Carbon Fiber Barrel Accuracy

[brentc]

case preps a little sloppy as I don't sort brass. i have other rifles that i can shoot bughole groups repeatable at 200 yards with same brass prep. in this case, im talking sand bags and rear bag, this particular barrel will shoot 1.25 inch at 220 yards and no better. but.... it did before about 200 rounds. ive never experienced this before. im ok with it but thought it was worth discussing. this is what it used to do...View attachment 119712
this is what it did today.View attachment 119713

Have you tried different primers?

 

[brentc]

Are they free floating or full length bedded?

The MPRs are fully floated chassis rifles.

 

[tvarden]

I ordered an MPR last week in 338 Lapua

 

[Truk505]

The MPRs are fully floated chassis rifles.

Is it free and clear? Isn't there a band about a third of the way down where it's attached as well?

 

[mountaincarver]

Have you tried different primers?

no, but maybe.... ill try and see. cant hurt. ive been using cci but ill throw in some federal 210s.

 

[mountaincarver]

Is it free and clear? Isn't there a band about a third of the way down where it's attached as well?

the mprs stock stops where the barrel threads to the action. from there, a small 1 inch or so protrusion sticks out with several threaded holes to accept a forearm made of carbon fiber to bolt on. fully floated. pretty cool.

 

[brentc]

no, but maybe.... ill try and see. cant hurt. ive been using cci but ill throw in some federal 210s.

My best results have been with 210s in my two PRCs. I assume you've cleaned it?

 

[mountaincarver]

My best results have been with 210s in my two PRCs. I assume you've cleaned it?

yea, and its been very good as far as not fouling with copper. can you actually see a difference with primers? im gonna see if I can make it out this evening with 210s. you know, I even changed the scope out here a while back. what im not sure of (because I have no experience with em) is if this chasis design is as accurate as a traditional. the only other thing I can think of is bullet quality in this lot. they do fit the lands a little different from the previous lot in the fact the bullet measures the same length base to tip and base to ogive (Hornady tool) but when measuring the lands with them, they will protrude out of the case .023 more than last lot.

 

[brentc]

yea, and its been very good as far as not fouling with copper. can you actually see a difference with primers? im gonna see if I can make it out this evening with 210s. you know, I even changed the scope out here a while back. what im not sure of (because I have no experience with em) is if this chasis design is as accurate as a traditional. the only other thing I can think of is bullet quality in this lot. they do fit the lands a little different from the previous lot in the fact the bullet measures the same length base to tip and base to ogive (Hornady tool) but when measuring the lands with them, they will protrude out of the case .023 more than last lot.

Primers make a difference. I always test for best primer. The different bullet dimensions will absolutely make a difference and I think there is a good chance that's why you gained a few tenths on your group size.

I recently cracked open new box of 147s and noticed a little different performance, but I too had switched optics on both rifles. I guess I'll have to check the distance to the lands with my new box of bullets.

I've since developed a load with 140 Elites that looks promising. I'm going to test it tomorrow with different brass weights to see how the weight variance affects performance.

 

[mountaincarver]

Primers make a difference. I always test for best primer. The different bullet dimensions will absolutely make a difference and I think there is a good chance that's why you gained a few tenths on your group size.

I recently cracked open new box of 147s and noticed a little different performance, but I too had switched optics on both rifles. I guess I'll have to check the distance to the lands with my new box of bullets.

I've since developed a load with 140 Elites that looks promising. I'm going to test it tomorrow with different brass weights to see how the weight variance affects performance.

the elites definitely have the edge in mine. the absolute best accuracy node my rifle will shoot them is in the lower 2900s where the 147s come in a little faster. im debating between best accuracy or more weight and bc. thanks for the input, I appreciate it. When testing for primers, I assume you try different ones after finding the best load?

 

[brentc]

the elites definitely have the edge in mine. the absolute best accuracy node my rifle will shoot them is in the lower 2900s where the 147s come in a little faster. im debating between best accuracy or more weight and bc. thanks for the input, I appreciate it. When testing for primers, I assume you try different ones after finding the best load?

I have the 140s going 3055 fps in my Ridgeline with 56.8 grains of RL26 primed with a 210M seated at 2.970 OAL. (.070" off). My first test had five into 1/2 MOA group at 100, so I loaded another 5 rounds for velocity and range validation at 600. The first three shots were single digit ES over the Magnetospeed and the next two landed an inch apart at 600 yards.

 

[brentc]

When testing for primers, I assume you try different ones after finding the best load?

Yes, last step to ensure I'm getting the best result with groups and ES/SD unless I'm confident I can't improve. For me, it's either Feds or CCIs. I have Win primers on the shelf, but they rarely make the final cut.

 

[mountaincarver]

I have the 140s going 3055 fps in my Ridgeline with 58.6 grains of RL26 primed with a 210M seated at 2.970 OAL. (.070" off). My first test had five into 1/2 MOA group at 100, so I loaded another 5 rounds for velocity and range validation at 600. The first three shots were single digit ES over the Magnetospeed and the next two landed an inch apart at 600 yards.
View attachment 119871

That's good! Interesting on the speed. i couldn't begin to put that much rl 26 in mine. once seasoned, mine was running the 140s at 3160 at around 56 grains of rl26. sticky bolt. looking through my data, h1000 pushes them almost 3200 with 58.8 grains. crazy. when new, i was getting about 3030 with same load. now my h1000 accuracy node is just under 55 grains. h4831 with 147s went from 53.8 to just under 52. never had a barrel change so much; hopefully it is settled down for a while.

 

[brentc]

That's good! Interesting on the speed. i couldn't begin to put that much rl 26 in mine. once seasoned, mine was running the 140s at 3160 at around 56 grains of rl26. sticky bolt. looking through my data, h1000 pushes them almost 3200 with 58.8 grains. crazy. when new, i was getting about 3030 with same load. now my h1000 accuracy node is just under 55 grains. h4831 with 147s went from 53.8 to just under 52. never had a barrel change so much; hopefully it is settled down for a while.

58.6 is a lot. My load is actually 56.8. I hate it when I transpose numbers. I need to be more careful.

Another thing I've noticed. Your velocities are way higher than I've seen in my Ridgeline and MPR with similar charges. Have you verified your chronograph?