carbon on necks, sticky bolt

[ishootkittens]

Hey guys, been a while. Spending more time shooting than posting!

I've got a bit of a problem and you guys have always helped in the past. I finally finished my 300 norma and I am working up some loads. The rifle shoots great to the point where I can't tell Mich difference in accuracy from load to load until I hit the extremes. I started at 83gr and loaded all the way up to 88. I have heard guys going as high as 90 but I am getting sticky bolt lift and a thick black carbon build up on my necks on EVERY load.I've heard the black carbon marks could be from light loads but as I start to build up to 86-87gr I begin to get slight extractor marks.

Any help would be appreciated.

 

[Pdvdh]

Tell us which primer, powder, and bullet weight you're shooting.

 

[TackDriv3r]

Sounds like High pressure when you have extractor marks. Are the primers flattened?

 

[ishootkittens]

83-88gr of retumbo
Norma cases
Federal champion lrm primers
230 berger hybrid

I've heard that the black carbon is low pressure or not a good neck seal. Thanks guys

 

[ishootkittens]

And no. Primers look good throughout all loads slight extractor Mark on head when loaded to 87+

 

[Pdvdh]

Excess carbon on the exterior of the case necks, I presume? You've used Retumbo on other cartridges and now notice much more carbon fouling with your 300 Norma?

 

[ishootkittens]

I've never used retumbo on any other cartridges but of all other cartridges I shoot, this carbon seems excessive. If i could just find some load data somewhere to compare too. Most load data I have found matches up pretty well with what I'm using. I'm just confused as to why the stiff bolt. the bolt lifts very easy til I come the the very top of the lift then I have to "pop" it open with a slap of my palm.

 

[Pdvdh]

Maybe a gunsmith can comment on the lifting of the bolt, if you describe which action you're using. Could be something unique to your brand/model action.

It does sound like you're hitting max pressure if you're seeing evidence of brass flow on the case head, and ALSO experiencing stiff bolt lift at the same time.

I'd shoot those loads over a chronograph/magnetospeed, if you know anyone that has one. See where your MV is at. If you're at max pressure, your MV should be very healthy for your barrel length. Then it could simply be your barrel/chamber pressures out sooner than average. If that's the case, it sounds like you're getting good accuracy and... no undue worries.

 

[tbrice23]

I've never used retumbo on any other cartridges but of all other cartridges I shoot, this carbon seems excessive. If i could just find some load data somewhere to compare too. Most load data I have found matches up pretty well with what I'm using. I'm just confused as to why the stiff bolt. the bolt lifts very easy til I come the the very top of the lift then I have to "pop" it open with a slap of my palm.

Retumbo is very dirty.
The first time I used it I thought I was doing something wrong too.
Black soot filth on the necks, regardless of the load density or primer used.

 

[tbrice23]

If it bothers you try H1000, the cleanest burning powder in that burn range (at a decent load density) ,IMO.
It's so clean in fact that I don't like to use it in one particular barrel because it just wont foul quick enough for me to 'settle' the barrel when its squeaky clean.
Otherwise, most of my other barrels love it.

 

[ishootkittens]

Well that makes me feel better. I didn't realize it was so dirty. Maybe I should just check with the usual pressure marks. I do see sleigh extractor marks around 87 and I'm using a strong BAT action.

 

[WildRose]

Before shooting it again I think I'd have a gunsmith look at it. The carbon on the outside of the case neck can be an indicator of several things none of which are good.

Your necks may be too long, this can cause extreme pressures by crimping the neck against the bullet.

It could also be a head space problem.

Either of those can cause you some catastrophic problems if you keep shooting.

 

[toliver]

If the bolt lifts easily then needs a little more pressure at the end with a click at the top is often a slightly tight chamber. How many times was the reamer used? Or often the sizing die isn't effectively sizing the body well down near the web. Other than that it warrants getting looked at with extractor marks. Bring fired case and gun to a smith.

 

[WAMBO]

I've experienced the same issues with Retumbo, not my favorite powder as I prefer H1000 which to me burns cleaner and pressure doesn't spike as quickly as Retumbo but you will give up some velocity.