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Sudden accuracy degradation ?

E

evilsvt

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Minuteman
Aug 4, 2005
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college station, TX
I went to the range today and with my stand by ammo, BH 168gr BTHP red box, which is normally 1/2 MOA went to sh1t. I was getting HORRIFIC horizontal stringing, like 12-13 inches worth. The gun is a GAP Crusader with a S&B PMII on it and I made sure everything was torqued, which they were. The only thing that I can think of is either bad ammo or the gun was extremely dirty.

It's been 293rds since I last cleaned it and of those 293rds, the last 150 were fired suppressed. During shooting I blew out two primers. As I started to clean the gun, I noticed that my bore guide was extremely tight going in the chamber, but after I cleaned the chamber out it went in like butter.

I'm hoping it was just because the gun was dirty and so was the chamber, any ideas?
 
Re: Sudden accuracy degradation ?

no strikes and the 12" was the initial shot. After a couple rounds it was about 6" off with the suppressor and with it off the best group I could muster was ~3"
 
Re: Sudden accuracy degradation ?

are you shooting a gemtech can? those can be a bitch on groups....and was the can on tight?
 
Re: Sudden accuracy degradation ?

it was an OPS 3rd and it was the first thing I checked. I gave it a good cleaning and it was fouled like a mother, carbon came out almost in a sludge.

I'll also pull the scope and remount it and retorque everything just to make sure.
 
Re: Sudden accuracy degradation ?

How many rounds down the barrel?

Try the same ammo now that it's clean and also try some other ammo if you have some to see if it was ammo related.

Same thing happens to my bore guide when dirty.
 
Re: Sudden accuracy degradation ?

solar flares this morning
 
Re: Sudden accuracy degradation ?

If I was you, I would want to know exactly what the heck caused the sudden change. To do that, I would not start ripping apart every component of the rig at one time.

I personally don't think your rifle got dirty and suddenly started spraying. We've seen rifles with more rounds than that shoot exceptional with no cleaning except the chamber and bolt face. While anything is possible, I vote No on the fouled excuse.

Either way, I would encourage you to check/change one thing at a time to isolate and identify what caused it. Might come in real handy in learning about the personality of your particular equipment.

Now that you cleaned the barrel and sounds like the suppressor, go shoot it. Get it hot and see what happens. I would have liked to have seen you clean the suppressor only but sounds like you're already past that point.

Everybody's gear combination has a different personality. Each setup has it's own strengths and weaknesses. It is up to us to learn what those things are and exploit the strengths while guarding the weaknesses. Anyway, good luck on getting it sorted out. I just wanted to encourage you to take a structured approach to the diagnosis so you will be more wise after the fact.
 
Re: Sudden accuracy degradation ?

Thanks y'all.

I noticed on my last outting I was getting a lot of latteral movement as well, but I thought it was just me since we were at extended distances.

I haven't pulled the scope yet so I'll get out there and shoot it now with the same ammo since it's been cleaned.

rifle has 723rds through it and only 150rds through the suppressor
 
Re: Sudden accuracy degradation ?

Terry didn't say it wasn't solar flares.
 
Re: Sudden accuracy degradation ?

very well could be, I've shot about 300rds of the same load from the same lot and just started to blow primers
 
Re: Sudden accuracy degradation ?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Captain Kick-Ass</div><div class="ubbcode-body">Terry didn't say it wasn't solar flares. </div></div>

Sky was clear on our side of the sun
cool.gif
 
Re: Sudden accuracy degradation ?

Getting pretty hot, temperature wise, near Bryan, Tx this time of year eh? Were your loads showing any pressure signs before? Not like this will cause your change of impact, but it might be the cause of your primers blowing. Keep your ammo in the sun? In a black case? Might find one of the little insulated lunch bags or just keep the rounds out of the sun...

As to the shift of impact; scope, bases, rings seem most likely culprits, or maybe your suppressor torque value being wildly off?

Got a boresighting collimator? Check your scope's movements.
Use an inch pound torque wrench and check all your base & ring screw values. I've used a Bushnell 74-3333 bore sighter and a craftsman click-over ip torque wrench for 15 yrs and recommend a boresighter with grid table to check your scope movements and zero, and an IP torque wrench to eliminate variables in your fastening systems.

Might also check your action screws and barrel to receiver fit. Who knows? 45-65 IP for the action screws, and your barrel should be tight.
 
Re: Sudden accuracy degradation ?

If it doesn't get any better after cleaning and everything is torqued as it should then I would try to change scope with a scope that I know for sure there is no problem with and try shooting some groups

Good Luck
 
Re: Sudden accuracy degradation ?

I was just looking back through my logbook from 21 years ago. There was a particular day that I had crazy, stupid horizontal stringing. Just couldn't figure it out.

According to my notes on the 2nd page of that shooting session, Sgt Bob Veblefester (Ret. Civil War Veteran and 139 yrs old at the time) pulled out his Farmers Almanac and after a few minutes of reading, mumbled "Thought so". He looked up at me from his wheelchair and said "Solar Flares. Nothing you could have done about it Sonny." He showed me the page in the Almanac and it said these cycles happen every 21 years or so.

Really. No shit. It's in my logbook.
 
Re: Sudden accuracy degradation ?

here is the deal.....ya cleaned your can right......but how do you know there was NOT a bullet strike ????....

these can be very subtle things....manifesting themselves with just a crease making a showing at the exit hole......almost could look like a seam of a weld....but of course it is just the whole length of the bullet rubbing past and disturbing the path enough to fly in a prescribed direction.....also the gun may have a 'ring' to it when .....when you listen for it.....
 
Re: Sudden accuracy degradation ?

I would say that it was dirty. You have got to clean more often when running a suppressor than when not.

I swab out my AR about every 500 or so when I am shooting suppressed. Now granted its a gas gun and does foul a little more but I would think that a suppressed bolt gun is gonna foul even greater in a faster manner than without.
 
Re: Sudden accuracy degradation ?

Have you tried different ammo yet?

As far as I know, centerfire rifle suppressors do not need cleaning hence why most manufacturers seal them.
 
Re: Sudden accuracy degradation ?

I used to have a savage that would shoot 1/2moa without fail, and it would do the same when it was dirty.

However when I did a basic cleaning (no copper cleaner etc.) the cold bore shot would be 14" low every time, without fail. I would have to clean it at the range and then run a fouling shot through it before I put it away in order to have it be allright to hunt with. I just quit cleaning it after a while and it shot great ever since.

My point is, scrub the rifle till your knuckles bleed and see what happens after that. it could just be a dirty rifle.
 
Re: Sudden accuracy degradation ?

In my suppressed rifles, if I switch between sub-snoic and full power loads, I have to clean the bore or I will have pressure issues .... severe ones.
 
Re: Sudden accuracy degradation ?

evil,

Have you taken your bolt apart? Maybe you have some primer cup material (from your blown primers) in the FP channel that is messing with the consistent ignition/burn of the powder. Try cleaning our the bolt real good and see if that helps.
 
Re: Sudden accuracy degradation ?

With the confirmation of Terry Cross, (if it is in the log book it's official) I'm going to have to agree with Captain Kick Ass here.... A phenomenon of nature my friend.
 
Re: Sudden accuracy degradation ?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: patches</div><div class="ubbcode-body">With the confirmation of Terry Cross, (if it is in the log book it's official) I'm going to have to agree with Captain Kick Ass here.... A phenomenon of nature my friend. </div></div>

ya all drink from the same beer bottle too......it don't mean its a freak of nature like yourselves.......
 
Re: Sudden accuracy degradation ?

IF I were to doubt my logbook and the Civil War Vet, I would prolly want to check out the suppressor setup per BoltRipper.

Shoot it for groups with and without the can. That will immediately get the suppressor out of the equation one way or another.

It's a sad, sad day Scott when I start seeing you doubt the experience of a 139 year old combat vet.

 
Re: Sudden accuracy degradation ?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Captain Kick-Ass</div><div class="ubbcode-body">solar flares this morning </div></div>

That's why able to send the moon rocket?

Oxymron of NASA*3

Last missions problem still not fixed!

I really don't want that kind of memory of the third one blowing up!
 
Re: Sudden accuracy degradation ?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TCA4570</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Captain Kick-Ass</div><div class="ubbcode-body">solar flares this morning </div></div>

That's why able to send the moon rocket?

Oxymron of NASA*3

Last missions problem still not fixed!

I really don't want that kind of memory of the third one blowing up! </div></div>

drinks are served at 4pm in Ohio
 
Re: Sudden accuracy degradation ?

I have seen a few lots of Black Hills ammo than ran extremley hot for some reason. I've seen gas guns blow several BH primers.
Check a few of this lot of ammo in another rifle if you can. Just one more variable to eliminate.
Rob
 
Re: Sudden accuracy degradation ?

I had similiar issues from my 30-06 at the last range trip. Groups were opening up and stringing horizontally. Albeit it was only about 3-3.5" at 200y so I passed it off as wind at first because it was pretty breezy that day. As soon as you described your situation my thought was "dirty...oh...wait.. OH! Go home and clean your own rifle you lazy bum."

I foamed it with wipeout last night and pushed a few patches through this morning before leaving for work. It was bright blue and there was a sizable amount of black fouling that came out with it. Definitely needed cleaning, it's been probably 500-600 rounds since the last cleaning but a lot of that was with "plinker" ammo and surplus powder which runs pretty dirty. I foamed it once more before I left, anything else should come out quickly tonight when I get home.

Good luck with the culprit if it's not the dirt doing it. As everyone else advised, check one thing at a time, pick a point at one end of the rifle and work to the opposite end. Since you already cleaned it, next thing I'd try it taking the suppressor off, then check the action screws being tight, then the scope, then the trigger, etc. etc.
 
Re: Sudden accuracy degradation ?

I experienced a similar thing with my 300 Win recently. 3 round groups (this was before I knew better) went from sub half MOA to 4.5 MOA in a matter of 66 rounds. Happened over a time frame of 18 months. We tried cleaning the bore with every method known to man. Also disassembled and re-torqued everything twice. The solution I finally found, and one that I highly recommend, was to sell the rifle and build another.
 
Re: Sudden accuracy degradation ?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: cavemanmoore</div><div class="ubbcode-body">... The solution I finally found, and one that I highly recommend, was to sell the rifle and build another. </div></div>

Quitter...
 
Re: Sudden accuracy degradation ?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bohem</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: cavemanmoore</div><div class="ubbcode-body">... The solution I finally found, and one that I highly recommend, was to sell the rifle and build another. </div></div>

Quitter... </div></div>

Was that an insult or a compliment? Because it made me feel bad, but I laughed out loud while doing it.
 
Re: Sudden accuracy degradation ?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: cavemanmoore</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bohem</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: cavemanmoore</div><div class="ubbcode-body">... The solution I finally found, and one that I highly recommend, was to sell the rifle and build another. </div></div>

Quitter... </div></div>

Was that an insult or a compliment? Because it made me feel bad, but I laughed out loud while doing it. </div></div>

Nah, it was a joke. Although at the expense of selling something and not understanding what was broken doesn't make sense to me. For a car or some other vehicle it makes sense to just let it go, but I've never seen a rifle that can't be fully dimensioned, torqued and understood. Some take little effort, some you feel like you're pissing up a rope and then all of the sudden it clicks.
 
Re: Sudden accuracy degradation ?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bohem</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: cavemanmoore</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bohem</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: cavemanmoore</div><div class="ubbcode-body">... The solution I finally found, and one that I highly recommend, was to sell the rifle and build another. </div></div>

Quitter... </div></div>

Was that an insult or a compliment? Because it made me feel bad, but I laughed out loud while doing it. </div></div>

Nah, it was a joke. Although at the expense of selling something and not understanding what was broken doesn't make sense to me. For a car or some other vehicle it makes sense to just let it go, but I've never seen a rifle that can't be fully dimensioned, torqued and understood. Some take little effort, some you feel like you're pissing up a rope and then all of the sudden it clicks. </div></div>

I like this, "the expense of selling something and not understanding what was broken doesn't make sense". I'm storing that one for use on myself later!

The replacement rifle is an extension of who I am. When she goes wrong I will go to great lengths to correct her. The problem rifle was more like the neighbors kids. When they screw up, I send them to someone who cares enough to spend the time. It's more amicable for everyone that way.

Evil, any luck?
 
Re: Sudden accuracy degradation ?

havent had a chance to get to the range yet with work getting in the way
frown.gif



I'm going to try and make it out there tomorrow and if not, it'll be sunday at earliest
frown.gif
 
Re: Sudden accuracy degradation ?

It turned out that I over torqued the ring/base screws when I moved the scope the other day.
 
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