Range Report 6mmAR Turbo 40D+ more

Re: 6mmAR Turbo 40D+ more


Great info thanks.

So [per Field Firing Solution] your JLK 105 load has an "Army" max effective range of right at 1000yds. and The SIE BulletSmiths would say it's good on deer to about 800. That's good numbers out of a tidy little Ar!

Thanks.
 
Re: 6mmAR Turbo 40D+ more

I'm out of R-15 now and am still debating which bullet to use.So I did another ladder test at 300 yards with AA2520 and the 105JLK's.

I don't know what to do?LOL. I had less than a half inch of vertical for 30,30.2,30.6,30.8 and 31 grains of AA2520. 30.4 hit 2 inches higher than the rest but I bet I pulled the shot. 30.2,30.6,30.8 were a .4inch group.

I guess I'll have to try for some 400 yard groups at each weight and see which does best.I sure got the seating depth right!

Steve
 
Re: 6mmAR Turbo 40D+ more

Long story short.

I kept shooting and reloading 15 pieces of brass over and over again trying to work up a new load with the AA 2520 and JLK 105's.Big mistake!!!
I started getting some horrible groups with big flyers in the 2 inch range at 100Y.I decided to inside neck ream and uniform the flash holes to no avail.I even thought my scope was busted.

The primer pockets were still tight after 17-18 reloads.

So I started again with some new brass and got .5-.8 inch groups again.

I guess that with semi auto's you just have to throw the brass away after 10 or so reloads for best accuracy.

Steve
 
Re: 6mmAR Turbo 40D+ more

10 loads seems pretty good. I have had my eye on the 6AR for a while. I see they sell Redding dies to size Grendal brass but I was wondering what youd go through starting out with 7.62x39 Win brass. It's about half the price and Win brass seems to be gtg with everything. With the Redding dies would you just have to go through the steps with different neck bushings until you get to 6mm or is there another way. I have been loading 308 for a while but nothing that needs to be modified. Thanks for any input.
 
Re: 6mmAR Turbo 40D+ more

Shepheard,

I see what you are saying but I think it's not going to be worth the extra effort involved in forming from 7.62x39.I think the Lapua brass is so good that it's worth every penny.

Just guessing but you would have to go though 3-5 steps using bushings.Then you might have to neck turn,don't know how thick the necks are?Then you still have to fire form it also. 7.62x39 has a large rifle primer and I'm not sure how well it will handle the pressures the 6.5 Grendel can.

Robert has this system (dies,chambering reamer,loads)pretty well thought out already.I'd just buy from him and your all set.

Steve
 
Re: 6mmAR Turbo 40D+ more

Hey steve123,

I'm back, I tend to disappear for months at a time
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I should have some time over the next month to get some info on my 6mmAR(non turbo) for comparison.

I have 200 cases necked down and primed along with a pile of berger, swampy and lapua 105's with a variety of powders.

Great write up; tons of information to learn from. Thanks!

shepheard,

I think in the long run you would be better of getting the lapua brass and a set of dies from Robert. It's too easy to neck the quality Lapua brass down.

468shot
 
Re: 6mmAR Turbo 40D+ more

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: steve123</div><div class="ubbcode-body">Long story short.

I kept shooting and reloading 15 pieces of brass over and over again trying to work up a new load with the AA 2520 and JLK 105's.Big mistake!!!
I started getting some horrible groups with big flyers in the 2 inch range at 100Y.I decided to inside neck ream and uniform the flash holes to no avail.I even thought my scope was busted.

The primer pockets were still tight after 17-18 reloads.

So I started again with some new brass and got .5-.8 inch groups again.

I guess that with semi auto's you just have to throw the brass away after 10 or so reloads for best accuracy.

Steve

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EDIT...I'm looking at this post now about 3 years later and realized this is about when I first started noticing accuracy problems. What ended up happening is that the barrel starting loosing from the barrel extension.
 
Re: 6mmAR Turbo 40D+ more

6mmART40 revisited.

The upper has about 1900 rounds through it now. It's been an up and down experience for me. Mostly a thumbs up.

The AA2520 powder ended up being a very temperature unstable powder. Nearly 150fps difference between summer and winter. I quit using it even though it meters better than any powder I've used.

At about the 500 round mark the barrel started coming loose from the barrel extension. It took me almost 500 rounds/3-4 months to determine what the problem was do to the barrel unscrewing "very slowly" and accuracy-POA shifts getting gradually worse. Robert Whitley fixed the problem for me.

When I got the upper back I worked up a new load. 30.2 grains of H-4895/105Amax/2.245OACL shot the best producing the lowest ES. Velocity was in the 2900 fps range and was a hot load. Every once in a while I'd get a jam with a failure to feed. The round went into the chamber most of the way but the BCG would stop at about 80% of it's travel. It was a easy jam to deal with because all I'd have to do was pull back the bolt till the hammer cocked and let it go.

Another year went by and I decided to try and fix the feeding issue by altering the magazines. I took .030 off the front of the lips where the cartridge is released, widened the lips .010 and polished the edges and releaved the area of the mag in the forward part that guides the shoulder of the case into the feed ramp. The mods helped reliability but did not eliminate them.


Recently I fireformed some new Lapua brass. After fireforming I discovered the previous load of 30.2 grains H-4895/105 Amax in conjunction with a new 8lb keg of H-4895 would not work, way to hot???

So I worked up a new load. 28.3 grains of H-4895/105Amax/2.248" shot best overall. The barrel is starting to show it's age as I'm only able to get 3/4" groups at 100Y now. The velocity has decreased to 2740 fps. The good thing is I think I stumbled onto why the rifle was jamming once in a while. I'm guessing it was because of the higher pressures of the last load (maybe the case wall grabbing the chamber too hard or gas system timing???). This new load hasn't malfunctioned at all in 300 rounds.

Good news! I finally won my first long range match with the upper using the new load last weekend after all these years, YAY!
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I had gotten three 2cnd place finishes and also some top 5's before with this upper with it giving a few hiccups but I'm much happier now that the upper is working reliably.

For the next barrel I'm thinking I'll order a reamer made to my cases and dies with zero freebore so the bullets won't have such a large jump as it does now. Also I want to have a muzzle brake put on along with getting the barrel Melonited.





 
Re: 6mmAR Turbo 40D+ more

I just stumbled on this thread. I've been shooting a 6mm Turbo 40 for a couple years now, although I haven't put nearly as many rounds through mine as you have through yours.

This is by far my favorite AR. I have a 24" Pac Nor, 1:8 twist on mine. I have used mine mostly for varmint hunting for which I have found it to be superb.

Mine shoots pretty much every bullet I have ever tried from 70gr to 107gr very well. Have tried several powders and have RL-15 and H4895 to work the best.

If you haven't tried 87gr Berger VLDS, give them a shot. I have gotten my best accuracy from these. 1/4 moa at 2938 fps (29.8gr RL15) and .3s at 3003 fps (30.7 gr RL15).
 
Re: 6mmAR Turbo 40D+ more

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: steve123</div><div class="ubbcode-body">Hi Lakeway,

How has reliability been with yours?

Looks like yours shoots great! How many rounds through it ?

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Reliability has been excellent. Only time I encountered any problem was when I failed to bump the shoulder enough when I resized the brass. This was my fault. I made a slight adjustment on my die and no more problems.

I have about 450 rounds through mine.
 
Re: 6mmAR Turbo 40D+ more

My son and I bought matching T-40I uppers from Robert and have been extremely impressed. We asked Robert for a left side charge and right side eject so we wouldn't have to get off of the rifle while prone or in an odd posistion at a match.
This is by far the most accurate gas gun I have ever shot. Both rifles like the same loads, which is just about anything, and one setup on the dies works great for both.

30uxtzt.jpg

2nalnhh.jpg

2hyavip.jpg
 
Re: 6mmAR Turbo 40D+ more

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Col Freckles</div><div class="ubbcode-body">My son and I bought matching T-40I uppers from Robert and have been extremely impressed. We asked Robert for a left side charge and right side eject so we wouldn't have to get off of the rifle while prone or in an odd posistion at a match.
This is by far the most accurate gas gun I have ever shot. Both rifles like the same loads, which is just about anything, and one setup on the dies works great for both.

30uxtzt.jpg

2nalnhh.jpg

2hyavip.jpg
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Very cool!!!

Great idea!

What load and barrel length are you guys using?
 
Re: 6mmAR Turbo 40D+ more

24" Kreiger with a Tubb brake.

Using 29.8g Re-15 behind a Hornady 105

Trying to get to the range this week to chrono a few different loads. Trying some Berger 95's and some H4895 with the 105's
 
Re: 6mmAR Turbo 40D+ more

I have a 6mm RAT which I think is the same as the turbo 40 deg.I use 29.3 gr. RL-15 and 105 Hornady 105 bthp @2850fps. 29.2 of RL-15 with 107 SMK @ 2800 fps. Out of a 27" Saturn 1/8 barrel. All are loaded to 2.28 oal in C-products mags with a slight tweek. Both have single digit SD and shoot 3/8 moa or better using Lapua brass.
 
Re: 6mmAR Turbo 40D+ more

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: toygunner</div><div class="ubbcode-body">I have a 6mm RAT which I think is the same as the turbo 40 deg.I use 29.3 gr. RL-15 and 105 Hornady 105 bthp @2850fps. 29.2 of RL-15 with 107 SMK @ 2800 fps. Out of a 27" Saturn 1/8 barrel. All are loaded to 2.28 oal in C-products mags with a slight tweek. Both have single digit SD and shoot 3/8 moa or better using Lapua brass. </div></div>

Hi toygunner,

Looks like your rifle shoots real tight.

Did you build the rifle for comps?

How has reliability been on your 6mm Rat?

What tweeking did you do to the mags?

Is the throating set up for mag length?

Thanks
 
Re: 6mmAR Turbo 40D+ more

The rifle shoots good. I was going to use it in comps, but was worried about wind (compared to my 260) In a light wind less 10 mph halfway consistent wind its a lazer out to 800-900. Heavy gusty winds make it a little tough.

The RAT is about 99% reliable. Every once and while I may have an ejection issue. Feeding is 100%.

The mags, I broke the front sharp corner of the feed lips to keep from scaring the brass so much and let the case start to pivot a little sooner as it leaves the mag. Also on each side of the follower to the front I took a little off to let the front come up more for the last round.

The throating is not set for mag length. I think 2.235 oal is needed to for the 105 HBTHP.

I really like the combo in a small frame AR. No recoil and lighter than the large frame.

Mine too has the 2" longer gas system. I made my own extra long handguard in 2" dia.It came with a WOA 2.25" . I didnt like it.

I've shot it to 1200 yards, but it hard to see hits on steel do to energy of the bullet.