Cold Fouled Barrel POI

[One_Duck_Limit]

I've got a rifle that the POI of a cold fouled barrel is 1 MOA higher than the POI of a warm barrel. I know the easy answer is aim 1 MOA lower on the first shot, but I would really like to fix this if possible. I've checked that my barrel is free floated from the recoil lug forward and that the action bolts are torqued to 50 inch pounds (per McMillians specs). What else should I check?

 

[J E Custom]

I've got a rifle that the POI of a cold fouled barrel is 1 MOA higher than the POI of a warm barrel. I know the easy answer is aim 1 MOA lower on the first shot, but I would really like to fix this if possible. I've checked that my barrel is free floated from the recoil lug forward and that the action bolts are torqued to 50 inch pounds (per McMillians specs). What else should I check?

This is not uncommon with some barrels. Some need a fouling shot, and some don't.

I have several that need one shot first and then go to the POI for 5 to 7 shots. Other barrels don't need the fouling shot and remain on the POI until they get 5 to 10 shots down them.

On the barrels that need the fouling shot, first I thought it was the oil left in the barrel that caused it, so I dry patched them well. they were better but they still needed one shot to be dead on. so now I fire a 5 shot group to verify mu zero, clean well and fire one shot (To foul) and I am ready to go with a good first shot in the field. I will pull a dry bore snake through the bore to remove powder residue
before hunting.

On the other barrels that place the first clean barrel shot at the POI the only thing I do is dry patch
before shooting.

If a barrel has oil in it, it will change the pressure and velocity slightly causing the shot to go high and left or right depending on the twist direction. I prefer to clean all barrels good and oil them slightly for storage until I am ready to shoot them. the only difference will be that some will get one fouling shot and the others wont.

The ones that need the fouling shot, still shoot well below 1/2 MOA and some well below 1/4 MOA

In my opinion, A clean barrel is the most consistent for the first 4 or 5 shots (More than is necessary while hunting) and a fouled barrel is more consistent when shooting matches of more than 20 shots
though not as accurate. Most barrels will lose there best accuracy after shooting 4 or 5 rounds (That is the reason getting a group of more than 5 shots to maintain best accuracy is difficult and at some point around 7 to 10 rounds will settle down to consistent usable accuracy.

So if the rifle will shoot good groups after being fouled, there is probably nothing wrong with your loads or the rifle, It is just a characteristic of the barrel.

Just my opinion based on my experiences with the same problem.

J E CUSTOM

 

[One_Duck_Limit]

J E Custom,

My first shot on a cold fouled barrel is going high. Have you experienced a cold and fouled POI change compared to warm and fouled?

 

[J E Custom]

J E Custom,

My first shot on a cold fouled barrel is going high. Have you experienced a cold and fouled POI change compared to warm and fouled?

First, I consider a fouled being one that has fouled enough to effect accuracy. If you have a quality barrel, that should be somewhere between 3 and 5 shots. (There is enough copper fouling to show
with a bore scope) and at some point beyond, about all the copper that can be laid down has been.

What I call a fouling shot, is just one shot in a clean barrel to remove any oil and possibly season the bore just a little. after the first shot the barrel conditions remains fairly consistent for a few shots and is not effected by copper fouling. Once a barrel fouls or heats up, things change and not always for the better.

One shot will/should not heat up a barrel enough to change the POI unless the bedding or something else is wrong. But after a few shots (Especially the big magnums) heat can become an issue.

I would recommend that you clean your barrel back to the white, start shooting a single group
with 5 minute pauses between shots keeping track of each shot and see what your barrel does.
this should tell you what your barrels likes and at what point you need to stop and clean. All barrels are slightly different and sometimes need different care.

J E CUSTOM

 

[waltercrouse]

First, I consider a fouled being one that has fouled enough to effect accuracy. If you have a quality barrel, that should be somewhere between 3 and 5 shots. (There is enough copper fouling to show
with a bore scope) and at some point beyond, about all the copper that can be laid down has been.

What I call a fouling shot, is just one shot in a clean barrel to remove any oil and possibly season the bore just a little. after the first shot the barrel conditions remains fairly consistent for a few shots and is not effected by copper fouling. Once a barrel fouls or heats up, things change and not always for the better.

One shot will/should not heat up a barrel enough to change the POI unless the bedding or something else is wrong. But after a few shots (Especially the big magnums) heat can become an issue.

I would recommend that you clean your barrel back to the white, start shooting a single group
with 5 minute pauses between shots keeping track of each shot and see what your barrel does.
this should tell you what your barrels likes and at what point you need to stop and clean. All barrels are slightly different and sometimes need different care.

J E CUSTOM

 

[waltercrouse]

I have light contour barrel win. mdl 70 post 64 action in 7 rem. mag. With a cold barrel it shoots dead on but as it warms up the group will rise above the target. The barrel is 3/4 bedded and only has short amount of free floating in the stock.

 

[One_Duck_Limit]

I ran JE Customs test last night. The gun shot a nice .75" 3 shot group at 200 yards. The POI stayed consistent. This may have been operator error when I noticed a POI change. I'm going to test it again tomorrow.

 

[ultraedge]

I think this issue is caused by residual stress in the barrel. I have a premium cut rifled barrel in .338 EDGE that does the same thing. The best chance of fixing the problem is to have the barrel cryo treated. There is about a 50% chance of success. The only time my barrel doesn't shoot 1 moa high on the first shot is when it has been sitting in the truck cab on a hot day and is already hot to the touch. Gary