Over Pressure

[Shane Lindsey]

That's three posts with Christensen barrels that seem to pressure up fast...Sounds like they have tight bores!!!???

 

[MTGEEZER]

My experience with carbon rings is that you have to use a proper procedure with the proper compound to have any hope of getting it out. Standard cleaning practices wont remove it.

Also, if your 230 load was towards the upper end, you should see the pressure effects of a carbon ring on it too. Try a couple rounds of that and see if it shows hotter signs than it used to.

I use a tight patch with simichrome and work the neck throat area in short strokes and spinning. It will always come out black. If you decide it's not a carbon ring, its really likely it's one of the other things suggested here. You may just have a fast barrel.

Food for thought: I, too, run a Christensen (6.5prc) and have found after working up loads with 5 different bullets using multiple powders and primers that I always reach pressure long before the bullet manufacturer's stated maximum charge and, I jump every bullet. 2 of these loads (1mono and one bonded), shoot half inch @ 100 on my "good" days. Since you and another poster seem (at least to me) to be experiencing the same issue as I with the Christensen, which I actually do like alot, could it have something to do with chamber and bore dimensions being tight, as suggested earlier? Any other CA shooters out there with same issue? Stay safe and God bless you all! MTGEEZER

 

[live2huntmt]

You can get it here; https://www.amazon.com/s?k=teslong+borescope&crid=33CD8S68CXZ4M&sprefix=teslong,aps,178&ref=nb_sb_ss_i_3_7
I have one & you simply can't beat it for the price, great clear picture, will also connect to your computer!

Any reason to buy the $90 one over the $50 one?

 

[Verminator2]

Food for thought: I, too, run a Christensen (6.5prc) and have found after working up loads with 5 different bullets using multiple powders and primers that I always reach pressure long before the bullet manufacturer's stated maximum charge and, I jump every bullet. 2 of these loads (1mono and one bonded), shoot half inch @ 100 on my "good" days. Since you and another poster seem (at least to me) to be experiencing the same issue as I with the Christensen, which I actually do like alot, could it have something to do with chamber and bore dimensions being tight, as suggested earlier? Any other CA shooters out there with same issue? Stay safe and God bless you all! MTGEEZER

MT,

Entirely possibly. I just wanted to offer more information on carbon rings, if that was in fact the case.

 

[NW Hunter]

Any reason to buy the $90 one over the $50 one?

The $90 Teslong has a bore rod with the camera attached to the end.
It makes it easy to rotate the god in your bore to get a 360 degree view.

 

[MTGEEZER]

MT,

Entirely possibly. I just wanted to offer more information on carbon rings, if that was in fact the case.

Got it. Scrubbed the ring out of 3 other guns a few days ago. I will scope the 6.5 now, too, even though I am eager to test this "last" load using RL 26 which I finally got a bunch of.

 

[jrg]

Any reason to buy the $90 one over the $50 one?

I own the $50.00 borescope & it does everything I want, You really are just guessing what your barrel looks like if you don't use a borescope. Best money I ever spent!

 

[live2huntmt]

I own the $50.00 borescope & it does everything I want, You really are just guessing what your barrel looks like if you don't use a borescope. Best money I ever spent!

I just ordered the one with the rod! I'm excited to get it!

 

[jrg]

I just ordered the one with the rod! I'm excited to get it!

You are going to love it!

 

[freddiej]

live2huntmt, There are a few reasons for your over/high pressure signs at such a low powder charge.
#1 is a min or close to min SAAMI chamber. a pair of calibers will show you how big your chamber is.
#2 Hot powder batch
#3 carbon ring
#4 your brass' necks are all too long, but that is normal from what I have seen with once fired resized brass. Especially, in 223/5.56. Some of them grew 0.030" (over max) from the initial firing to resizing. My 300 W/M had an average stretch from virgin case to once fired was 0.018"(over max). I would grab the calibers and measure them brass.
I suspect #4 or #1 are your problem.

 

[robert l]

I just started developing a load for a CA Ridgeline 300 RUM with 200gr AccuBonds jumping .020" and Retumbo in 1x fired Norma brass and Fed215 primers. I am way below book charge weights and way over pressure and high velocities. This is a new keg of Retumbo...do you think it's just a really hot lot #? Even 89.2 grains is flattening primers, cratering around firing pin, showing both ejector circles, and clicking at the top of my bolt lift. Is there anything that could be causing this other that really hot powder?

The blue line is an average between the two test rounds at each charge weight.View attachment 187933

I had some thing near that but it was my fault .Because i did not back off the charge on new adg brass like it says to do.So i ended up with pretty much the same issue. I know its not the same but there may be some thing in there that may help,bob.

 

[live2huntmt]

live2huntmt, There are a few reasons for your over/high pressure signs at such a low powder charge.
#1 is a min or close to min SAAMI chamber. a pair of calibers will show you how big your chamber is.
#2 Hot powder batch
#3 carbon ring
#4 your brass' necks are all too long, but that is normal from what I have seen with once fired resized brass. Especially, in 223/5.56. Some of them grew 0.030" (over max) from the initial firing to resizing. My 300 W/M had an average stretch from virgin case to once fired was 0.018"(over max). I would grab the calibers and measure them brass.
I suspect #4 or #1 are your problem.

My 1x fired and sized brass length is 2.845". My 2x fired unsized brass length is 2.847". I do think my chamber is very close to min saami dimensions.

Even my 87.5gr loads primers are still cratering around the firing pin but not showing ejector marks or heavy bolt lift...I think I need to send my bolt into Long Rifles Inc and have them install a striker pin bushing.

 

[Mram10us]

I might have missed it, but have you verified no carbon ring?? That said, those are fast speeds for the charge

 

[John 264]

Update: I stripped the bore down to bare metal. Not sure about a carbon ring because I don't have a borescope. Went to the range and fired 3 rounds to foul the clean barrel. Shot 3 more with 89.0gr of Retumbo and still showed over pressure and had the same velocity as before if 3147fps. I then shot 3 more of 89.0gr but seated .030" deeper, jumping.050"...showed slight pressure signs and produced 3122 fps.

So I don't think it was a copper fouling issue, and I don't think I was seating into the lands. Next step, I am going to try different primers. I wish I could find a different lot of Retumbo to see if that would change anything.

it is the accubond they have a thicker jacket and build pressure that you don't get with the burger mabe you should try the 200 gr hybrid target or the 200.20x hybrid target