hard extraction

[Hman1956]

Hi Guys,
I would just like to start with the fact that I did spend 2 nights looking in the old archives before posting this question.
so here goes, this is a brand new build for me, and my first.
300 RUM Match chamber in a McGowen RemAge barrel. Rem700LA trued.
the brass is new Norma with the necks turned to .0115=.330 loaded.
trimmed and checked against the chamber drawing. Headspace is correct and there is no growth on the fired cartridge.
loaded with 87gn. of Re-22 pushing a 178 HPBT.

I'm having hard bolt lift and extraction, but not on every round. I would say maybe 50% of the time.
I do see some frosting on the brass after firing and looks like a rough chamber is the cause. it goes all the way around the cartridge with some non-frosted bands also. you can see it but not feel it.

Bill Hodkinson

 

[Dusty Stevens]

Bad chamber it seems to me or polished wrong if you have those frosted bands. Not sure where they get their steel from but it could be that. It could also be a misaligned boltface on the trued action. Theres just too many variables on this

 

[Hman1956]

didn't think about the bolt face.....I'll take the barrel off tomorrow and blue dye the face and rub the cutter at it again. I can't remember If I did the lugs first or the bolt face. But I do remember that the lugs were full on one side and almost nothing on the other.

Bill Hodkinson

 

[Don]

.

Borescope the chamber, show us photo's of the frosted brass and chamber, otherwise it will be just speculation and wild ass guesses as to the cause of hard extraction.[SUP][/SUP]

 

[Hman1956]

I don't have a bore scope but here are 2 pictures




thanks and have a great Thanksgiving

Bill Hodkinson

 

[CMaier]

extractor to groove interference ?
put a case in the bolt, out of the action and and see
if you can rotate a case in place against the ejector.
or remove the ejector first.

 

[Don]

I don't have a bore scope but here are 2 pictures
View attachment 17066
View attachment 17067


thanks and have a great Thanksgiving

Bill Hodkinson

Brass does not look too bad, I would not be too worried about the frosted look areas, I would be more concerned about the cyclindrical patterns displayed just past the extractor groove and just before the shoulder/body junction on the brass body, I would do a moderate polish to the chamber
until those cylindrical patterns were reduced and then retest for proper extraction................Don

 

[Dusty Stevens]

Thats just a bad chamber. Those rings are from not clearing chips

 

[Hman1956]

extractor to groove interference ?
put a case in the bolt, out of the action and and see
if you can rotate a case in place against the ejector.
or remove the ejector first.

no problems there, case turns ok.


Bill

 

[Hman1956]

Brass does not look too bad, I would not be too worried about the frosted look areas, I would be more concerned about the cyclindrical patterns displayed just past the extractor groove and just before the shoulder/body junction on the brass body, I would do a moderate polish to the chamber
until those cylindrical patterns were reduced and then retest for proper extraction................Don

ok, the best way of doing that without a lathe?

Bill Hodkinson

 

[Hman1956]

Thats just a bad chamber. Those rings are from not clearing chips

But would that cause the extraction problems?
when I was looking thru some of the old posts about extraction problems I found a few that talked about some brass Mfg. have smaller base Dia.
and when they switched brands the problems went away.

your thoughts on that?

Bill Hodkinson

 

[243winxb]

300 RUM at 65,000 psi is going to be hard to extract from that chamber. Reduce load or try to polish chamber.

 

[Steelhead1]

In looking at the pictures, it would appear that during the neck turning, you did not turn the neck far enough down to the shoulder junction! It actually looks like there is/ are two ridges towards the base of the neck. This could bedue to the glareon the photo, but is it possible that if those are ridges, could that cause the hard bolt lift and opening?

 

[Dusty Stevens]

But would that cause the extraction problems?
when I was looking thru some of the old posts about extraction problems I found a few that talked about some brass Mfg. have smaller base Dia.
and when they switched brands the problems went away.

your thoughts on that?

Bill Hodkinson

Yes. I just had 3 5r remington 300wm rifles come in in the last month. All had to be beat open with a mallet. Now after crosshatching the chamber like it should be theres no issues at all and the brass looks perfect. They had frosting right above the belt on the brass and the chambers looked like a mirror- cut with a dull reamer that just pushed the metal. All good now i test fired all 3 and all 3 killed deer already.

 

[Hman1956]

In looking at the pictures, it would appear that during the neck turning, you did not turn the neck far enough down to the shoulder junction! It actually looks like there is/ are two ridges towards the base of the neck. This could bedue to the glareon the photo, but is it possible that if those are ridges, could that cause the hard bolt lift and opening?

when I first turned the necks it was correct ( all the way to the shoulder) what you are seeing is the neck after sizing .328 Vs .334 of the unsized part. (the chamber is .334)


Bill

 

[dk hunt 14]

I would think R22 is too fast a powder for that case. I would think H1000, 7828 or Re 33 would be better. If the chamber was done with a tight reamer maybe your die isn't sizing enough at the back end of case. Matt.

 

[B.Larson]

Thats just a bad chamber. Those rings are from not clearing chips

I agree................. +2