Over Pressure

[Jud96]

I just used this method.

I did this with every bullet I loaded in my 308 win and was a considerable amount off from what I thought was the lands with what this showed me.

I use this exact same method. It definitely is more accurate for me and it showed me just how far in or off the lands I was using other methods.

 

[live2huntmt]

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.

 

[Mram10us]

For a carbon ring, spin a 338 brush in the neck area with carbon remover than patch it out to see. Borescope ($50) would help down the road

 

[live2huntmt]

For a carbon ring, spin a 338 brush in the neck area with carbon remover than patch it out to see. Borescope ($50) would help down the road

Nylon or brass brush? I usually only clean with nylon.

 

[Jud96]

How long of a barrel do you have? Nosler shows 91.5gr as max with a 200gr going 3070FPS in a 24" barrel. If you're getting 3140 with 89.0gr then I'd say that's probably your max load. Sometimes you can get over book max and be okay, sometimes you can't get to the book's max.

EDIT: I saw where Hodgdon data shows 95.5gr as max. Sierra shows 88.7gr as max with their 200gr bullets. If Nosler says 91.5 is max and Sierra shows 88.7 as max, then I'd be cautious on Hodgdon's data. If I'm loading for a new to me cartridge that has load data, I check 3-4 sources and then average the max load shown. I'd rather be safe than sorry.

 

[MagnumManiac]

How do you get book velocities with a barrel 2" longer than the test barrel?
It ain't ever gonna happen...this is WHY you are running faster than book.

Also, extruded primers are nearly always a firing pin hole or spring problem, only when lots of other signs are present all at once is this an issue.

Have you had hard extraction or sticky bolt lift? I do not mean a 'clicker' right at the top either, I mean right from lifting the bolt.

Some brass which is soft, will show ejector marks even with start loads...so this may be your issue. Also, some plunger springs are too stiff and long and the brass has to fill the area.

There are many variables to consider.

Cheers.

 

[Bdubose]

Just started loading for my 300 RUM and I'm finding the same thing with the 210 ABLRs.
I shoot the 168 ABLRs in my 7 mag and it likes them at .120 jump & sub MOA out to 600.
Backing off a bit may bring the pressures down, and it does not seem to hurt accuracy.

 

[Verminator2]

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.

 

[NW Hunter]

Thanks. I am running a Wyatts extended box in it because my other load is 230 Berger OTM Tactical & RL33. I was getting 3040 FPS w/ 94.9gr of RL33 @ 3.815" (.006" jump) and slight pressure signs

I would recheck your CBTO of your Berger OTM 230's.
If your recheck shows a measurement LESS THAN 3.815" ( your original measurement), that is an indicator that a carbon ring is in the throat.

 

[Indian7953]

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 have a Christian arms in a 7rem mag that I use Retumbo in. I have to keep it 2 1/2 gr. less than Max book or I have Wayover pressures, but I still have faster velocity then book, so I just load it down and it worked great.

 

[live2huntmt]

For a carbon ring, spin a 338 brush in the neck area with carbon remover than patch it out to see. Borescope ($50) would help down the road

Where can I get a $50 borescope?

 

[JMW67]

Where can I get a $50 borescope?

amazon I bought the teslong and have been happy with it

 

[Joe ziz]

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'll speak having knowledge of the CA ridgeline because I have one. It is very common in the CA mag calibers to get the 2 ejector imprints on the case. I've loaded using 5 different powders on all spectrums of the books and almost everyone will produce ejector imprints. I find my most accurate powder being Retumbo and next best R33. There is a Facebook page for Christensen arms owners thats pretty informative.

 

[jrg]

Where can I get a $50 borescope?

You can get it here; https://www.amazon.com/s?k=teslong+...4M&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!