438 rounds and accuracy is gone????

[acemisser]

heavy bull barrel 1 in 9 twist Mc Gowin barrel same load same bullet
same primer same brass same oal same rifle action.....What once
was like a 1 3/8 group 10 shots at 250 yards is now a 3 to 4 inch
group...Will different lot of the same brand of powder (varget)
make that much of a difference? Have never had this happen be for now..:hail:

[glassbeaver]

Varget is notorious for lot to lot variance. Chrono and see what's up. If you haven't yet, run something like Montana xtreme or butch's bore shine through your barrel. That's about the round count for some copper fouling. hopps won't cut it for that.

[snowgetter1]

Sounds like a dirty barrel. What calibur is it??

[scope eye]

Hey Ace groupings don't go from 1 3/8" to 4" over night, you notice it grow 1/4 or 1/2 at a time, if you clean your barrel don't over clean it, just enough to remove some not all, and then try it again, scope mounts also come to mind.

Dean

[squirrelsniper]

Yes, a change in powder lot number can do that, although your case is toward the extreme (pardon the pun) side of things. Since powder manufacturers have a range of what they consider "normal" variation, it's common to have to tweak a powder charge to get it back to where it was. If you had a lot number at one end of the spectrum and now have a lot number that's at the other end of the spectrum, it's quite possible it could ruin your accuracy. Though I rarely use a chrono for anything, this is one place it can come in handy. If you know what velocity you were running at a given temperature, you can usually tweak the powder back to that same velocity and get your accuracy back. You may still have to tweak slightly, but getting back to the same velocity is a big step in the right direction.

Also, fouling could be at least part of the problem unless you've been cleaning regularly with a brush and strong solvents. Everyone seems to like trying the "no bronze brush" method of cleaning. With a decent barrel that will work fine for a while, but eventually you'll most likely have to do some scrubbing with a bronze brush.

[65impala]

I would check, in this order the following:

First: Clean the bore with some copper fouling remover, scrub brushes and regular cleaner can still leave copper deposits behind. I use Barnes copper cleaner, it seems to work best for me. Follow the directions, just swabs, no bruses.

Second: Check the stock screws, bedding, forearm, etc. If something has come loose, there's your problem.

Third: Check load over Chrony, what is it doing compared to what it used to do? Powder lot variations can cause problems at times. This is why I buy 8-10 pounds at a time from teh same lot. Also, check to see if the lot you has is part of a recall, it may be a problem issue.

Fourth: How is your scope? I would check and double check all scope mount/base screws and possibly swap a new scope in place just to eleminate it as an issue.

There are other things to check out, but I personally check those items when I have a sudden, unexpected loss of accuracy.

[SHL540KB308]

I have been using Varget for years and have never had more than a 2 to 3 tenths difference to get it back on line, but it still could be your powder. Bullets do change, depending on brand, without notice. If you have a box of 500 I guess that would take them out of the picture. I assume you clean your barrel, like most, usually over cleaned. Not much info contained in your post to work with.

Check your tools, check your master round and see if you get correct readings.

Later, Brad

[Russell D]

What round are you shooting? I'm building a rifle that I don't expect barrel life to be over 500 rounds...

[eddiesindian]

heavy bull barrel 1 in 9 twist Mc Gowin barrel same load same bullet
same primer same brass same oal same rifle action.....What once
was like a 1 3/8 group 10 shots at 250 yards is now a 3 to 4 inch
group...Will different lot of the same brand of powder (varget)
make that much of a difference? Have never had this happen be for now..:hail:

hope you have some rds left over from your "accurate load" cause if you do...you better chrono and see what your speed was/is.
the 3 main reasons I own/use a chronograph is 1: ck my speed once Ive found my barrels sweet spot 2:input needed for ballistic calculations for bullet drop out to distance 3: tweaking powder charge due to new lot# of propellant.

I love Varget, but Its "at times' caught me by suprise when I saw my accuracy go bad.
Ive since learned to always keep extra unfired known accurate loads handy of any given propellant along with data such that of primers/case speed/temp ect...

Its kinda hard for me to believe that youve fired that many rds thru your tube without a cleaning

[acemisser]

I read all your post and appreciate..Sorry I forgot to mention it is a 223 cal...I checked everything except running over
the chrono...Myself,I think it is the different load number of Varget...So I am going to work on the load some,by going
up and down with the load...I was using 25.0 grains with the 69 gr SMK bullets...And I clean after every 50 rounds.I use break free
and let it soak as well as Butchs bore shine...I have gotten very,very little copper out of this barrel...Scope is tight.action screws
snug,etc,etc...There is also a possibly of different lot of primer's..I know one guy that is running the same bullet and powder
only he is going 26.5 grain which is a full case....I have never like compressing loads like that...Once I get it figured out,I will repost..

[scope eye]

A 223 going south at 400 shots no way, something changed you just haven't spotted it yet.

Dean

[sab1]

If you're using the same brass over and over again, without annealing the necks, work hardened necks could be the culprit. When they work harden, they can wreak havoc with neck tension and seriously affect accuracy. If you do have repeated firings with that brass, try some new cases. It's funny, a friend just told me about this exact scenario happening to him some years back at a party last weekend...

Regards,
Scott

[eddiesindian]

I read all your post and appreciate..Sorry I forgot to mention it is a 223 cal...I checked everything except running over
the chrono...Myself,I think it is the different load number of Varget...So I am going to work on the load some,by going
up and down with the load...I was using 25.0 grains with the 69 gr SMK bullets...And I clean after every 50 rounds.I use break free
and let it soak as well as Butchs bore shine...I have gotten very,very little copper out of this barrel...Scope is tight.action screws
snug,etc,etc...There is also a possibly of different lot of primer's..I know one guy that is running the same bullet and powder
only he is going 26.5 grain which is a full case....I have never like compressing loads like that...Once I get it figured out,I will repost..

what a coinsidense...Im running 25.2 on my 69s.....be as it may, my tube is 1-8 going 2900fps.
Ive been a Varget fan for the past 15 or so yrs. It hasnt been but the last 2 years where Ive seen a change in my speeds due to a change in lot #. As a matter a fact, Im not all that happy with the last 8lb jug Im currently going thru. Way too much deviation on speeds between rds. Dont wanna giveup on Varget "yet" but Im must be honest and say that Im having an affair with RL-15 at present time and loving it.

[JW]

Acemisser

I too have had some differences in varget lots
3-4 tenths of a grain if I remember
I have also noticed a little length difference in bullet lots on the 69SMK ( bullet to lands overall length)
usually less than .005" though
My barrel is 1-8 twist and strange as it sounds, shoots well around 23.8 gr, 25.0 gr and lights out at 26.3 gr of varget
You will get it figured out
Jack

[lal357]

your load is about on par with what you will see most use one thing i noticed is you clean every 50 rounds or so why i dont clean mine until i see the groups starting to open up most go 200-300 .also are you measuring oal or ogive i have seen bullet length change on some bullets and even though the oal is the same the ogive to lands are different.

[acemisser]

If you're using the same brass over and over again, without annealing the necks, work hardened necks could be the culprit. When they work harden, they can wreak havoc with neck tension and seriously affect accuracy. If you do have repeated firings with that brass, try some new cases. It's funny, a friend just told me about this exact scenario happening to him some years back at a party last weekend...

Regards,
Scott

Scott---You may have something there..I think this was like the 4th or 5th loading....I keep note on everything but that.....So maybe I will anneal a few of them and load up a few and we will see what happens...BUT this is still a different lot number of varget...I still have 2 lbs of that lot left..Next time if possible I am going with 8 lbs...

[nubrun]

Dont wanna giveup on Varget "yet" but Im must be honest and say that Im having an affair with RL-15 at present time and loving it.

Have you noticed RL-15 being extra dirty? It seems like cleaning takes twice as long after I tried RL-15 for 10 rounds then when I shot 100 rounds using Varget.

[earl39]

RL-15 tends to be (in my experience) a powder that runs cleaner at the higher pressures and dirty burning at the lower pressures.

[savage308]

Carbon fouling,try some bore tech had the same issue with my 6br

[kelbro]

Carbon fouling,try some bore tech had the same issue with my 6br

My guess too.