222 Rem Lost Accuracy at 500 Rounds?

[toasty]

So I have a custom 222 Rem for the first 500 rounds was shooting lights out with a Nosler 40gr BT. I would regularly get .200" groups at 100 yards with very little effort if the wind wasn't too horrible. I would need to extend the seated bullet by about .010" about every 200 rounds. I even had a factory hornady 50gr load that shot .200". I loaded up a couple dozen rounds to check seating depth again and I am getting .75" groups with mostly horizontal regardless of seating depth. The factory load is now also at .75" No changes to anything gun or ammo related, checked action screws, scope etc.., and velocities still good with single digit Std dev. What do you guys think is going on? Going to do a good carbon scrub with JB bore paste. Any other suggestions?

 

[rwj]

If you have (or access to) a bore scope, inspect the barrel throat and crown.

 

[Gary in MD]

500 rounds isn’t much on a Triple Deuce.
How do you know that the scope is good?
Exactly same lot of components?

 

[Rook 6]

Not going to pretend I know exactly what’s happening but if I’m understanding correctly, you are getting the opened up groups with both hand loads and factory. All previous suggestions are good. Just brainstorming, was your bench technique any different? Rest setup different? Muzzle crown un-disturbed? Wouldn’t hurt to strip, clean and lightly re-oil your bolt either. Lots of other variables I’m missing no doubt.

 

[clowdis]

.010 seems excessive after only 200 rounds. You don't say total number of rounds but I assume around 600+. That means you have extended your seating depth .030 or more which might be enough to jam excessively. Have you tried an OAL where you started from?

 

[Infrequent Shooter]

So I have a custom 222 Rem for the first 500 rounds was shooting lights out with a Nosler 40gr BT. I would regularly get .200" groups at 100 yards with very little effort if the wind wasn't too horrible. I would need to extend the seated bullet by about .010" about every 200 rounds. I even had a factory hornady 50gr load that shot .200". I loaded up a couple dozen rounds to check seating depth again and I am getting .75" groups with mostly horizontal regardless of seating depth. The factory load is now also at .75" No changes to anything gun or ammo related, checked action screws, scope etc.., and velocities still good with single digit Std dev. What do you guys think is going on? Going to do a good carbon scrub with JB bore paste. Any other suggestions?

possible rapid fire over a looong day of shooting?

 

[snert]

I have a 222 with over 2000 rounds thru it and I am at about .o40 longer than when it started. Is your barrel made of soap? I know that sounds silly, and no disrespect, but that is a lot of erosion from a Duece. I'd really take a look in there and I would consider that maybe you are getting false readings on the measurements.

 

[toasty]

Thanks for the ideas. Checked my journal and the last accurate rounds I shot I was seating out .015" from the original accuracy node at 500 rounds, so not quite as much as I posted above. Just checked my scope with a Leupold Zero Point and did the 2moa box with the turrets. Dead on, if it was the scope, that test usually shows it. This is a pdog gun and it has been out in the field, but never shot to where barrel was hot to the touch. It has been 50-100 rounds between cleanings on those days. Same lot of components.

 

[Schippergreg]

Are you using any sort of wind flags? It doesn’t take much to push a 40gr bullet

 

[AlNyhus]

First, I'd suggest you go back and verify where you're at to the rifling using the stripped bolt (Wheeler) method.

 

[K22]

I had over 5,000 rounds through my sporter weight Rem 700, 222 before there was any significant increase in dispersion attributable to the rifle and all I ever cleaned it with was Hoppe's 9 and a bronze brush about every 50 rounds or so. Therefore, I would be surprised if it was something to do with the barrel or cleaning although everyone these days seem to attribute accuracy problems to cleaning issues.

My load was with IMR 4198 and Sierra 50 grain bullets in a 14' twist. Given all that you say you already checked, if dispersion is opening up in the horizontal, the first issue I would suspect is wind, especially at the precision level you are shooting / expecting, i.e. 0.200. The next culprit I would suspect is heavy mirage boil up and to the right or left.

The next suspect would be the shooter, no insult intended. When things start to go sideways for me in my highly precision rifles, I can usually trace it back to me. It doesn't take much failure of cheek weld, shoulder pressure, trigger control, and / or follow though to open up a 0.200 group.

 

[NH30]

Quoting K22, above, "It doesn't take much failure of cheek weld, shoulder pressure, trigger control, and / or follow though to open up a 0.200 group."

That is true.

 

[ronemus]

Your cleaning regimen comes into play as well - if you've accumulated sufficient copper or hard carbon in the bore accuracy will degrade. Now that the inexpensive Teslong borescope is available, everybody should have one. It's easy to develop a good cleaning procedure when you can see the state of the bore. I find the following works for me:

1 wet patch with Hoppe's #9, allow to soak
10 passes (back and forth = 1 pass) with a bronze brush wet with Hoppe's
dry patch
10 passes each with 2 patches of JB bore paste
dry patch
if copper remains, 1 wet patch of KG-12 allowed to soak
dry patch
I moly coat bullets, so 10 passes with a patch of Midway Moly Bore Prep
for chromoly barrels, 1 patch with CLP
dry patch

Always use a bore guide - the throat can be damaged quickly without. Always use a 1-piece rod; there is debate about coated vs. bare rods, but I favor coated BoreTech rods.

 

[nakneker]

500 rounds is premature for a 222 to loose any measurable amount of accuracy. I’ve owned 222s all my life many of which have high round counts. The throat shouldn’t be getting eroded that fast unless you’re shooting it while piping hot and you already answered that question. It points to barrel fouling, loose rings or mounts, you’ve checked the scope so that’s not it. Hopefully a good clean restores the .2 accuracy, impressive by the way. Update us on how it goes if you would.

I have one factory 222 that shoots in the .2s, sometimes better, it’s a Tikka Master Sporter. I have two custom hunting 222 hunting that shoot about that good too, it’s lot of fun when a rifle shoots that good.. Best of luck to you.

 

[toasty]

So here is an update for those that took the time to respond. Ultimately the root of the issue was that I was shooting with temps in the 90s the last few weeks when I did all of my load development in the 50-60s. The mirage from the barrel on a hot day also affects my groups. In my last session, I was reading about 30-40fps faster speeds than in my notes. I ended up increasing the neck tension on these loads and dropping the powder charge by .1 grain. These 2 things reduced the speed to match what was in my notes and groups down to .3-.4 inches. I just shot a seating depth test this morning with a little cooler air and at a seating depth of .003" further out than the last time I did a seating test and shot a .18" group with all other groups in the .3s. Not sure if that group was just random distribution, but either way, I am back to the accuracy that this rifle expects. Thanks for all of the tips and good info, I learn something new just about every day I load and shoot.

 

[ssv1761982]

So here is an update for those that took the time to respond. Ultimately the root of the issue was that I was shooting with temps in the 90s the last few weeks when I did all of my load development in the 50-60s. The mirage from the barrel on a hot day also affects my groups. In my last session, I was reading about 30-40fps faster speeds than in my notes. I ended up increasing the neck tension on these loads and dropping the powder charge by .1 grain. These 2 things reduced the speed to match what was in my notes and groups down to .3-.4 inches. I just shot a seating depth test this morning with a little cooler air and at a seating depth of .003" further out than the last time I did a seating test and shot a .18" group with all other groups in the .3s. Not sure if that group was just random distribution, but either way, I am back to the accuracy that this rifle expects. Thanks for all of the tips and good info, I learn something new just about every day I load and shoot.

Thanks for the update. So many times we are left hanging...

 

[L1986]

So here is an update for those that took the time to respond. Ultimately the root of the issue was that I was shooting with temps in the 90s the last few weeks when I did all of my load development in the 50-60s. The mirage from the barrel on a hot day also affects my groups. In my last session, I was reading about 30-40fps faster speeds than in my notes. I ended up increasing the neck tension on these loads and dropping the powder charge by .1 grain. These 2 things reduced the speed to match what was in my notes and groups down to .3-.4 inches. I just shot a seating depth test this morning with a little cooler air and at a seating depth of .003" further out than the last time I did a seating test and shot a .18" group with all other groups in the .3s. Not sure if that group was just random distribution, but either way, I am back to the accuracy that this rifle expects. Thanks for all of the tips and good info, I learn something new just about every day I load and shoot.

What powder are you using?

 

[toasty]

What powder are you using?

IMR 4198

 

[durand mortenson]

IMR 4198

IMR and H4198 were my favorite powders for 60+ years. I went to Hodgdon eventually assuming the shorter grain would throw better and be more accurate. I never did a test on paper as I was just shooting ground squirrels on a ranch and couldn't tell the difference.

The rifle is a Rem 722 222 and was a tack driver, but after several thousand rounds and over heating a time or two it is still fun to shoot..... Mike Walker had his act together

Mort

 

[Savagenut71]

If you have (or access to) a bore scope, inspect the barrel throat and crown.

I have one and it looks very very nice