearpoint match this next weekend. Been having a hell of a time with some solids for some reason. Hope these are going to cooperate. George Gardner suggested that we don’t take them over 2950 in the 8 twist.

 

[ARKEMAXUS]

I’ve got 160 of these showing up today and hoping to make them work for the Spearpoint match this next weekend. Been having a hell of a time with some solids for some reason. Hope these are going to cooperate. George Gardner suggested that we don’t take them over 2950 in the 8 twist.

I was getting ready to order some 400 grain Flatlines but I keep hearing about guys having problems with getting a good load with solids so I'm starting to think about the A-tips. Interested to hear your results.

 

[Geno C.]

I’ve got a couple things yet to try but running out of time. Figure the atips will be easy enough to get to shoot well

 

[Geno C.]

133.3 H50bmg in mine with a .100” jump is just under 2800fps

133.4 in @Jamie C is 2850 while forming. We’ll run this at Spearpoint this weekend. Should have everything formed by then. Waiting on an answer from hornady about when they’ll make another run of them before I commit

 

[Taylorbok]

133.3 H50bmg in mine with a .100” jump is just under 2800fps

133.4 in @Jamie C is 2850 while forming. We’ll run this at Spearpoint this weekend. Should have everything formed by then. Waiting on an answer from hornady about when they’ll make another run of them before I commit

Let us know what hornady says. I'm waiting on some also

 

[Taylorbok]

Does anyone have a bullet they could measure for me. I am trying to have a reamer set up. I just need to know the length of the bearing surface. The distance from the boat tail junction to the ogive. Much appreciated

 

[secondofangle2]

Does anyone have a bullet they could measure for me. I am trying to have a reamer set up. I just need to know the length of the bearing surface. The distance from the boat tail junction to the ogive. Much appreciated View attachment 7838941

About 0.575" I just measured one

 

[Taylorbok]

Ok sorry another question. It seems most of you guys are saying these bullets like 0.100" jump. I am assuming you all have a fairly long free bore to accommodate that, do you have decent accuracy with the solids jumping them what I'm assuming is .250-.300?

reason I ask, I want to shoot these hornady bullets but haven't been able to get my hands on them yet and from what I have found its no problem to order up say some WTC flatlines and have them in a couple weeks.

 

[secondofangle2]

My chamber is the "regular" cheytac chamber but with the one exception of the freebore. I forget if it's 150 thou of freebore or 150 thou *more* freebore than the drawings on the Peterson cartridge website. (BTW can anybody tell me which measurement on this drawing represents the freebore? https://vertassets.blob.core.window...7c-4837-9f62-ce16bb6fc15d/_375__9_5_x_77_.pdf)

I never shot solids in this barrel, and whenever I did shoot them in other barrels, it was 352 CEB loaded to the driving band. I've always had the same chamber cut from the same smith in SLC UT area who uses a DT reamer.

I have shot about 300 of the A-tips, and have another 500 on hand that I got a couple of months back for about $34 per box at shooting surplus. Looks like they shipped directly from one of the distributors, Bill Hicks

 

[Taylorbok]

My chamber is the "regular" cheytac chamber but with the one exception of the freebore. I forget if it's 150 thou of freebore or 150 thou *more* freebore than the drawings on the Peterson cartridge website. (BTW can anybody tell me which measurement on this drawing represents the freebore? https://vertassets.blob.core.window...7c-4837-9f62-ce16bb6fc15d/_375__9_5_x_77_.pdf)

I never shot solids in this barrel, and whenever I did shoot them in other barrels, it was 352 CEB loaded to the driving band. I've always had the same chamber cut from the same smith in SLC UT area who uses a DT reamer.

I have shot about 300 of the A-tips, and have another 500 on hand that I got a couple of months back for about $34 per box at shooting surplus. Looks like they shipped directly from one of the distributors, Bill Hicks

That's a pretty janky diagram to read but the freebore is S - L3= 3.86mm which is approx 0.150" so I'm guessing that is what you have.
that being said I am assuming you have the boat tail below the neck shoulder junction to be able to jump them 0.100"

 

[disky1]

.375 A-tips back in stock at various usa dealers.

Anyone want to send me like 40 boxes to canada?

 

[secondofangle2]

cheapest here where I got mine

Hornady 3729 A-Tip Match 375 Cal .375 390 GR A-Tip Match 25 Per Box

Hornady 3729 A-Tip Match 375 CAL .375 390 GR A-Tip Match 100 PER BOX

shootingsurplus.com

 

[232593]

It's looking like my barrel(s) like RL33 & RL50 more than N570 which is a relief b/c availability. One thing I do know is that the upper limit (in my barrels) are in terms of pressure:

N570 127.5 grains ~ 3000 fps
RL33 134 grains ~ 3060 fps in 34" barrel
RL50 140 grains ~ 3080 fps in 34" barrel

QL, which doesn't have data for this bullet yet says these are all at the same pressure, so it's consistent with known burn rates. I used the SMK as a base bullet, upped the weight to 390 and made a ballpark assumption based on bullet geometry comparison that using the hornady is like loading the SMK about 0.250" deeper.

Currently loaded at about the lands.

I hope this helps somebody else developing this load. I called Hornady and they said they have no data/experience yet.

Thank you for all the data you posted. It was of great assistance in safely developing my .375 CT load with RL 50 and the ATIPs.

I still have not been able to hit that 2960 velocity yet. Always above or below, but I’m working on it.

Thanks again for posting this.

 

[Taylorbok]

Thank you for all the data you posted. It was of great assistance in safely developing my .375 CT load with RL 50 and the ATIPs.

I still have not been able to hit that 2960 velocity yet. Always above or below, but I’m working on it.

Thanks again for posting this.

Why do you have a target of 2960? if it shoots good above or below that pick which ever node better suits your situation and stick with it.

 

[232593]

Why do you have a target of 2960? if it shoots good above or below that pick which ever node better suits your situation and stick with it.

With 138 grains of RL50 at .070 off the lands the best I can get is an ES of 13 FPS. And an average velocity of 2990. At 137 grains I would have had an ES of 8FPS but had a flyer and an average velocity of 2980. And 136 & 136.5 gave me average velocity of 2947 each.

From what I have observed with both .408s I have is certain bullets like certain velocites. Both rifles perform best at 2850ish with a 420 grain RMB. So that said, if @secondofangle2 says 2960 with a desert tech HTI (which is what I have) I will try to see if I can get that speed.

But you bring up a good point, maybe I should test the 137 grain load again and see if I just had a flier last time?

 

[232593]

Peterson in that barrel. My original load (for hunting, 375 grain Chinchaga @ 3150) I use Bertram, it’s used in my 30” (10” twist) Bartlein.
Fired the ATip load a few days back. Last 3 shot group made a nice triangular 7” group @ almost 1300 yards and an SD of 9 for the last 10 rounds fired. Still haven’t gotten to the 2000 yard range. In a couple weeks I may be able to really stretch it out.

What G7 or G1 BC do you use for the 375 grain Chinchaga bullets? Do you use RL50 as well? I don’t mean to derail the thread but I can’t find any posted numbers for them.

 

[MarcC11B]

What G7 or G1 BC do you use for the 375 grain Chinchaga bullets? Do you use RL50 as well? I don’t mean to derail the thread but I can’t find any posted numbers for them.

I’m using .8 G1, and 155 grains of RL50 (.375 Snipetac).

 

[secondofangle2]

My barrel is a 34” Bartlein not a DT barrel

 

[232593]

Well if I can get over this COVID crap I’m going to go to the range tomorrow and try my 137 grains of RL50 390 grain load and do a pressure test with the 375 grain Chinchagas starting with 130 grains of RL50 and going to 140 grains or so.

Thanks for all the info posted here.

 

[BCX]

These A-Tips couldn’t handle a SG of 4.05 today

 

[Geno C.]

What twist?

 

[BCX]

Not my rifle, it was a Cadex Shadow w 1-7. When they held together, they shot.

 

[secondofangle2]

Excessive twist is a fool’s pursuit. I know u said not your rifle. But in general