Please tell me what's wrong with my rifle

[old_dood]

it's a 12BR. I did a ladder test with Berger 105 hybrids. Powder is N150 CCI BR4 primers, about .010" jump. I started exactly with what Berger states in their manual, 27.5g with a .3g increment up to 30.2g which is less the the max load in the book. here's the problem. well into the test, but before getting anywhere near my max load, I'll start getting very heavy bolt lift for a few shots and then it will stop. I'll progress up to heavier loads and it will happen again for one or two shots and then stop again. I managed to get up to the max load and bolt lift/extraction was fine but I suspect, had I kept shooting , eventually it would happen again.

My loading equipment is Forster Coax, Redding Type S dies, Cambridge FX201 scale. The rifle has been bedded, SSS ejector, bolt lift kit from Stockade. Barrel is a Criterion from Northland. PTG go and nogo gauges used.

this sort of thing happens with other, known good loads also.

Al

[limige]

Are you absolutely sure on lengths? Did you measure every round to the ogive?

Sounds to me like you were seated 0-.003 off the lands and getting pressure spikes from slight variations in length. Do you use a OAL gauge and a quality set of calipers using a comparitor to measure off the ogive?

So dies dont repeat as well as others. Also bergers require special seating stems which often are sold seperate. You may be getting a ring on the bullet where the seater presses against the bullet. Others may see smashed tips.

I would either back the die off another .005 or run them jammed for ladder testing.
jammed will show max pressure at the lowest possible charge weight. Personally I haven't done that.

[Jetpig]

1. Is the brass all the same make? different brass, different case capacity, different pressures.
2. Is the brass all trimmed to the same length and UNDER max length?
3. Is your brass all sized the same? Neck or full length, not mixed?
4. Same primers? I assume so.
If all these are a yes, I would go with Limige and say you have some variation from olgive to lands length. Also, how did you determine your OAL to the lands? Did you use a precision gauge or did you determine length like us Western boys do?

[Jamie]

Are you absolutely sure on lengths? Did you measure every round to the ogive?

Sounds to me like you were seated 0-.003 off the lands and getting pressure spikes from slight variations in length. Do you use a OAL gauge and a quality set of calipers using a comparitor to measure off the ogive?

So dies dont repeat as well as others. Also bergers require special seating stems which often are sold seperate. You may be getting a ring on the bullet where the seater presses against the bullet. Others may see smashed tips.

I would either back the die off another .005 or run them jammed for ladder testing.
jammed will show max pressure at the lowest possible charge weight. Personally I haven't done that.

+1. Sounds like you are right at the lands with inconsistent lengths. I would back off a little more, or in the case of my rifle about .040 off the lands.

[wbm]

Good luck.

[chukarmandoo]

I think it is also OAL that is messed up. For a ladder test I would make sure the bullet is in the lands for the test and start at the lower powder charge and work up. If you start in the lands now you'll know later when you adjust OAL that you won't be over pressure. Remember right now you're just trying to find nodes. Later you'll shoot for accuracy.

[old_dood]

1. Is the brass all the same make? different brass, different case capacity, different pressures.
2. Is the brass all trimmed to the same length and UNDER max length?
3. Is your brass all sized the same? Neck or full length, not mixed?
4. Same primers? I assume so.
If all these are a yes, I would go with Limige and say you have some variation from olgive to lands length. Also, how did you determine your OAL to the lands? Did you use a precision gauge or did you determine length like us Western boys do?

Brass is all from the same box and all lengths are within .002" of each other. I use a Mitutoyo caliper and the Hornady tool for measurement to the lands. I usually measure the length to lands at least 3X then measure right on the tool. when I seat, I reduce that number by .010" and measure about every 10. All cases are FL sized. I have the VLD stem in my seater.

One thing that concerns me is the way bullets feel when I measure OAL. I installed this new barrel around January but didn't start shooting until early April. On my old factory barrel, when I'd press a bullet into the lands, it would got to a certain point and then stop. On the new Criterion, the bullet will go to a certain point with minimal force and stop, but then, if I push a little more, it will go further. This is when using the Hornady OAL tool. the difference between first feeling resistance and the point where the bullet absolutely stops, is over .100. Since I'd never installed a 3rd party barrel before I wasn't sure if I should be concerned about these findings. Now I'm beginning to wonder if the chamber on my barrel was not cut correctly. I'll be calling Criterion on Monday.

[jonbearman]

Sounds like a carbon ring in the neck area of the chamber.Get it borescoped to see if that is the problem and then the task of cleaning it out with jb bore paste or iosso bore paste.I use the next size up brush(nylon) and turn it by hand to get rid of the ring of carbon that forms in the neck throat junction.The ring will cause over pressure erradically while shooting as the ogive is in a different spot as they vary in length if not sorted into groups.

[old_dood]

Sounds like a carbon ring in the neck area of the chamber.Get it borescoped to see if that is the problem and then the task of cleaning it out with jb bore paste or iosso bore paste.I use the next size up brush(nylon) and turn it by hand to get rid of the ring of carbon that forms in the neck throat junction.The ring will cause over pressure erradically while shooting as the ogive is in a different spot as they vary in length if not sorted into groups.

the anomaly I mentioned was there before I fired a single round through the barrel. I noticed it the first time I used the Hornady tool to set up my first loads.

[sharpshooter]

Try a different powder. I don't know of anybody using N150 with any luck. Try Varget, Rel 15, H4895 or 8208.

[emtrescue6]

Try a different powder. I don't know of anybody using N150 with any luck. Try Varget, Rel 15, H4895 or 8208.

+1 Or WIN 748 or IMR4064....

[old_dood]

Try a different powder. I don't know of anybody using N150 with any luck. Try Varget, Rel 15, H4895 or 8208.

+1 Or WIN 748 or IMR4064....

as I said in original post, it happens with other loads, specifically 31.0g IMR 4895 under 80g FB.

[1.618]

I would remove the Stockade bolt lift kit just to see if that may be a factor in the periodic bolt lift problem.

+100 at least until the heavy bolt lift issue is sorted out.

[Rooster 50]

Sounds like a carbon ring in the neck area of the chamber.Get it borescoped to see if that is the problem and then the task of cleaning it out with jb bore paste or iosso bore paste.I use the next size up brush(nylon) and turn it by hand to get rid of the ring of carbon that forms in the neck throat junction.The ring will cause over pressure erradically while shooting as the ogive is in a different spot as they vary in length if not sorted into groups.

+1 on the carbon ring. This can cause pressure spikes quicker than you would think possible. BTW have you by chance tried looking in the throat and chamber with a borescope. This might answer a lot of questions for you.

Another thought is that with the hybrid ogive you do not need to be so close to a jam why not back off 50thousandths and work your way back in. You might be surprised by where it will shoot well.

[old_dood]

One thing that concerns me is the way bullets feel when I measure OAL. I installed this new barrel around January but didn't start shooting until early April. On my old factory barrel, when I'd press a bullet into the lands, it would got to a certain point and then stop. On the new Criterion, the bullet will go to a certain point with minimal force and stop, but then, if I push a little more, it will go further. This is when using the Hornady OAL tool. the difference between first feeling resistance and the point where the bullet absolutely stops, is over .100. Since I'd never installed a 3rd party barrel before I wasn't sure if I should be concerned about these findings. Now I'm beginning to wonder if the chamber on my barrel was not cut correctly. I'll be calling Criterion on Monday.

does anyone else have an opinion that there could be something wrong with the chamber? again, I noticed this before I ever shot through this barrel.

[emtrescue6]

does anyone else have an opinion that there could be something wrong with the chamber? again, I noticed this before I ever shot through this barrel.

Anything is possible...but it's way down the list of other more likely options that I would work on first in my opinion...

[sharpshooter]

Just thinking out loud here....when's the last time you greased your bolt lugs and cocking ramp? I don't think it's in the load, I think the problem is in the bolt itself. Check your cocking sleeve to see if it has any shiny rub marks on it.

[keeki]

Have you tried to rechamber the spent brass that was heavy on the bolt to see if it would lift heavy consistently? I'm thinking bolt issue, not load