Flattening every single primer unless I run a very slow load

[AnimalMother224]

my 65CM (Curtis action /xcal barrel) match chamber has flattened 210M, 215M, 250's, BR2s. with every powder combination I can throw at it and Ill get sticky bolts and ejector marks at modest velocities

Ive tried H4350 (which is supposed to be the best powder in the world for this round), SW Precision, RL16, RL17 with bullets ranging from 120 to 140 class.

I get the most amount of pressure signs with H4350 with 140 class bullets but can't go over 2740fps, I can get better speeds with lighter bullets but the pressure is still right there.

RL16 is better with more respectable velocities respectively

seating .030 to .080 OTL.

Am I just handcuffed with this chamber? its disheartening H4350 is "too fast" for my gun.

I was getting. carbon ring and copper fowling problems so I strip cleaned the gun and the pressure problems got better. think I might be do again for another cleaning

but on average the pressure has always been on the high side on the gun no matter what

 

[morganlamprecht]

make sure you have plenty neck clearance with your brass

that will cause case pressure signs across the board if its not adequate

 

[918v]

make sure you have plenty neck clearance with your brass

that will cause case pressure signs across the board if its not adequate

+1

And make sure you are not bumping the shoulder back too much.

 

[straightshooter1]

. . . and make sure to keep carbon ring build up out of the picture.

 

[AnimalMother224]

+1

And make sure you are not bumping the shoulder back too much.

I bump 2 thou from fired. ive tried two difference dies.

 

[AnimalMother224]

make sure you have plenty neck clearance with your brass

that will cause case pressure signs across the board if its not adequate

are you referring to neck tension? I run a mandrel down to 1thou tension

if your talking length, they are all shorter than max length but I did just run a bunch so they are all the same.

Diameter wise Im not sure, I can chamber a dummy load without the firing pin and ejector and it goes In and comes out fine. and the fired cases carbon ring on the case neck is equal all around the circumference around the neck.

 

[morganlamprecht]

2 thou from fired works so long as the brass was fully formed to begin with...if the brass starts out say .008 short new, and only expands .004 on the first firing, then .002 puts you back at .006 setback

seen many reloaders overlook this, split cases follow up in short order

 

[AnimalMother224]

. . . and make sure to keep carbon ring build up out of the picture.

im going to scope it tomorrow and check it. Im right at about 300 rounds from the last deep cleaning

 

[morganlamprecht]

are you referring to neck tension? I run a mandrel down to 1thou tension

if your talking length, they are all shorter than max length but I did just run a bunch so they are all the same.

Diameter wise Im not sure, I can chamber a dummy load without the firing pin and ejector and it goes In and comes out fine. and the fired cases carbon ring on the case neck is equal all around the circumference around the neck.

a loaded round neck vs the chamber neck diameter

there are 2, 308win reamers at the shop...1 of them is a "match" with a tighter neck, i dont remember the spec off hand, but it will give pressure signs with fed, lapua, prime, or lake city brass (all ive seen used)...if the brass isnt turned for clearance...it will all chamber fine, but theres not enough room with the brass to release the bullet in a normal fashion

the other reamer has a neck diameter a few thou larger and you can run any normal/hot 308 loads in it just fine

 

[AnimalMother224]

2 thou from fired works so long as the brass was fully formed to begin with...if the brass starts out say .008 short new, and only expands .004 on the first firing, then .002 puts you back at .006 setback

seen many reloaders overlook this, split cases follow up in short order

thats a good point.. its 3rd firing on star line, but this was happening with the Hornady factory brass I was reloading ... currently im taking the fired brass, measure it, chamber it without the firing pin and ejector, bolt has to be pushed down, I size it with the +10 shell holder, measure it with no change, chamber with no change, put the +8 shell holder, size it, measure and shows a .0025 bump and it chambers perfect with a bolt handle falls. and I size to that. so I shouldn't be bumping too far.

 

[AnimalMother224]

a loaded round neck vs the chamber neck diameter

there are 2, 308win reamers at the shop...1 of them is a "match" with a tighter neck, i dont remember the spec off hand, but it will give pressure signs with fed, lapua, prime, or lake city brass (all ive seen used)...if the brass isnt turned for clearance...it will all chamber fine, but theres not enough room with the brass to release the bullet in a normal fashion

the other reamer has a neck diameter a few thou larger and you can run any normal/hot 308 loads in it just fine

the barrel is lazered "Match chamber". its possible its a tight neck? my star line neck thickness is .0135

that would be the most sense now that you mention it.

when my carbon ring was going unchecked, I realized it by two things. chambering a loaded round and failure to extract, the carbon ring was sticking the bullet .. and then I was getting stuck case issues. and the carbon ring wasnt awful compared to some examples ive seen .. so a tight neck with minimal carbon ring would show pressure signs when there really shouldn't be with a modest load

from a fire case, I can push the bullet down through the neck but it doesn't fall through

 

[918v]

are you referring to neck tension? I run a mandrel down to 1thou tension

if your talking length, they are all shorter than max length but I did just run a bunch so they are all the same.

Diameter wise Im not sure, I can chamber a dummy load without the firing pin and ejector and it goes In and comes out fine. and the fired cases carbon ring on the case neck is equal all around the circumference around the neck.

What is your fired neck diameter? What is your loaded neck diameter?

 

[TxWelder35]

How are you cleaning your brass after you size it to get the lube off?

If their is ANY lube in the brass still when you shoot it there will be high pressure signs.

I tumble my brass after sizing to make sure all the lube is removed from the cases

 

[morganlamprecht]

.0135 necks shouldnt be causing issues in any normal-ish 6.5 creed chamber, but who knows, ive seen some weird things out there lol

all of my 6.5 stuff is .296-.297 neck...loaded rounds are .291-.292

 

[AnimalMother224]

How are you cleaning your brass after you size it to get the lube off?

If their is ANY lube in the brass still when you shoot it there will be high pressure signs.

I tumble my brass after sizing to make sure all the lube is removed from the cases

yes. my final step is to dry tumble to clean off all lube

 

[AnimalMother224]

What is your fired neck diameter? What is your loaded neck diameter?

I can't remember off the top of my head ill take some measurements when I get home in the morning. I know my loaded is .291/.292

 

[Jskmtd]

What should the difference be between a loaded neck diameter and a fired neck diameter?

 

[never_summer]

Depends on the chamber and spring back, but I’m sure he’s asking to make sure the chamber isn’t too tight and he’s not seeing like .001” difference or the same reading.
Some bench rest guys run very tight on the neck clearance. I neck turn .005” clearance to allow for field match conditions

 

[Jskmtd]

I'm only seeing .002" difference between a loaded neck diameter and a fired neck diameter, so should I be turning the necks for more clearance? I'm also seeing pressure at a low powder charge for the cartridge.

 

[never_summer]

I’ll let some of the other guys with more experience answer that one, but there are multiple variables that could cause pressure signs on a moderate charge. With .002” of neck clearance you have .001” on each side which is pretty tight but you could have some spring back also.

 

[308sako]

What is your barrel length and are you using a suppressor? Dwell time might be a part of apparent pressure.
Second ? Is what charge weight of H4350 with 140 weight bullets?

 

[spife7980]

I'm only seeing .002" difference between a loaded neck diameter and a fired neck diameter, so should I be turning the necks for more clearance? I'm also seeing pressure at a low powder charge for the cartridge.

What are those actual measurements though?

 

[Nimothy]

Is this an mpa factory rifle? These problems seem familiar.

 

[mick243]

yes. my final step is to dry tumble to clean off all lube

please tell me you are tumbling after resizing, not tumbling whole loaded rounds....

 

[AnimalMother224]

please tell me you are tumbling after resizing, not tumbling whole loaded rounds....

yes. sorry if that sounded like anything other than tumbling after sizing.. to be very clear no case lube has ever touched my chamber.

im curious if the tumbling dust is adding a "dry lube" to the outside of the case and creating a situation where my brass isn't grabbing the chamber wall

 

[AnimalMother224]

Is this an mpa factory rifle? These problems seem familiar.

@Nimothy
IT IS!!!!!!!!!!!!!

 

[AnimalMother224]

What is your barrel length and are you using a suppressor? Dwell time might be a part of apparent pressure.
Second ? Is what charge weight of H4350 with 140 weight bullets?

no suppressor. I live in a communist state

26" M24

40.4grains, 2730fps avg. doesn't matter if im jammed, or .050" OTL. (.050 is where she likes 140 ELDs)

and thats in hornday factory brass and SL fire formed brass.

 

[AnimalMother224]

What is your fired neck diameter? What is your loaded neck diameter?

@918v

fired, consistent measurements is .295
and double checked loaded is .291/.292

 

[918v]

Although you have plenty of clearance, you have a tighter chamber than most. This will increase pressure over a looser chamber and will require a powder charge reduction. That’s the cost of running a tight chamber.