Cold bore flier problem - help me get rid of it

[MT_Hunter]

I am working on a hunting load and have found an accurate load (for me) with 200 gn Accubond/75.2 gn H1000/CCI250. However, the first, cold bore shot seems to shoot 2-3 inches left. The remaining 4 shots end up making a 0.8"-1" group at 200 yds.

With hunting season fast approaching I was wondering if any of you reloading gurus out there have an idea of what could be causing it or anything I can do to fix it. Since it is a hunting round cold bore accuracy is paramount. Any thoughts would be greatly appreciated.

Now for some background:
The rifle is Savage 112 VLP in 300 win mag and has the varmint contour barrel so I haven't seen any stringing due to barrel heat yet (only 150 rds down the pipe). It's been 50 rds or so since I cleaned the barrel so it is definitely fouled, but I haven't seen a drop off in accuracy so I haven't felt the need to clean it. Also, I always dry fire practice before sending the first shot so I'm pretty confident that I am not the cause of THAT big of a flier. I usually know right away if I pull it that bad.

 

[royinidaho]

Not a guru but willing to respond.

The key statement in your post is that the season is fast approaching.

Having been caught in similar situations I'd suggest the following:

1) Too late to rebed/float, etc and rezero, most probably.
2) Fire one cold bore shot for 5 or more shots at the same target. Ensure the time between shots ensures a cold bore, (hours or days between shots)
3) If the first shots maintain a good group 2-3 inches to the left then adjust the windage on the scope.
3a) Warm the barrel and ensure the second shot consistently goes in to a group 2-3 inches of the new zero.
4) If this pattern is consistent you'll know how to adjust your hold for subsequent shots after the first one.

Keep in mind that you should not need subsequent shots. That's the key to LRH. However when you do need that extra shot you'll know where to hold.

4) After the season do a thorough check out of the entire rig from one end to the other.

Consistency is a good thing even if it isn't the most desirable consistency.

 

[MT_Hunter]

Thanks for the thoughts, I'll try repetitive cold bore shots to check 1st shot consistency if I have time otherwise I'll go to my fall back load.

I agree with you that I shouldn't take a first shot if I expect to have to make a follow up shot. I will probably go to a fall back load that doesn't have a cold bore flier and still groups 1.5"-2" @ 200. It doesn't matter how good of groups I can get if the first shot is a miss.

I'd still be interested in others' thoughts as to a cause or solution to the problem. I forgot to mention the rifle is bedded and the barrel floated.

 

[royinidaho]

Thanks for the thoughts, I'll try repetitive cold bore shots to check 1st shot consistency if I have time otherwise I'll go to my fall back load.

I agree with you that I shouldn't take a first shot if I expect to have to make a follow up shot. I will probably go to a fall back load that doesn't have a cold bore flier and still groups 1.5"-2" @ 200. It doesn't matter how good of groups I can get if the first shot is a miss.

I'd still be interested in others' thoughts as to a cause or solution to the problem. I forgot to mention the rifle is bedded and the barrel floated.

Hmmmm, the fall back load doesn't have the initial flier??? Very strange, me thinks.
Unless the 200 gn Accubond/75.2 gn H1000/CCI250 load is much much hotter than the 'back up load' I would have no idea of what to look for.

If it is way hotter than the back up load, which by the way ain't bad at all for accuracy, something may be shifting with that first shot. However, once it's shifted it should stay shifted I would think.

With 50 round shot with out cleaning says that nothing that you have done between groups should have changed anything.

When you get this figured out, be sure to let us know.

 

[MT_Hunter]

The fall back load is in fact hotter than the load in question (76.4 gn H1000, NAB). Although I am getting an ES of only 14 it doesn't seem to group as well as the 75.2 gn load.

I have been shooting off of a lead sled recently and I suppose the recoil from the 1st shot could be "seating" the rifle in the rest. Perhaps this could account for it only occuring only on the first shot. I'll try some shooting just off bags and see if this makes a difference.

I'll let you know what I figure out.

 

[mkg]

I am working on a hunting load and have found an accurate load (for me) with 200 gn Accubond/75.2 gn H1000/CCI250. However, the first, cold bore shot seems to shoot 2-3 inches left. The remaining 4 shots end up making a 0.8"-1" group at 200 yds.

MT_Hunter, I have a 300wsm model 12 that had the exact same issue.
What I found was that the safety tang was just barely floating or making slight contact with the stock. The recoil from the first round would cause increased contact ( tang to stock ) the following rounds would group as you describe.
The solution was to bed the recoil lug and forward action screw , then verify that the safety tang was floating once everything was put back together and torqued down.
In my case this corrected the problem , no more cold bore fliers.

Mike

 

[Mikecr]

the first, cold bore shot seems to shoot 2-3 inches left

Not to be a smarta$$ or anything, but you could rezero the scope for that 1st shot.

 

[royinidaho]

mkg,

Great post!

One of the reasons that this is a great web site.......

 

[bigngreen]

MT_Hunter, I have a 300wsm model 12 that had the exact same issue.
What I found was that the safety tang was just barely floating or making slight contact with the stock. The recoil from the first round would cause increased contact ( tang to stock ) the following rounds would group as you describe.
The solution was to bed the recoil lug and forward action screw , then verify that the safety tang was floating once everything was put back together and torqued down.
In my case this corrected the problem , no more cold bore fliers.

Mike

Very good call!! I saw that with a 270 WSM, if I shot a ten round string it would launch a few out every once in a while. I also had it do it again when a piece of bedding chipped out and let the rear screw torque the action.

 

[kidcoltoutlaw]

I have seen it from a barrel with oil in it. Get all of the oil out of the barrel before the first shot is fired. I don't mean with a dry patch either. I have used M-Pro 7 I think alcohol would work also,

Thanks,Keith

 

[Gunpoor]

From my limited experience with rifles that have shown similar results I would suspect that the action needs to be bedded especially around the recoil lug, and I would also make sure the barrel is free-floated if you have not done so already. I can see no other logical reason for this symptom, but I have been wrong before .

 

[ANARCHIST]

Another thought is to try a different powder, just went through this with H1000 in a 300wby was nowhere as consistent as 7828 which over the years seemed to be best in most mag rifles I have owned.

Not much fun with a light hunting rifle at the bench shaking your brain loose.

7828 I never experienced problems in extremely cold weather during hunting seasons.

 

[MT_Hunter]

Thanks for all the feedback guys. It's great having the wealth of knowledge and experience this forum provides!

To the guys suggesting bedding and free floating, the action is bedded and I checked again tonight and the tang is free floated - almost excessively so. The barrel is also free floated.

Mikecr - I thought about zeroing to the first shot but in the limited shooting I have done it hasn't been consistent enough to do so. Also, I would rather go to a more consistent load that doesn't group as well rather than having to account for the 2-3 inch shift of the follow up shots (hopefully none will be needed ).

ANARCHIST - I thought a simple powder change may cure the problem, but I don't have time for this season. I imagine I'll experiment more in the off season. Also, it's peculiar how it doesn't seem to do it with other amounts of H1000.

I'll let you all know what I find when I have more time to play with the load. Thanks again for the input.

 

[SBruce]

The fall back load is in fact hotter than the load in question (76.4 gn H1000, NAB). Although I am getting an ES of only 14 it doesn't seem to group as well as the 75.2 gn load.

I have been shooting off of a lead sled recently and I suppose the recoil from the 1st shot could be "seating" the rifle in the rest. Perhaps this could account for it only occuring only on the first shot. I'll try some shooting just off bags and see if this makes a difference.

I'll let you know what I figure out.

I wouldn't be suprised if the "sled seating" is an issue to a degree. A friends new 338 Edge consistently shoots 1 moa different impact when shooting off a bipod vs the sandbags. He said it shot good groups either way, but a certain change in poi by using a different rest.

One other thought: maybe try cleaning it and shoot a few fowlers, then see if the cold bore issue still exists. Woudn't suprise me if an extreme powder fowled barrel is absorbing a little moisture or something in between range sessions. Perhaps not alot, but enough to throw that 1st shot out of the group.??

No gaurantee that either thing I mentioned is the culprit, but easy to check and not really too time consuming.