Assuming all being equal, dirty bore consistent, how much is your cold bore shot off of normal follow up shots?

What us your experience? I am shooting 168 FGMM ammo.

Thanks,

77

Less than one minute.  Always high and left

About 0.3 mil (which is about 1moa) for a cold bore.  Shot goes a bit left.

On a dirty bore I haven't noticed much of an issue with cold bore shots.  I only have 2 precision rifles so it's not a large test size.  When I have had a flyer on the cold bore shot it has been my fault.   Clean cold bore is a different story usually takes a couple rounds before it starts to group.

Thanks,

Mine was about 1.5 minute, low, possibly my fault, the next three shots were 5/8"

Anyway, my next trip to the range will be this weekend, will start with my standard ammo and see what happens.

Thanks,

77

How many take dry fire shots before making a "cold bore" shot? Makes a big difference that I have seen.

I try to do this on all my range trips, it especially helps when shooting pistols in my experience.  I've also found it to be beneficial to take a break every so often to dry fire between shots, if you aren't used to heavy recoil it really helps eliminate flinching.  Very good habit to have.

Good idea and thought...will try that this weekend

77

depends... with my AIAE, i have no shift

good post on it...



and the CB challenge...

Can't view the target on the old snipershide forum to print it. :(

It maters not what My Guns doe with a CB shot or even a CCB shot.
What maters is what YOUR guns do in those conditions.
There is an easy way to find out::
a) every time you go to the range take an extra target
b) shoot your first, second, and third shots at this target
c) Then use a different target for the rest of the fun.

After a couple of dozen trips, you will have enough data to tell you
a) if the CCB shot is consistent and what the accuracy is
b) if the CB shot is consistent and what its accuracy is
Only after you know this will you be in a position to use the knowledge.

O

This is what I basically do, put three targets out and go from there.  I have some Blackhills ammo to try this weekend.

CCB shot?  Not familiar with this acronym?

77

CCB= clean cold bore

Thanks....the company I work for invented the use of acronyms. I should have figured it out

After I shoot different ammo this weekend I will find out if I have a CB issue.

Thanks.

77

If it's like mine it'll vary with the load.  My Savage has a predilection toward high and left regardless but the amount of the shift varies with a given load.

I havent seen a CB shift on any of my guns.

My CB shot was about 1.25" low and left.  Then after another 5 rounds, I peeled off this group, 4 rounds Honnady Match, 168 grain

I still have a lot to go, as you said the barrel need to settle in.  

77

Did you do any dry fire practice shots before your cold bore shot?

Whats a barrel settling in? Are you talking about coppering up the barrel?

Always. Its interesting to see people grab a cold rifle after they've already been shooting other guns. Most of the time the CB shot wont be off. Its almost like the shooter is cold not the rifle.

Yes, that is what I am referring to.  As noted I am real new to this precision rifle scene.  After doing a lot of reading and listening to the experts on this forum, it seems a groove sweet spot needs to be developed. A balance of fouling vs. accuracy.  I tried different ammo brands today and each one does have its own grouping cluster around the POI.  

77

Yes I did about 10, against an AZoom dummy round.  Seems to work.  Rifle on a bipod, rear supported by me, no wedge or monopod.

77

 
When shooting I can usually call my "shots" as to where they will go. Even more so when dry fire shooting as one doesn't have the recoil and sound distracting you. When you shot low and left on your CB, did you notice anything like this?


I'm a firm believer that a CB shift, more times than not, is due to a "cold shooter".

 
Exactly.

I shoot mine tell I see accuracy starting to open up. Normally it takes thousands and thousands of rounds then about 20 fouling shots after cleaning.

I don't clean my bore anymore. It changes too much about how the gun shoots for too long to be a benefit.

What maintenance do you do?

Clean the chamber. Clean the bolt. Lube everything. That's about it.

I'll shoot them till they quit and then maybe clean the bore, but it's usually time for a new barrel.
It takes around 100 rounds for them to settle down again after a good cleaning.

Although it's a semi-auto, my Mk12 is consistently about 1MOA low from the center of the ensuing group.

LE Snipers live by this, or hostages may die by it!

Having seen hundreds of targets through instructing both LE & MIL snipers, I have seen everything from shifts as drastic as 1.5 MOA to no detectable shift at all.

Why is that the case?

Shooter - per above, many times it is not a cold bore issue, it is a cold shooter issue. We stress to all of our students to take as many dry fire shots as they can before going hot, but we also intentionally put them in situations where they will not be given that luxury. That is where we can readily identify, based on their previous qualification targets, if any shift was due to the rifle or due to the shooter.

Stress in the System - it can be in the barrel, in the receiver stock interface, or in some other part of the system, but many rifles will have stress(es) in the system that will take anywhere from one to multiple shoots to settle in and shoot consistently. Needless to say if we identify a student with one of these rifles, we do our best to fix it if possible (check torque on action screws). If not fixable (bad stress in a barrel), we have pulled students from the class and told them that they need to come back with a better system.

Clean Bore - also per above, you need to be aware how the rifle will perform based on the status of the bore. We spend a lot of time with our students making sure that they understand the cleaning process and how to best manage cleanliness, serviceability and optimal performance. It is very common to have students who don't listen and fail their early morning quals because they over clean their rifles at night, and come back with a clean bore that is not shooting as they expect.

There are some other variables that can come into play, though they will be more of an overall issue. For example your environmental variables, so taking a Cold Bore shot when it is 20F versus taking one when it is 90F. Using a suppressed rifle is another big one.

As someone pointed out above, if you are a shooter that must have a known cold bore shot, then you need to:
- document every cold bore shot that you take, and note any patterns (are they consistent or predictable?)
- understand everything that is going into your cold bore shot, and be able to manage those variables as needed

I know of some shooters how have this nailed down 100%, and others who don't have any clue at all.

Best of Luck,
M Richardson

for the newbs

the above is not good advice, shoot till your accuracy falls off, it will.

I

I know this is general knowledge to everyone, but unlike my 5.56 semi autos, I caanot just load any ammo and have fun, my data will be built around one load, one ammo, one set of specs.

The only way I can really get what I want, reloading is the next step.

Thanks

77

I use 3"x5" note cards, with a measured 1" square. Take my first CB shot at it. Keep em, with a mark of up/down left/right orientation.

Mostly though, any variance I've experienced is me.

And, I don't clean the bore, unless the rifle got submerged, or if accuracy just went to hell. I just lube/clean bolt, trigger mechanism, raceway.

Very good advice, I do like the index card approach. I have been taking the targets and cutting them out, into a log book.  I am also learning about your advice on the cleaning.

77

Taking the copper out is pointless and it doesn't hurt anything. If you strip the copper out every time you shoot your doing far more damage then not cleaning it. I bet you would be hard pressed to find anyone in PRS thats cleaning the copper out of his barrel after every time he shoots. Everyone of the guns I've owned and everyone I talk to agrees that after you clean your gun your groups will tighten up after you foul the barrel and get the rifling copperd.

fwiw, (as a PRS shooter) i think copper free barrels shoot best.  however i am in the minority in thinking that by doing an extremely minimal breakin, my barrels don't get copper fouled in the first place.   The carbon fouling doesn't bother me.

I don't have a cold bore shift.  I do have a clean bore shift, and it takes about 5 rounds to settle in, according to both the magnetospeed and the holes in paper.  but I go several hundred rounds between cleaning, and i'll always leave my barrel fouled after cleaning so i essentially have no shift to worry about.    the next round will go where i expect, whether it's the first round of the day or the last round in a 10 shot string.


for reconb4, consistency is the key.  we just have different views of what is most consistent.    

As you start from a pristine clean barrel and shoot thousands of rounds, carbon fouling starts at zero and builds up, but it does not continue to build up infinitely or to where it has clogged the bore.  It reaches its own state of equilibrium which is remarkably consistent.   Velocities with SDs in the low single digits are achievable, as well as tiny groups on paper.   I don't believe it wears the barrel any faster.    So the mentality is simply that this is more consistent than the alternative, which is as you described, frequent cleaning and tracking shifts for clean vs fouled shots