AAC-SD shoots like $hit after 10 shots per range visit.

[scudzuki]

I have an AAC-SD bedded in an HS Police stock.
It's bedded because I thought that would resolve the issue I'm having, but it did not change.

Background
After first mounting the barreled action in the (donor from another Hide member) HS stock, I ran an OCW with 168 SMKs and I4895.
I also made an OCW test worth of ammo for my buddy and his Remington 700 Varmint, the one with the B&C tactical stock and the triangular barrel.
The test took 2 hours, and I shot at least 36 rounds in that time; the barrel got warm but not hot, and every charge shot better than 1 MOA, with several 3 shot groups in the .5s, and I arrived at one node I was sure of, 43.5, with the bullets seated as long as the AICS mags allow (2.88 to fed reliably).

Several times now I've taken it to 400 yards and it always disappoints, but I think I'm seeing a pattern.
I setup and verify my 100 yard zero with a few shots, then shoot a 5 shot group at 100, which are always MOA or better.
Only then do I shoot the 400 yard target, and I've yet to do better than 1.5 MOA, sometimes much worse.

If I do the same thing with my .260 (Brux M24 profile) it's pretty accurate, worst of .8 MOA (5 shots) with 4 of the shots at .5 MOA, which I think I've narrowed down to ammo runout. It will shoot round after round and the POI shifts .1 mil to the right after a while but it's very predictable.

Last weekend I shot out to 600 with the .260 and brought the AAC-SD along.
I started at 300 and was hitting a 6" round steel plate.
I tried some of my friend's MK118 rounds with the same result.
Then I moved out to 500, dialed my dope, first 2 shots were 2" low of POA but solid hits on a 10" plate, then all I could hit was the dirt.
I let Dave try 3 shots, and he was killing the berm, too, but no steel.

So it seems that after about 10 shots within a 10 minute period, the accuracy goes to $hit.
I haven't cleaned the barrel, but even when I was cleaning it spotless then firing a few foulers, it seemed to follow the same pattern.

Is this pretty typical for a barrel of this weight, or a factory barrel, or a Remington barrel, or whatever?

My goal for this rifle is just this, banging steel with 1 MOA accuracy and consistency, and maybe hunting.

I'm tempted to rebarrel the action but I've got over 4000 thousand .308 SMKs (168s, 175s, a few 180s) that I picked up out of fear of losing supply, and if I rebarrel, it will be in 6.5 SAUM or 7mm-08.
I bought the AAC-SD thinking it would be "good enough" for banging steel for an afternoon of (relatively) cheap fun, but it's not working out so far.

Joe

 

[Trigger Monkey]

Who bedded the stock? I had a rifle bedded by a gunsmith that was relatively local to me and had experience building benchrest rifles but the gun shot like shit with occasional fliers. I ended up sending the stock and barreled action to GAP to get rebedded and when it returned it shot like a house on fire.

That being said my AAC-SD is a pretty consistent 3/4 MOA shooter in an unbedded AX chassis and in talking and seeing others with AAC-SD's 1/2-3/4 MOA is pretty normal shooter and ammo dependent.

 

[scudzuki]

I bedded it with Devcon steel putty.
The result is a perfectly uniform coat with no gaps. I've done all my own work, it's not difficult for a former toolmaker.
Even so, it shot exactly the same without the bedding, torqued directly to the bedding block.
It's not unusual for me to get .5" 3 shot groups at 100 yards from a cold bore.

I can envision no dynamic or effect resulting from poor bedding job that would result in a rifle that shoots well for the first 10 shots (from cold) then goes the $hit, then shoots fine again when cold, no barrel cleaning in between, same ammo.

There are other Hide members getting poor results from an AAC-SD, in fact, I think there's an active thread right now, so I know (like all Remington 700s) they're hit or miss out of the box. What's puzzling is how it goes from having acceptable accuracy to crap accuracy.

Dave (lizard1) is a good shooter, and asking him to step in for a few shots was my way of eliminating me as the possible problem.

Joe

 

[foxC]

Mebbe the powder is temperature sensitive?

 

[scudzuki]

That is probably true with the powder I'm using.

Still, I don't chamber a round until I'm ready to shoot, so I don't see how the temperature is changing that much.

It's getting hot outside today, but I have 34 rounds to fire off so I can process all my cases at once (first firing of Lapua brass) so I will document the results, and see if it follows form.

My Redding type S dies are showing up later today so I'm hoping to reduce my ammo concentricity issues.

Joe

 

[KYS]

Not to sound like a recorder but you need to go thru the normal process of checking your torque settings on all items like:

Scope Rings
Scope base
Action bolts

Verify your scope is tracking and holding zero.

Then verify the powder you have being temp sensitive. As your chamber gets hot POI will change. A hot barrel will flex more.

Mirage can also affect your 100 yard shooting a lot. I had a custom rifle that shot like crap, or so I thought, and come to find out it was the mirage messing me up. At distance it would group super tight at 600 yards, so I kept on shooting and on a cool morning I reshot my groups to confirm zero, it was making nice tight groups.

Not to insult your bedding but it may have an unseen gap or pocket down inside the stock. Did you use actual puddy or did you mix hardener and base?

 

[Mattrmvpd]

I agree with KYS.... Something is definately off...

Might also want to give some factory match ammo a try just to rule out the reloading process all together...

Something seems to be coming loose if its grouping and then a few shots later its moving all over the place. Is is possible an action screw is loosening...????

 

[CrazyDonkey]

Is the ammo sitting in the sun while it's waiting to be fired? Since you say it is getting hot, that can also change things up for you. I notice this when I have used temp sensitive powder in Arizona during the summer when shooting at 100+ weather.

 

[scudzuki]

Is the ammo sitting in the sun while it's waiting to be fired? Since you say it is getting hot, that can also change things up for you. I notice this when I have used temp sensitive powder in Arizona during the summer when shooting at 100+ weather.

No, I'm careful to keep the ammo cases in the shade, not chamber a round until I am ready to fire, etc, but as you know, there's only so much you can do when you're fighting Mother Nature.

I'm switching back to I4895 after today's range session... not much deterioration as the day progressed, just bad (1.25 MOA) at best through 35 rounds fired.

Joe

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[scudzuki]

I agree with KYS.... Something is definately off...

Might also want to give some factory match ammo a try just to rule out the reloading process all together...

Something seems to be coming loose if its grouping and then a few shots later its moving all over the place. Is is possible an action screw is loosening...????

Action screws are torqued to 55 lbs./in.

Can't see how they're coming loose.

Joe

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[Cplski7242]

Not saying anything that hasn't already been said but KYS has a great point about the torque. If the action is not torqued evenly or to the correct spec as it heats and cools this can cause problems with both accuracy and precision.

 

[Whiskey9514]

Rebarrel it to 243 260 or 7mm-08 sell the smks and be way happier without a 308

 

[Mattrmvpd]

You know.... it could be a possible scope issue.... something COULD be loose inside the scope... Have you tried different optics on it just to rule it out?

 

[steve123]

I've probably had the worst luck with stuff going wrong with rifles of anybody here on the Hide. This thread seems like a good place to vent, LOL. Maybe something will ring a bell for you.

Fatigued titanium firing pin shaft, happened over time. I was wondering why my Jewel trigger was mushy???

2 barrels vibrated loose, happened over time.

Burned out 2 barrels. Discovered this on the same stage at the same match exactly on year apart. Sub moa first day, 2.25 moa the next. What are the chances???

Started using loctite because of rings and mounts coming loose.

Scopes broke.

Temp sensitive powders suck, can really screw up a guys dope.

Variation in burn rates of non temp sensitive powders, old load no worky.

Smoking bullets.

Edit, forgot this one, some jackass put bedding compound on my frikken recoil lug.

Can't wait for the next problem, oh joy.

 

[scudzuki]

20 MOA rail is bedded, pinned with 1/8" stainless dowel pins, and fastened with 8-40 screws with Loctite.
Seekins rings properly torqued holding a March 3-24, nothing loose.
Action screws have been checked.
No voids in the bedding, bedded with 2 part Devcon steel putty; the 2 parts were weighed with a lab balance, and setup hard as a rock.
Barrel is tight.
Ammo is not left in the sun, rounds are not left in the hot chamber.
Ran it today with a different scope and different rings (Bushnell 6-24x50 FFP in Vortex rings) scope torqued to 18 in./lbs. and rail to 50 in./lbs.

Groups opened up in the 90 degree heat, 1.25" average. Didn't start out tight then open up, just sucked consistently. About 20 degrees hotter than when I developed this load.

Plenty of mirage, I turned down the magnification to deal with it, but not during a group, ran the same magnification all the way through each group to rule out reticle shift.

I'm going to try 175s and H414 next.

I guess if it consistently shot well it would be boring.

Joe

 

[mark5pt56]

I just picked up a used AAC and it shoots FGMM 175 at 3/4, even 1/2 if I'm on. I tried some 4064 and it was horrible. Also tried some other reloads from another 700 and it was sliding in under an inch. When I say horrible, like you describe here. I agree-try another powder, for some reason it simply doesn't like it.

 

[Niles Coyote]

Scudzuki, is this a new rifle? Reason I ask is if you know the round count. My 243 was throwing patterns after about 400 rounds much like you are advising here. While I am an advocate of not cleaning a barrel very often and almost never on a 308 bore I am wondering if its shot out or in need of a good copper cleaning. I cant say I have ever experienced a 308 bore exhibit the same behavior but it may be worth a look. A change in powder brand is also a good idea if you have that option, Varget and H4895 have been good in my R700 20" tactical and 26" Varmint.

 

[hahco]

I'm going to try 175s and H414 next.

I can't imagine that H414 is gonna do anything good in terms of temp stability. I've usually seen a bigger difference changing bullets than changing powders.

FWIW, a couple of my rifles are giving me fits in this heat too.

 

[scudzuki]

I can't imagine that H414 is gonna do anything good in terms of temp stability. I've usually seen a bigger difference changing bullets than changing powders.

FWIW, a couple of my rifles are giving me fits in this heat too.

Agreed, I need some Varget!
H414 shows really good velocity in the book data with the 175s, though.

Joe

 

[scudzuki]

Scudzuki, is this a new rifle? Reason I ask is if you know the round count. My 243 was throwing patterns after about 400 rounds much like you are advising here. While I am an advocate of not cleaning a barrel very often and almost never on a 308 bore I am wondering if its shot out or in need of a good copper cleaning. I cant say I have ever experienced a 308 bore exhibit the same behavior but it may be worth a look. A change in powder brand is also a good idea if you have that option, Varget and H4895 have been good in my R700 20" tactical and 26" Varmint.

Round count is pretty close to 400 right now, but I cleaned the barrel a few times at the beginning, first with carb cleaner and KG12, next time with Hoppes #9 and Sweets 7.62. Not convinced which is the best so I'm still experimenting. I use a bore guide, patches, a plastic jag, and a carbon fiber cleaning rod, no brushes. I tried a brass jag but wit the Sweets you get false positives (blue in the patches) from the brass jag.

I got the feeling I was over cleaning so it's been at least 150 rounds since I cleaned it. I guess I'll clean the bore and try again.

I do have 1 lb. of Varget but I wanted to wait until I found more before I do any development; no use finding a great load for a powder I can't get.
I'd like to switch from I4895 to H4895 (temp stability) but it's nearly impossible to find right now, and I have 12 lbs. of I4895.

Joe

 

[wrhunter]

Have you checked to see if your factory recoil lug is clocked correctly. I've heard of factory Remingtons being off a bit. Though you would have probably noticed it during the bedding process. Also do yourself a favor and check the scope base screws just to eliminate it. I just took my AAC-SD apart for a rebuild and the rear two screws were basically hand tight. This was after torquing them to spec with blue loc-tite.

 

[kamaswing]

Im telling sometimes this gun can just be a lemon! My father owned one and loaded everything you could think of to try and get it to shoot. Some groups were as big as five inches! Yes five! at 100. We just ended up selling the POS. I wouldn't recommend keeping it. Drop it like its hot.

 

[crumpett]

First thing that I thought of after reading the original post was of a rifle I had that would do pretty much the same thing. Mine would shoot awesome for about 7 rounds and then go to shit. Long story short turned out to be a spot in the barrel fouling excessively. My cure was to clean it spotless and then fired 5 fire lapping rounds through it. Just a thought.

 

[Niles Coyote]

I got the feeling I was over cleaning so it's been at least 150 rounds since I cleaned it. I guess I'll clean the bore and try again.

I wouldn't bother cleaning it then... 150 is nothing for a 308 barrel. When you get started with varget the loads I have found in my Factory Remington chambers are 43-43.4 and 44.5-45 with 175 smks. With 168's amax I have been using 45.8 the lower node should be 1-1.5 grain lower. This is with Winchester brass, for Lapua reduce by a couple tenths.

 

[Niles Coyote]

I got the feeling I was over cleaning so it's been at least 150 rounds since I cleaned it. I guess I'll clean the bore and try again.

I wouldn't bother cleaning it then... 150 is nothing for a 308 barrel. When you get started with varget the loads I have found in my Factory Remington chambers are 43-43.4 and 44.5-45 with 175 smks. With 168's amax I have been using 45.8 the lower node should be 1-1.5 grain lower. This is with Winchester brass, for Lapua reduce by a couple tenths.

 

[jmontgomery]

I bought a AAC-SD and i had the same problem.I checked to make sure everything was tight and went out and bought some hornady 168grn match it helped but still couldn't dial it in.I bought some varget and some nosler 180grn balistic tips and bam it shot good not great but good.Since i have been reloading for it i haven't found a round that shoots great.I tried different powder bullets,brass and primers and messed with the seating depth.My resolution was to send it off to a smith and have it gone thru new barrel action work and a new stock.I am sure it will be a different monster when i get it back.My thoughts on this rifle were it was based to basically just run a can hince AAC and the heavy 1/10 twist 20'' barrel.I originally bought mine to just run subsonic but the HIDE convinced me other wise lol.

 

[JGorski]

Here we go again, a guy reports his 700 isn't shooting and the replies are "your bedding is off", "powder is sensitive", yada yada. First thing I noticed is your oal, 2.88", thought everyone knew that these bullets and many others in the 308 like to be around 2.8-2.85" and no more. So, trying adjusting your seating depth down to 2.8 and see what happens.

 

[JGorski]

Agreed, I need some Varget!
H414 shows really good velocity in the book data with the 175s, though.

Joe

Joe, if you want great velocity from 175-178 get some 2000MR and load up 47.3-47.5grs of it, again, seat your bullet no more than 2.85", I seat the 178 HPBT to 2.830" for my sporter 308 and it shoots pretty good. And my velocity is 2723, this was shot at 200yds. using a 6X scope. Bottom rifle in 2nd pic.

 

[Niles Coyote]

This,

First thing I noticed is your oal, 2.88", thought everyone knew that these bullets and many others in the 308 like to be around 2.8-2.85" and no more. So, trying adjusting your seating depth down to 2.8 and see what happens.

I some how missed that...

2.815-2.83 is where I am at depending on which bullet and they are all internal mag box friendly... doesn't matter if I am running a AICS mag or not.

 

[scudzuki]

I didn't think SMKs liked that much of a jump, but I'll try it.

Being as the throat in this factory Remington chamber is so long that at 2.88 (max mag length) IIRC I'm .070" off the lands, I figured that's enough of a jump.

I've been watching for 2000MMR but it doesn't pop up very often like everything else these days.

WR, the recoil lug on this barreled action is pretty good and there's no interference in the stock.

I'm gonna go back to I4895 and load to COL 2.800 next.
I have plenty of bullets, primer, and powder, and I can always use more trigger time.

Thanks to all for your insights.

Joe

 

[JGorski]

In either of my 700 308s the 168AMAX is touching the lands at around 2.925"oal, I seat them at 2.825 and they've been shooting .5moa out to 300yds, last month had a 5 shot group that went 5.3"(flier was lower?) with 4 of the shots at 3.1" during out last 600yd BR comp, that was with 46.5grs CFE, last year a load of 47grs CFE I got 4.7", yeah, a mile off the lands, too.

 

[TheGerman]

This has nothing to do with the ammo I am led to believe. You said that it did perform to some extent at distance and then it goes to shit shortly after for both you and your friend.

This is either something with the optic, which is less likely because I doubt it will re-zero itself every-time after screwing with you, and I doubt it is anything with your scope rings/base torque settings for the same reason.

The common theme seems to be that it starts misbehaving once its hot. That is either the barrel itself (rifling/throat/something) or something has heated up to the point of expanding and your barrel/stock are no longer free floated. A simple test may be to try the dollar bill free float trick before you start shooting and then see if anything changes once it starts going to shit. This may have something to do with the bedding to where you are fine when cool but something warps/moves/expands once hot. I once saw that someone had bedded their action yet managed to get the barrel slightly crooked in the stock channel to where after a few shots the barrel and stock channel side would rattle together.

Additionally, check for any flex or hairlines cracks on your stock and in your stock channel.

 

[SFree]

Might wanna check the throat and chamber/bore with a bore scope to see if there are any inconsistencies, ya never know...

 

[hdbiker1]

Had the same issues with one I had. The load I finally settled on was 44.1gr Varget, Win brass, br2 primer, 175 SMK seated at 2.81 oal. But It also took over 400rnds before the rifle settled in and started shooting more consistent. Oh, I also cleaned every 50-100rnds until it hit that spot. Here was a typical group with that load.

 

[Krazyjohnny]

We have the same rifle. We have it in an AICS Chassis and that improved it greatly. We then pitched the "X-Mark POO" triger and installed a Timney 517. The trigger alone was the best $150 we have spent. We run a JP brake on it and we commonly get 3/4"-1/2" MOA at 100 yds running 175 gr SMKs riding on 44 grns of BLC-2 in Federal GMM brass. Now at 300 yds it is a different story. We get about a 9" spread. We use a comparator and the 308 case from Hornady and found that the OAL from the primer end of the case to the tip of the bullet when it was pushed into the lands was 3.0254". That is way the hell out there, especially when you consider the SAAMI spec for the length is 2.80 IIRC (don't have my book in front of me). The AICS mag is 2.90 so staying below that will net us a good feed with quite a bit of jump. Can't even get a VLD out there. So these rifles seem to be chambered really deep.

 

[scudzuki]

We have the same rifle. We have it in an AICS Chassis and that improved it greatly. We then pitched the "X-Mark POO" triger and installed a Timney 517. The trigger alone was the best $150 we have spent. We run a JP brake on it and we commonly get 3/4"-1/2" MOA at 100 yds running 175 gr SMKs riding on 44 grns of BLC-2 in Federal GMM brass. Now at 300 yds it is a different story. We get about a 9" spread. We use a comparator and the 308 case from Hornady and found that the OAL from the primer end of the case to the tip of the bullet when it was pushed into the lands was 3.0254". That is way the hell out there, especially when you consider the SAAMI spec for the length is 2.80 IIRC (don't have my book in front of me). The AICS mag is 2.90 so staying below that will net us a good feed with quite a bit of jump. Can't even get a VLD out there. So these rifles seem to be chambered really deep.

I have had exactly that experience, too.

Rifle is shooting sub MOA at 100, then 8" at 400.

Same day, my .260 shoots .6 MOA at 100 and .6 MOA at 400.

I replaced the stock trigger spring with one from Ernie the gunsmith dot com, the X Mark Pro trigger is very nice at 2 pounds now.

There's .1" gap between the barrel and the stock. No way the barrel is touching the stock.

And there's no way the scope is shifting then shifting back, as pointed out.

I did find some serious copper fouling yesterday, and finally got that barrel squeaky clean.

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[wnroscoe]

When you worked up your loads did you do it with or without the can?

Do you have any 175 SMK's or 155 Lapua Scenars?

For suppressed shooting, I had to work my ammo up suppressed, 308 Gasser and 260's, there was a .4 to .5 load difference between what shot un-suppressed vs suppressed.

Try H4895 with the 175's and Varget with the 155's. That's the way I've ran all of my 308's and the ones I've built get ran the same exact way.