DPMS LR .308 / Vortex PST Range Event

[disdp1]

Well, just got back from my vacation in MI and spent a day on the Marksmanship Training Center Rifle Range.

The best group of the event was a 4 1/8 inch 3 round group at 935 yards. First time pushing out this far with this rifle. Was
extremely happy with that group. Following group at a 1000 yards yielded one round at 4" high, 2" right, and one at 0" and 10" left w/
the 3rd round missing Left.

All groups after that were being pushed left by the rising wind. Final group of the day required 1.8 mils of windage right.

While on the range, talked to several members of the MI Rifle team and learned the range has been in existence only a short
time. Fantastic opportunity on a 1000 Yard Range just SSE of Traverse City MI. Need to contact the range to setup a time to
shoot if interested.

I've worked hard at developing a load the rifle liked. To date, eliminated powders Varget and H4831. Finally finding IMR4895 worked best.
Regarding bullets, eliminated all Nosler and Sierra rounds. Finally found the Hornady Amax at 178gr worked the best. Additionally, I
had tried Hornady 178 grn BTHP but they were all over the paper as well.

The group above was off a bipod and shooting mat so any arguments of having the rifle locked into a lead sled are irrelevant.

When I mentioned the scope to several of the guys on the MI Rifle team, they responded they had not hear of it. All I can say is I'm
extremely happy w/ the Vortex. Every rifle on the MI Rifle team had a Night Force which wasn't surprising.

Anyway, if anyone can glean some info from this post, then that's a good thing.

Regards,
David Palecek
Green Bay, WI

 

[AvsFan]

David,

That's incredible shooting my friend - Wow! Can you post some pictures of your set-up?

AvsFan

 

[GotGoodGroups]

Is your Vortex clear at 24x power? At which magnification do you have almost 0 parallax? I am guessing around 12.

 

[ARsR4ME]

Do you mind telling your reload set up to?

 

[disdp1]

One of the bad things that happened on the trip is my wife went to Sleeping Bear Dune where you can climb the 500 yrd vertical dune and she got the camera full of sand. I'm scrambling to either clean it or replace it for her trip to Peninsula State Park, WI here in 5 days.
I'd take picks of the target and the rig, but right now that's not happening. Darn spouses! (Ha)

Anyway, the rig is a DPMS LR .308 heavy SS fluted barrel w/ a Miculet muzzle brake. I put a Nightforce Unimount 20 MOA mount w/ the Vortex PST 6x24 FFP scope on it. Added a trigger kit by JP Enterprise.

Load info is 40.9 grns of IMR4895 w/ Federal Larger Caliber Primers using Hornady 178 grn Amax bullets in Lapua .308 brass. I was using Lake City brass and notice the ejection pattern was not consistent, thus the reason to move to better brass.

I had did a Ladder Test at 560 yards and it turned out that 42.7 grains had a good grouping but the velocity was 2690 fps. I did shoot that for quite some time but noticed the brass was getting ejector markings and thus too hot.
I wanted to keep the higher velocity but re-analyzing the ladder test I found that the 40.9 to 40.7 grain load was very accurate. I had the round chronograph at 2530 - 2550.

I want to push this out as well, Normally, I hunt w/ a .270 WeatherBy Mag w/ bullet speeds at 3400 fps. I missed 3 running deer this last year using the DPMS due to shooting behind them I assume. Anyone have
words of wisdom for shooting at running deer w/ a 2550 fps rifle round versus 3400 fps? Thanks!

Talking to guys on the MTC range, the majority response on velocities was around 2550.

I wish I would have had someone w/ load/rifle info to give when I was developing this rig. So having said that, I'll entertain any reasonable questions to help fellow shooters.

Regards,
David Palecek
Green Bay, WI

 

[elfster1234]

would you happen to have any pics of the event and the rifle?

 

[ARsR4ME]

My go to match load is 43 varget in sorted win brass and 175 SMK 210m primers. It does really well but im getting slight extractor marks and its only doing 2560 fps. I'll look at that powder and see if i cant get more fps from it.

 

[GlockandRoll]

Sounds like money well spent.. I'm sold on DPMS for the money, you cant beat it. I love my 6.5cm and my mk12, they are two of my favorite rigs.

 

[Luky]

A barrel length would help (to better understand what velocities you are achieving). 2560 fps out of a 16"/18" is a lot different from 2560 fps out of a 24" barrel. I get about 2666fps with 43.4gr Varget, 175 SMK and a 210m primer, winchester brass, out of a 24" barrel. This is not a "hot" load for me. But that is a Savage model 10 and I am curious if it will be that much different out of a gas gun?

 

[GlockandRoll]

isnt there a rule of thumb that you can guestimate with, using the same BBL lenth/twist rate/projectile size, between gassers and bolts?
Seems like I saw that somewhere and cant remember where...

 

[Luky]

isnt there a rule of thumb that you can guestimate with, using the same BBL lenth/twist rate/projectile size, between gassers and bolts?
Seems like I saw that somewhere and cant remember where...

I have never run into this. I know there is a rule of thumb that you get about 25 fps more velocity per inch of barrel, up to about 26" and then the increase per inch starts dropping off the longer the barrel (like 18 fps per inch from 26-30 inch and 10fps per inch beyond 30" or something). On a side note, I have also read .22 long rifle drops off after about 16" (all the powder has burned) so if you have a 18" or 20" barrel you are acually loosing velocity inside the barrel.

 

[LRRPF52]

isnt there a rule of thumb that you can guestimate with, using the same BBL lenth/twist rate/projectile size, between gassers and bolts?
Seems like I saw that somewhere and cant remember where...

The velocity rate of increase or decrease follows a curve, with a higher rate of change the shorter the barrel is. Each barrel will have its own characteristics producing velocities lower or higher than "the norm", so it's kind of hard to form a rule.

I've heard specific measurements from shooting teams, who after receiving 10 consecutive Krieger barrels for their service rifles, found that there was an extreme spread of 200fps across the lot of them using the same exact load.

In my 22" .260 gas gun, I get 24" book velocities easily that were developed in a 24" test rifle. I have heard from rifle manufacturers who shut off the gas in AR15's, and saw no measurable change in velocity from when the gas was open.

 

[ARsR4ME]

A barrel length would help (to better understand what velocities you are achieving). 2560 fps out of a 16"/18" is a lot different from 2560 fps out of a 24" barrel. I get about 2666fps with 43.4gr Varget, 175 SMK and a 210m primer, winchester brass, out of a 24" barrel. This is not a "hot" load for me. But that is a Savage model 10 and I am curious if it will be that much different out of a gas gun?

It's a stock LR so its 24". I notice a bit of a drop from bolt to gas gun.

 

[JWV]

Nice shooting! I only live a few hours from that range and still haven't made it over there. Soon hopefully.