What made my accuracy become horrible?

[KylerB]

Sorry that this is a long story but I feel the whole back ground to my problem is necessary.

So last year I purchased a Remington model 700 .270 win. Being new to reloading, a friend loaded a decent load for the rifle. After shooting it for a year I decided I wasn't happy with the performance of this load so I decided to develop my own load. After shooting many different loads I had a few loads getting very close to my goal of .5" at 100 yards. By this time I had fired about all my brass 3 times and they were beginning to be too long(anywhere from 5 to 15 thou long compared to spec), so I trimmed them to 5 thou under maximum spec, give or take a thou. I also dry tumbled them in walnut chips for the first time after I had fully prepped the brass. I went to the bench and and the groups that were almost .5" before were now ugly 2-3" groups.

Was it the trimming of the cases that caused the bad accuracy or was it some thing to do with the tumbling such as residue left in the brass?

Any help is appreciated. Thanks in advance!

 

[gme]

I've never seen trimming to length (unless it wasn't properly chamfered) affect accuracy, sure you aren't getting walnut media in the flashholes?

 

[Dusty Stevens]

did you tumble after sizing? something went horribly wrong. trimming brass doesnt do that bad if it messes you up at all

 

[JohnKielly]

Did you chamfer the necks after trimming?

 

[jds holler]

More evidence supporting my theory that cleaning brass actually harms accuracy. jd

 

[retired]

way to many variables to resolve by guessing.
details of everything
brand of brass
bullets
powder primer
what was the load that worked in your work up
is anything new since the work up

 

[Zero333]

Thus far from what you've told us it's like others said... Chamfer/deburr case mouths and/or tumbling media in the primer flash-holes.

Probably we need more info.

 

[Dusty Stevens]

whatever theories people come up with i'll go out on a limb and say I can be confident that a different debur on your case mouth didnt make your groups from 1/2" to 2-3". now I will say that tumbling your brass after they are prepped could have caused your case mouths to be all banged up, could have gotten walnut stuck inside the case shoulder or even the flash holes, but something as simple as a primer change, bullet lot change, powder lot change- none of that will come close to what you have. we need the steps in order to load your ammo and what was different this time.

 

[br1111]

Sorry that this is a long story but I feel the whole back ground to my problem is necessary.

So last year I purchased a Remington model 700 .270 win. Being new to reloading, a friend loaded a decent load for the rifle. After shooting it for a year I decided I wasn't happy with the performance of this load so I decided to develop my own load. After shooting many different loads I had a few loads getting very close to my goal of .5" at 100 yards. By this time I had fired about all my brass 3 times and they were beginning to be too long(anywhere from 5 to 15 thou long compared to spec), so I trimmed them to 5 thou under maximum spec, give or take a thou. I also dry tumbled them in walnut chips for the first time after I had fully prepped the brass. I went to the bench and and the groups that were almost .5" before were now ugly 2-3" groups.

Was it the trimming of the cases that caused the bad accuracy or was it some thing to do with the tumbling such as residue left in the brass?

Any help is appreciated. Thanks in advance!

 

[br1111]

hopefully being new to reloading, your not putting a crimp on the bullet.

 

[fatelvis]

With the accuracy going that far off, I suspect the screws on your base and/or rings becoming loose. Check all screws for proper torque before looking at your Hand Load.

 

[370bc]

^^ This. Something lose somewhere.

 

[geraldgee]

Sorry that this is a long story but I feel the whole back ground to my problem is necessary.

So last year I purchased a Remington model 700 .270 win. Being new to reloading, a friend loaded a decent load for the rifle. After shooting it for a year I decided I wasn't happy with the performance of this load so I decided to develop my own load. After shooting many different loads I had a few loads getting very close to my goal of .5" at 100 yards. By this time I had fired about all my brass 3 times and they were beginning to be too long(anywhere from 5 to 15 thou long compared to spec), so I trimmed them to 5 thou under maximum spec, give or take a thou. I also dry tumbled them in walnut chips for the first time after I had fully prepped the brass. I went to the bench and and the groups that were almost .5" before were now ugly 2-3" groups.

Was it the trimming of the cases that caused the bad accuracy or was it some thing to do with the tumbling such as residue left in the brass?

Any help is appreciated. Thanks in advance!

The question you need to ask yourself is exactly what changed in your process to go from .5" to 2"+. The consensus is that trimming is not responsible but there is concern with the tumbling. You might be best served to review your process and rectify those things that changed including resizing your brass after tumbling. It really doesn't take much of a change to make things go sideways. Compound it with 3 or 4 changes at one time - you can easily go from 1/2MOA to 3MOA. Good luck with your reloading and be safe.

Gerald

 

[fatelvis]

The question you need to ask yourself is exactly what changed in your process to go from .5" to 2"+. The consensus is that trimming is not responsible but there is concern with the tumbling. You might be best served to review your process and rectify those things that changed including resizing your brass after tumbling. It really doesn't take much of a change to make things go sideways. Compound it with 3 or 4 changes at one time - you can easily go from 1/2MOA to 3MOA. Good luck with your reloading and be safe.

Gerald

Gerald, I respectfully disagree. That level of accuracy drop off is most likely not reloading related. I believe there is a gun/sighting system problem.

 

[MS50]

In my experience, a sudden loss of accuracy has been caused by a severely fouled barrel. Running a cheap fiberoptic scope down the barrel, viewed through my laptop, was an eye opener.

 

[Shawnba67]

Were the loads that used to be .5 from the original batch? Or recent duplicates?
Also seating depth can have a big effect.
And if your anything like me, well I get rusty if I havent shot in a bit. I cant always tell Im rusty, but my groups do!
Also go at the tube with a good copper solvent just for certainty

 

[maxscm]

A neighbor brought his 270 over to me , he said it use to shoot 1” groups, now Shoots 3-5 “ groups.
I asked him when was the last time he cleaned the bore.
He shrugged his shoulders.
I asked him does he have a cleaning Rod.
He said “ you know i’ve Been aiming to get one of those”.
He got the 270 as a Birthday Gift
When he was 16. When he brought me the Rifle he is 26 years old !!
I used sweets for the Tons of copper , then Butches to finish cleaning.
He test fired it and it shot a 1.5”
Group.
He responded , “that’s the way it use to shoot!!!
Thanks “.
I guess he’ll bring it back when he’s 36 to be cleaned again!!

 

[Bart B.]

Something changed. We don't know all the details.

I wonder how accurate someone else might shoot it..

 

[KylerB]

I'm shooting a 130 grain Nosler Accubond, CCI primers, Winchester brass, 4831SC powder( my best shooting groups in my load development process were 55.6 grains and 55.8) My reloading process was the exact same as before with the exception of the trimming and tumbling. I checked the flashholes before reloading and all seemed clear. How much deburring and chamfering is too much and too little? I made sure there was no sharp edges then I quit. The rifle was cleaned about 35 rounds ago. How often do you guys recommend i clean it? I'll check the mounts and rings when I get home tonight but I don't feel that's the problem.

 

[T-shooter]

Sorry that this is a long story but I feel the whole back ground to my problem is necessary.

So last year I purchased a Remington model 700 .270 win. Being new to reloading, a friend loaded a decent load for the rifle. After shooting it for a year I decided I wasn't happy with the performance of this load so I decided to develop my own load. After shooting many different loads I had a few loads getting very close to my goal of .5" at 100 yards. By this time I had fired about all my brass 3 times and they were beginning to be too long(anywhere from 5 to 15 thou long compared to spec), so I trimmed them to 5 thou under maximum spec, give or take a thou. I also dry tumbled them in walnut chips for the first time after I had fully prepped the brass. I went to the bench and and the groups that were almost .5" before were now ugly 2-3" groups.

Was it the trimming of the cases that caused the bad accuracy or was it some thing to do with the tumbling such as residue left in the brass?

Any help is appreciated. Thanks in advance!

Since you've already reloaded the same cases with .5" accuracy I would think you did these in the exact same way. Trimming the cases would make next to no change in the ballistics. Neither would just cleaning in a walnut chips. Is there a possibility that you had some resizing lubricant inside that made some of the walnut chips stick reducing the case volume? Any changes in your loading procedure? Same bullets? Same overall length?

I screwed up once after annealing some cases, cooling in water, then tumbled them. I though I had given them time to dry but evidently not and was in a hurry. I loaded and fired a few. Several had signs of overpressure when they shouldn't have. After checking some fired and unfired rounds, several had clumps of walnut media stuck in the inside which reduced the internal volume and created a pressure rise. Another lesson learned!