ATRS Modern hunter specs, pics and range reports

[Rstjean]

Here's a picture of my two modern hunters.

[UR2X3M4ME]

Noice...

Good thing comes in pair.

[556tar21]

Okay quick trip to the range for a load work up. It was only -3 but I wasn't dressed for it and was fighting a shiver the whole time.
Atrs mh 20"
4.5-14 mark 4 scope
6.5 creed
140 hornady bthp
42grains of h4350


Stickers are 3/4" and I'm owning the 2 fliers on the second target. I think these rifles are good to go
She didn't like the eldm tho

[cr5]

Has anyone done handloads for their 6.5cm with 129gr projectiles? I'm thinking of starting with Hybrid 100V since I don't have most of the powders listed in my books and Varget looks like it makes too much pressure based on the limited velocity shown. Thinking a little slower powder may help in the semi.

I'll figure out the attachments and get pics up soon. for some reason when I try to add pics it asks for a URL rather than letting me upload like I usually do on the main boards. I don't use a host site (paid membership so photo's are easier).

[cr5]

So I did a little load testing yesterday and with Hornady 129gr SST projectiles over Hybrid 100V starting at 41gr and working up to 42.1gr all rounds cycled but I could tell that the 41gr loads were pretty light. Accuracy looks promising with pretty much all 3 round groups being around 2 moa with 2 of the 3 almost touching and one dragging it out further. 41.8gr looked good with a 1 moa group with 2 of the shots going into one hole but when I made 3 more of them it was a 2 moa group evenly spaced. I.m thinking the light rain may have been effecting my groupings so I packed it in for the day and will try again next days off. So far so good though with the handloads, 100% reliable and worst groups around 2 moa.

My original 15 shots with the rifle were with 129gr Superformance and I had 2 FTF (bolt over cartridge) that bent the cartridges making them un-useable and produced around 3 moa groups, I may have been able to do a little better considering those were my first shots with the rifle and I wan't used to the trigger but accuracy with those rounds was not impressive. I saved 5 rounds for next time I have the Chrony out.

Just a re-cap. Rifle is MH in 6.5 Creedmoor with Proof carbon barrel.
I also decided to swap in the JP silent captured buffer system and installed it with the heavy spring. Next time out I'll see how it cycles with the new spring rate and adjust if needed.

[clg]

I tried running superformance with my .308 MH, stopped after 5 rounds after they all showed signs of being overpressured. Perhaps that's causing the action to cycle too fast?

[Uisge]

I believe the superperformance isn't reccomended for our rifles, very hot stuff. I want to see someone drop a couple bucks on some noveske ammo and run it. If no one else has when my barrel is installed I will run some. It's expensive but supposedly loaded for similar platforms. I'll grab a box of 110's and 168's (gonna hurt, not cheap at all! But the brass is pretty rad) and try my best to shoot properly lol!

[cr5]

I tried running superformance with my .308 MH, stopped after 5 rounds after they all showed signs of being overpressured. Perhaps that's causing the action to cycle too fast?

That's why I used Hybrid 100V, try a slower burn rate and start light. Why I also switched now to the captured buffer with the heavy spring in it. If it quits cycling I'll know it's the buffer and I'll try a lighter spring.
I should have mentioned that the 41gr loads were sooty around the neck but it cleaned up as the powder charge increased and was fairly clean with no pressure signs by the time I got to 42.1gr. Next session I'll try to remember to set up the chrony and continue working upwards slowly till I find a load that shoots or I see pressure signs.
I'll probably try 140gr next and decide on a powder later, haven't researched those enough yet. Read an article saying not to go over 130gr in AR actions for 6.5cm, something about it being harder on the action, I'd have to find it again, figured I'd start low and see.

[ATRS Shaun]

That's why I used Hybrid 100V, try a slower burn rate and start light. Why I also switched now to the captured buffer with the heavy spring in it. If it quits cycling I'll know it's the buffer and I'll try a lighter spring.
I should have mentioned that the 41gr loads were sooty around the neck but it cleaned up as the powder charge increased and was fairly clean with no pressure signs by the time I got to 42.1gr. Next session I'll try to remember to set up the chrony and continue working upwards slowly till I find a load that shoots or I see pressure signs.
I'll probably try 140gr next and decide on a powder later, haven't researched those enough yet. Read an article saying not to go over 130gr in AR actions for 6.5cm, something about it being harder on the action, I'd have to find it again, figured I'd start low and see.

That is great, keep us all posted and let us know if there's anything we can help you with.

On my 308 I was surprised how high I had to go to reach pressure signs. Makes me really wonder what powder/blend the superformance ammo is using.

[cr5]

I tried running superformance with my .308 MH, stopped after 5 rounds after they all showed signs of being overpressured. Perhaps that's causing the action to cycle too fast?

That's a little strange since Superformance is actually a fairly slow powder. Just for comparison, according to Hodgdon burn chart Varget is #101 out of 148 powders and Superformance is #128 right next to Hodgdon H4831 and H4831SC and H1000 is #140. Where did you get your load data from and did you start low or were you using heavy projectiles and going for the upper half of the load range going for velocity?

In a 308 semi I would stick to the 165-180 grain range of projectiles and start off a little light. When loading for my M305 (full custom build with Krieger barrel) I reference the service rifle load data from my Hornady book and would do the same if my MH was in 308. With semi auto's I always start lower than normal (still above book minimum) and work up, Most loads you find in your manuals are for bolt action rifles and don't take into consideration the requirements of a gas operated rifle.

When picking a powder I look through all the options and choose based on availability (what I have at home usually) and pick a powder that lists a wide range of loads and a high max velocity as it will most likely be a powder that produces lower pressures than other powders to make the same velocity. For instance I didn't go with Varget as my first attempt because it's loads in my Hornady manual ended well below the Hybrid 100V telling me that the 100V will if loaded to the same velocity do it at a lower pressure which is easier on the rifles action and leaves more room to load for a little more velocity.

Considering I probably won't be shooting my MH beyond 600 yards most of the time I don't feel the need to go with the heaviest projectile with the lowest BC, something a little lighter that will get the job done at normal distances is more practical for me and is easier on my rifle. Once I find a good load for it with the 129gr I'll probably do some experimenting with the 140gr projectiles but this will mostly be a coyote and deer rifle with some fun out to 500 yards once in a while so I'm loading more for intended use than maximum long range ballistic performance.