RRA LAR-8 Varmint 26"

MarshalTex

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Hey guys, i'm new here, been shooting since I was little, reloding for a couple of years and am just getting into the long range business.

So I just bought this .308. I love it is shooting 1/2 MOA at 100yrds no problem. However, I am having some casing issues with my load.

Load: 168grn a-max, 43.8 grns of 4064, 2.800" OAL, CCI BR2 Primers.

Avg Velocity: 2808
SD: 7.1
ES:15

Problem: Head on casing is getting damage from ejector, and sometimes primer is getting kicked out of casing.

Spoke with my local class 3 dealer and he said that maybe my load was too hot, or I needed a bigger gas tube. His idea was that the bolt was kicking to early, thus creating too much pressure on the eject. I like this load I think that it is going to be a thousand yard keeper, but I dont like the messed up casing and I really dont want to tear my rifle up. Lemme know what you think.
 

FCS

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Re: RRA LAR-8 Varmint 26"

Mod gas block so you can reduce amount of gas used to cycle bolt or buy an adjustable gas block.

What brass are you using?
 

hrfunk

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Re: RRA LAR-8 Varmint 26"

My Hornady manual shows the max load for a 168 gr. bullet is 42.2 grains. Interestingly, the IMR book and the Lyman manual both list top end loads of 4064 at (+/-) 45.0 grains. It could be that the Amax has a longer bearing surface that increases friction and raises pressure levels as the bullet passes through the bore. I note that your velocity is about 200 fps faster than what I usually see with a 24" 700P using 41.5 grains of 4064. That too suggests to me that your pressures are running high. The damaged case head and "blown" primers are classic signs of high pressure. You might want to try backing your powder charge down a bit. If the problem goes away and your accuracy remains within acceptable parameters, the your problem is solved.

HRF
 

Steelhead

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Re: RRA LAR-8 Varmint 26"

I would agree, your load is way too hot. Normal velocity for 168gr match ammo is around 2600 fps. You're 200 fps over that. I would definately reduce your load.

My LAR-8 Varmint loves the 180 gr Nosler's. Here's my load, please work up to it in your rifle if you wish to try it.

Winchester Case
Fed 210M primer
Nosler 180 gr. Ballistic Tip
RL-15 42.5 gr.
AVG. = 2624 FPS
SD: 15 FPS
ES: 39 FPS

DSC_0106.jpg


Here's a picture of both of my LAR-8's. The one in the background is the 16" mid-length.

DSC_0263.jpg
 

jwb47

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Re: RRA LAR-8 Varmint 26"

you dont have gas system problems .the problem is your reloads , either the components or how they are assembled. you are showing signs of an over charged load plus the velocity numbers you are showing are higher than the numbers from a 24 inch test barrel firing a compressed load with a charge of 2 grains higher than your load. check your case capacity and check your scale one more thing you may check the length of the bullet against something like a sierra match king to see if the bullet is seating to deep.;
 

MarshalTex

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Re: RRA LAR-8 Varmint 26"

I'm gonna drop the pwdr weight, see if that gives me a cure. I think that the better bullet speed may be because of the 26" barrel? correct me if i'm wrong, but it seem the longer the cake stays in the oven the hotter its gonna be
whistle.gif
,,O and i am using winchester brass. Thanks for the replies guys.
 

alongshot50

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Re: RRA LAR-8 Varmint 26"

BE CARFUL!!! I had a "good" load doing same thing...back half of a case came apart and ruined a sweet M1A stock and didnt damage the actual rifle metal parts but spread the mag out as big a tennis ball...just think what would be in side an AR platform...
 

Steelhead

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Re: RRA LAR-8 Varmint 26"

I think the suggestion to check your scale is a good one. You've got something wrong somewhere.

The longer barrel will make a difference in speed, but you shouldn't be blowing primers and getting extractor marks.

A gas-gun will generally have less velocity than a bolt gun. For example the load I use in my 20" barreled bolt gun is around 2700 fps. When I put that same load in my 16" gas-gun, it it 2350-2400 fps. Yes the 4" difference in barrel length plays a role, but not 300 fps.
 

hrfunk

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Re: RRA LAR-8 Varmint 26"

Exactly. Your longer barrel most likely accounts for some of the velocity increase, but not 200 fps worth.

HRF
 

MarshalTex

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Re: RRA LAR-8 Varmint 26"

My scale is a RCBS Range Master, so i don't that there is any problem there. I always calibrate it before I start loading. Im going to try some loads tonight at 43grns and see what happens. Ill let yall know
 

Steelhead

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Re: RRA LAR-8 Varmint 26"

Definately overpressure!

I would say back off 1.5 grains and work up from there.
 

BCP

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    Re: RRA LAR-8 Varmint 26"

    RP = remington (that is an R-P on the head right I can't see too clearly in the pics) so volume will be less than winchester and pressure will come sooner. My RP brass hit pressure about .5-1 grains before winchester did. It was pretty close to what I was able to get out of LC brass.
     

    monolithman

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    Re: RRA LAR-8 Varmint 26"

    And try second scale to make sure -- and be careful.
     

    MarshalTex

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    Re: RRA LAR-8 Varmint 26"

    Well I dropped my charge by .8 grns to 43 grns. Casing issues seemed to have dissapeared. Still some heavy scratching on the case head but nothing like it was. Heres my 2-5 shot groups+1 cold bore @ prone. The one with the caliper is my second group @ .5" after a scope adjustment. The first one was .611" and as you can see the cold bore shot to the right. Tell me what ya think.
    halfingroup.jpg
     

    MarshalTex

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    Re: RRA LAR-8 Varmint 26"

    Oh yeah this was @ 125yrds. And I think this speaks pretty well for the RRA guns as being pretty dern accurate LOL
     

    hrfunk

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    Re: RRA LAR-8 Varmint 26"

    I think you worked it out quite well. Good shooting by the way!