Hot barrel shoots better than a cold one?

Discussion in 'Big Stuff--7mm, 30 Cal, .338+' started by spudgun, May 27, 2019.

  1. spudgun

    spudgun

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    Have been trying to dial in my T/C Compass, 308 win for some time.

    I hope I will answer all concerns first about this gun.
    1. full free floating barrel (hot and cold)
    2. Vortex PST II, 6-25X50
    3. Scope rings have been lapped
    4. 22" barrel
    5. 1:12 twist rate.
    6. shooting 168g HPBT hornady, 43.0 g Varget, 2625 FPS avg.

    My last visit to the range supprised me with the results I got. This gun had been shooting 4 MOA at 100 yds for some time. changed out scope, got the trigger down to 2.5lb pull, tried different bullet weights and powders.

    The target below is my shooting results at 100 yds with the above load. What i found strange is the accuracy and barrel temps.
    1. First group was at the 5 O'clock target. barrel temps about 65 deg.
    2. Second group at 11 O'clock, barrel temps about 80 deg.
    3. Third group at 7 O'clock barrel temps was 143 deg.
    4. Forth group was dead center and barrel temps over 160 degrees.

    I was always under the impression that the hotter the barrel the groups got worse.
     

    Attached Files:

  2. hogpatrol

    hogpatrol Don't criticize the farmer with your mouth full. Gold $$ Contributor

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    What's your cleaning regimen? Are you scrubbing it squeaky clean between range visits?

    Aside that, have you tried RL15?
     
  3. ballisticxlr

    ballisticxlr

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    Is it repeatable or is this a one-off where you got a mysterious good group from ammo the gun otherwise doesn't seem to like?

    Also, you shouldn't shoot the gun that hot. Should stop when it gets hot to the touch.
     
  4. Ringostar

    Ringostar

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    Maybe it did get worse. Is that a flier in the one o’clock target?
     
  5. spudgun

    spudgun

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    No on the flyer. I had 1 round of a older load that I wanted to shoot off.

    Cant tell at this time. I ran out of 168 bullets to reload. I did get some last night and will reload and run this test again.

    I know about barrel temps and normally stop shooting when my temps get about 140 degrees. This time I only had 3 rounds left and so I shot them at the center target.


    No I am not cleaning it squeeky clean. Learned my lesson with my 6.5 CM. after removing copper fouling my 600 yd groups went to hell. Took 16 rounds to get the grouping back to 3/4 MOA. Haven't cleaned it again....LOL
     
  6. Milo 2.0

    Milo 2.0

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    You say 4 moa, so 4" ?
    How did you come about this load?

    Now I have never shot a 308, but I have scanned load data, is it possible that once the barrel got hot, your ammo got warmer while baking in the chamber waiting for you to pull the trigger, resulting in a warmer load? And subsequently better groups. Reason I ask is I seem to recall most run a little warmer charge.

    How many 4" groups do you need to view before you move on to something more productive?
     
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  7. hogpatrol

    hogpatrol Don't criticize the farmer with your mouth full. Gold $$ Contributor

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    spud, need more info. What have you tried in the way of primers, powder, brass, bullet seating depth, how much time between shots? Is the stock factory or aftermarket? Action bedded? At present this is all just a guessing game.
     
  8. 243winxb

    243winxb

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    Hot or cold, gun would be sold, if mine.
     
  9. Milo 2.0

    Milo 2.0

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    Lol, a barrel that shoots 4" needs to be cut in half, not resold.
     
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  10. hogpatrol

    hogpatrol Don't criticize the farmer with your mouth full. Gold $$ Contributor

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    Or recrowned. Issues like this are hard to diagnose over the internet.
     
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  11. theallcineyes

    theallcineyes

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    One thing that was not mentioned here is dry firing. When I get to the range and get set up, I dry fire my rifle 3 or 4 times while I carefully focus on my scope reticle watching for the slightest movement. Usually after one to 2 dry firings I find myself settling down to where I can pull the trigger without any movement showing up in my scope. This, along with MINIMAL rifle bore maintenance, and good ammo, will produce sub MOA cold bore groups from my 700P almost every time.
     
  12. spudgun

    spudgun

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    Well, let me say that I have tried factory loads, reloads with 150, 168, 180 gr bullets both factory and my reloads. Powders have been H335, varget and H4895. cases are all federal (cases weigh 181.0-181.5), primers have always been CCI.

    For a new gun I was dissipointed with the first factory and hand loads. when I say 4 MOA i am not kidding. At one point I strongly thought the scope was bad, changed to another Vortex and had same issues.

    I did finally started testing OAL. Found that 2.83 OAL ( .04" jump) was giving me the best groups.

    Timing between shots would be less than a 90 seconds between each 5 shots.

    Velocity between first shot and last shot avg 2625 FPS.

    Factory plastic stock no real bedding to speak of. If I decide to keep this gun, it will be restocked with a better stock.

    I did inspect the crown, I have seen worst ones on other guns, powder marks are even all around the crown.

    Thunderstorms today so no shooting for me. Will be reloading the same as before and see if I can duplicate these gruops again.
     
  13. 6MMsteve

    6MMsteve Gold $$ Contributor

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    try the Horny 178 BTHP
     
  14. spudgun

    spudgun

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    well, everyone loves a good mystery. i think I can work around the 43.0g load to see if I can get it tighter.

    Noticed a break in the rain so I loaded up and went to the 100 yd.

    I did find one thing out this gun or barrel does not like 44g of Varget behind a 168 HPBT.

    I did load the same cocktail as before (43.0g Varget, 181g cases, 168g HPBT).
    Also loaded up some 44.0 g, Varget, 181g cases. OAL 2.83, .03 leade jump.

    My first group, 5 O'clock, (43.0g Varget) except for the one I pulled was 1 MOA. Cold barrel 65 deg. 2530 AVG FPS.
    My second group, 7 O'clock, (44g, Varget) was 2.5 MOA. barrel temp 135 deg, 2754 AVG FPS.

    Let barrel cool down to 80 deg.

    Third group was 2 O'clock, (44.0 Varget), 2.5 MOA, barrel temp 120 deg,

    Fourth group was center, (43.0 Varget), 1.5 MOA, barrel temp 140. 1, pulled shot.

    Not what happened before on the barrel temps and groups.

    I think I will be experimenting around the 43.0 g mark.
     

    Attached Files:

  15. timeout

    timeout Silver $$ Contributor

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    I see that you are from Madison. I'm about 45 miles South of there. I have been down the road you are on with factory barrels and my advice is not to waste any more time or components on that rifle. If you really love the rifle and want to keep it, have a quality barrel installed. Otherwise if you just thoroughly enjoy a challenge, keep up the good work!!
     
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  16. spudgun

    spudgun

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    Thanks for the encourgement. Can't complain too much. I won this gun at our club raffle.
    So i really got nothing into it. All the high cost stuff I already had laying around. I know it's only a $200.00 gun, but what the heck.

    I kinda went through this with my Savage 12 F/V, 6.5 cm. Took me not as long but was some expermination with loads and bullets and a good stock to get it to shoot 3/4 MOA at 600 yds.

    Besides I'm retired and love to shoot.

    If I can't make it a 600 yd shooter then I'm going to sell it to my brother in law. With the groups it is shooing at 100 yds it should kill a deer...;-)
     
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  17. Fred B.

    Fred B. Gold $$ Contributor

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    T/C compass bolt face is by a pin to bolt body. Make sure it is in place properly. Next, get a limbsaver or similar rubber tuner and start testing with tuner. My compass 6.5 CM shot under 1/2 moa with Hornady ELD-
    M ammo.
     
  18. D-4297

    D-4297 Silver $$ Contributor

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    My thought would be to save a lot of time and money and get the action out of the plastic stock , and get it into a quality stock that can be pillar bedded , and full bedding job . Full free-float barrel , and you might find out you have a nice little 2-300 yard hunting rifle . Went through this with a friend who bought a moderate priced ( cheap ) hunting rifle . Did the stock change-over , and it shoots 1/2 MOA at 100 yards now . The original stock was ALL of the problem . And the only problem . And BTW , his "Before" targets looked exactly like yours do now .
     
  19. boltfluter

    boltfluter Gold $$ Contributor

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    Bed the rifle or replace with pillar bedded stock. You are just wasting time and money if this is not addressed. Been down this road several times. Tha 3 b's, bedding, barrels, and bullets. :D:D

    Paul
     
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  20. Fred B.

    Fred B. Gold $$ Contributor

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    Actually, bedding is not a bad idea.
    Bed the entire rifle in fast setting concrete.:D
     
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