Barrel Problems

[B. Miville]

Hey folks, I have an odd issue I hope you might be able to help with.  Here is the run down:

Encore.  .257 Roberts Factory barrel.  Stratton Custom scope mount.  Weaver Zee rings.  Barrel forearm (synthetic) is "floated" using neoprene and I can easily slide a piece of paper under it so I know it is indeed floated.  Ammunition is factory Remington 117 grain Corelokt soft point.  Scope is a Bushnell elite 3200 (that was on a previous barrel before this and showed no sign of having a problem and thus is why I suspect some issue OTHER than the scope).

Ok, so here is the problem.  Last year I bought this barrel.  I mounted the Bushnell 3200 on it using a Stratton Custom mount I bought specifically for it.  I took it to the range.  I fired a 3 round group, got a VERY nice grouping...say about 3/4".  I adjusted the scope to bring the group up and over a bit.  Fired 3 more rounds for another group.  Now the grouping was where I wanted it, but started opening up again.  Fired another 3 round grouping and the placement started to drift a bit and the group opened up even more.  It was a warm day and I figured maybe it was just not letting the barrel cool enough between groups that was at issue, and even letting a long cool down pieriod did not seem to matter much.  So I put it away for another day.  That other day was today.  I dragged it out to the range to try again.  It was a chilly 32 degrees this morning, so I figured cooling between shots should be a bit easier.  I settled the gun into my Caldwell Lead Sled, lined up and fired a 3 shot group.  BINGO, 1/2"!!!!  Unfortunately it was 1/4 low on the center of the target (I had THOUGHT my last time at the range I had gotten it 1" ABOVE the bull, but whatever, it had been a while).  So I walk back to the gun and settle down for another 3 shot group.  By now the barrel had been cooling for about 6 or 7 minutes in the 32 degree air (and indeed when fring groups I still waited 2 minutes between shots) and the barrel was not even warm to the touch.  So it was a cold barrel again.  I fired.  1" above the target.  Good!  Fire second and third shots......group is now opening up.  I waited a bit, fired another 3 shot group...now things are getting erratic again.  So I walk away for a good 20minutes while I fiddle with another rifle.  Come back and fire yet another 3 shot group.  Once again the group is open and it is tough to pin point where the "zero" is.  Now, I will state that even the "wide open" groups were still within about 2 1/2 inches, so it is not like we are talking about drastic deterioration in grouping.  But what would make a rifle fresh out of the case shoot 1/2" groups and every single group from there slowly start widening?  I checked the base and it is still solid and everything it tight.  As mentioned I highly doubt it is the scope.  I don't see any burrs on the crown, and indeed if there was I don't see how it could shoot 1/2" out of the case before widening up.  I am perplexed.  Anyone have suggestions?

Brian

[halfslow]

It sounds like something is moving.
I would check the scope and mount again.  Be sure all the scope mount screws are not bottoming out.  When I put a mount on a gun, I put each screw in one at a time by itself to be sure the mount will not move with that one screw.  Only after I have tried each screw will I put all of them in.
If the mount is not securely attached to the barrel, it is possible that the heating barrel causes the mount to slip in relation to the barrel causing a small movement in the group.  The aluminum mount and steel barrel have different coefficients of expansion, and you could be seeing the result.
It is also possible that there is some built in tension on the scope mount caused by the holes in the mount not lining up with the holes in the barrel.  The temperature change of shooting will make this change the stress on the barrel causing the group to wander.

You will probably find out that the breech plate is crooked or something, but moving zero tells me the sighting device is the culprit.

[JustaShooter]

OK, I'm no expert and have been waiting on one to reply, but since they haven't I'll make a few observations:

The difference between POI on the first outing and second outing could easily be due to the difference in ambient temperature.  You say it was warm the first outing, and freezing the second.  That's probably at least a 40 degree temperature change which could easily make a 1MOA change in POI.

As to the groups opening up, I suspect one of two things, or maybe a combination of the two:  Barrel fouling and heating.

You don't say whether or not you broke in the barrel.  I know there is some controversy about breaking in a barrel, but I know for me it made a difference with the .243 Pro Hunter barrel I bought.  Cleaning got easier and easier, fouling less and less, groups more an more consistent as I broke it in.  I used the "clean every shot for 5, every 2 shots for 10, 3 shots for 15, 4 shots for 20, 5 shots for 30" method.  Then just cause I had 100 rounds, I did 10, cleaned, then 10 more and cleaned.

I know you think the barrel was cooling off between groups, but in my experience there is still plenty of heat left in a barrel 10 minutes after firing a group.  If I want to do a "cold barrel" test, I wait at least 30 minutes between groups, usually more.  Sure, being 32 degrees outside helps, but not to where the barrel is cold after 5 or 10 minutes.

Anyway, I hope this points you in the right direction.  Either that, or someone smarter than I am will hopefully post the right answer.

Just tryin' to help...

Just a Shooter

[scratcherky]

I have the same barrel and have found out that it is finicky about consistant headspace. You may want to check out the headspace with the rounds you are using. I reload so I can control the headspace.

[Lone Star]

Twenty minutes in 32F air with a .257R - the barrel is plenty cool enough.  It certainly does not need to be cooled all the way down to ambient - it has to be able to group in 90F weather when the barrel is 90F.

Fouling is certainly a possible cause.  So is the scope.  I know, it worked fine on the last rifle....so what?  Swap out to another scope and see what happens.  I'll have to trust that it is mounted correctly so that it does not move.

What about the "floated" barrel?  IME floating seldom helps much unless the forarm is warped - take out the spacers and see how it shoots.  Changing bedding pressures will open up groups too.

Shooting mechanics - are you holding the rifle the same way for the following groups?  1/2 moa is pretty good and requires some skill to achieve, unless it is luck.  List the group sizes for the day in order, that can help narrow the causes too.



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[B. Miville]

Hey guys thanks for the replies so far.

As of right now the barrel has only has about 50 rounds through it, but no cleaning was done yet.  Ill give it a swab down with Sweets 7.62 and see how that works out.  I will also swap out the scope.  Truth is I want to drop a lower power scope onto this barrel and put the 2-7x back on the .30-06 barrel when it comes back from SSK for its shortening and recrowning.  I did check the scope base and it is indeed on there rock solid.  It is a Stratton Custom base and is full steel, so there is no aluminum.  I will also take out the neoprene and see how that works out.

As for mechanics that should not be the problem. I was using a Caldwell lead sled.  The way the lead sled is made it is easy to get the rifle set into the same spot every time.  And to remove as much "human error" as possible from the equation a just barely grip the pistol grip....just enough where I can gently squeeze the trigger.  No more, no less. 

As for reloading....I do reload, but not for this round yet.  My Uncle bought me a small supply of the Remington I am using now for my birthday, and I have ben collecting the spent brass to reload once out of the Remmy factory loaded stuff.  I suppose it would be wise to also try another brand/maker.

Thanks again!

Brian

[Grumulkin]

1.  You shot a good group and then bad groups with the scope.  On another day you again shot a good group and then bad groups with the scope.  It appears the scope is capable of good groups so I don't think you have a scope problem.

2.  Different ambient temperature and humidity which result in different air density can easily change point of impact by 1 or 2 inches.

3.  The advice to make sure everything is tight is good but since the first groups out of the gun are good, I doubt a loose item is the problem.

4.  Since your grouping problem seems more related to being the first shots out of the barrel rather than barrel temperature, I doubt the problem is from barrel warping or rubbing on something from barrel heat.

5.  I doubt very much you have a barrel fouling problem.  First of all, if you start with a very clean barrel, it should take at least 30 to 50 shots before fouling is any type of an issue.

I have a 30/06 Encore barrel that had a problem the reverse of yours.  The first few groups would be big and then it would tighten up.  It turned out to be a problem with the crown.  I had inspected the crown and it looked fine to me.  I sent the barrel to T/C who redid the crown and fire lapped it and it's now one of the most accurate barrels I have starting with the first shots.

I would return the barrel to T/C and I'm sure they'll fix it for you.  All you'll be out is some time and the postage to T/C.