PWS frustration

[wvfarrier]

I have been working on some reloads for my PWS MK218. These are 168 grain TTSX using LC brass. All full length re-sized. The brass drops cleanly in and out of my gauge. They also chamber cleanly in my Big Horn 308 and Aero AR10. However, they will NOT fully seat in my Mk218. I am totally perplexed as factory ammo works fine. I took measurements and my ammo matches the factory in diameter at the neck, shoulder and base. Thoughts?

I am an experienced reloader but have not encountered this before.

 

[TheOfficeT-Rex]

How far back did you push the shoulders?

 

[264win]

It sounds like a length issue, brass length or bullet seated out to far ( for that particular chamber)

 

[themightytimmah]

Did you try blackening the case and bullet with a permanent marker and trying to chamber it, the marker should wipe off where the issue is and that will help to narrow it down.

What’s your seating depth vs factory?

 

[M4orturnate]

Make sure your not jamming the shit out of the bullet. Look for marks on it. Could also be sized to long as other say. If you have any fires brass out of that chamber use it for measuring

 

[wvfarrier]

Did you try blackening the case and bullet with a permanent marker and trying to chamber it, the marker should wipe off where the issue is and that will help to narrow it down.

What’s your seating depth vs factory?

I did but it shows the rifling marks pretty far forward. My OAL is 2.80" as these were starter loads for my ladder tests.

If its a "shoulder issue", it should not fit my case guage, correct? Maybe I should fire a factory load and check the shoulder on it......

 

[DocRDS]

I'd go to the saami specs and measure everything. Don't forget that many cartridges has a slight "taper" (notice base is .4709 while the "top" is .4539) so the base measurement may not be enough. I don't trust my guages much as unless its a full "squish" on the reload, rounds don't fit.

I don't have a solution except a Bill Clinton "I feel your pain" Mine was a resizing issue, never did quite figure out what dimension it was.

Fuck also forgot spitball idea--there is a "slight" (I think) chamber difference between 7.62 Nato and 308 Win. Could be totally wrong, but worth checking

 

[Mike Casselton]

Take one cartridge and seat the bullet down to 2.750 and see if it chambers. If it doesn't, seat it to 2.700 and try again.
If that doesn't chamber, then it's a brass sizing issue.

 

[Mike_in_FL]

Where did you get your LC brass? I've had problems with processed stuff if it wasn't run through a small base sizer as it seems safe to say it would've been fired out of machine guns. For that matter I've seen problems buying LC primed/pulled cases where they've stretched the neck pulling the bullet.

I'm not saying to buy Lapua brass to use in a gas gun but sometimes it's easier to use other brass than deal with LC 7.62.

 

[Evintos]

PWS uses 308 match chamber specs, not a standard 308 SAAMI spec. It being a match chamber would give you the results you're having now which is your load fitting in the case gauge and other 308 win chambers but not in the PWS. Try bumping the shoulder back some more.

Example if you normally bump .002 to .003, aim for .004 to .006 bump with the PWS, might even have to set the shoulder back more since there is no real "308 match" chamber standard. If you have a headspace comparator, you'd be able to measure it and set the bump based off the once fired without the guess work.

 

[XP1K]

I've got an mk216 and I've never run into this issue. If you're getting marks on the bullet like it's jamming into the lands at 2.8" I'd be leaning towards a chamber issue. That doesn't explain how it shoots factory ammo just fine though.

I know sizing my cases from my 216 and my 700LTR, the fired cases from the 700 take a little more effort on the press.

I've never loaded the ttsx. All mine has seen is smk's, Amax, eld-m/x, and a few 168 NBT.

I've had other issues with the gun but not reloading related.

 

[Frank Green]

PWS uses 308 match chamber specs, not a standard 308 SAAMI spec. It being a match chamber would give you the results you're having now which is your load fitting in the case gauge and other 308 win chambers but not in the PWS. Try bumping the shoulder back some more.

Example if you normally bump .002 to .003, aim for .004 to .006 bump with the PWS, might even have to set the shoulder back more since there is no real "308 match" chamber standard. If you have a headspace comparator, you'd be able to measure it and set the bump based off the once fired without the guess work.

What is a match chamber?

Tighter throat diameter? Shorter throat length?

No turn neck on the brass?

Tighter diameters on the case body of the chamber?

If PWS is running a tighter chamber (lets just assume on the case dimensions of the chamber or headspace and will exclude the throat area for now) your asking for problems.

A chamber print of what they chambered the barrel with would help if the OP can obtain one. With out it we're guessing as to what the chamber spec is/was suppose to be made to.

Does it happen with box ammo? If the answer is no... then I'll say you have something going on with your reloads and that's where you have to look. If you have chambering issues with new box ammo.... then it's something up with the gun/chamber.

Can the OP check the headspace of the gun with a set of headspace gauges? I've seen more than one gun where the chamber wasn't cut to spec and even in cases where a roughing reamer was used and the gun would headspace but it wouldn't chamber ammo. Just fixed a gun last fall for a customer where the gunsmith used a roughing reamer and never finished reamed the chamber with a finish reamer.

Later, Frank
Bartlein Barrels

 

[918v]

I have been working on some reloads for my PWS MK218. These are 168 grain TTSX using LC brass. All full length re-sized. The brass drops cleanly in and out of my gauge. They also chamber cleanly in my Big Horn 308 and Aero AR10. However, they will NOT fully seat in my Mk218. I am totally perplexed as factory ammo works fine. I took measurements and my ammo matches the factory in diameter at the neck, shoulder and base. Thoughts?

I am an experienced reloader but have not encountered this before.

Where at the base are you comparing? Cuz very few dies reduce base diameter of a fired case back to factory.

 

[Frank Green]

To the OP...

Have you contacted PWS?

 

[XP1K]

I just emailed them about their "308 match" chamber. We'll see what tgey say. I think I have read somewhere in the past it was a ptg semi auto match chamber. Not entirely certain of that though.

 

[Evintos]

What is a match chamber?

Tighter throat diameter? Shorter throat length?

No turn neck on the brass?

Tighter diameters on the case body of the chamber?

If PWS is running a tighter chamber (lets just assume on the case dimensions of the chamber or headspace and will exclude the throat area for now) your asking for problems.

A chamber print of what they chambered the barrel with would help if the OP can obtain one. With out it we're guessing as to what the chamber spec is/was suppose to be made to.

Does it happen with box ammo? If the answer is no... then I'll say you have something going on with your reloads and that's where you have to look. If you have chambering issues with new box ammo.... then it's something up with the gun/chamber.

Can the OP check the headspace of the gun with a set of headspace gauges? I've seen more than one gun where the chamber wasn't cut to spec and even in cases where a roughing reamer was used and the gun would headspace but it wouldn't chamber ammo. Just fixed a gun last fall for a customer where the gunsmith used a roughing reamer and never finished reamed the chamber with a finish reamer.

Later, Frank
Bartlein Barrels

Therein lies the major problem with so-called "match chambers"; the lack of a "match" standard. I would even go as far as saying a commercially/publicly offered product in a 308 "match" chambering deviating from SAAMI 308 win min is problematic.

 

[hlee]

Chasing a similar problem is why I now run every piece of sized brass through my rifle before any reloading begins.

 

[wvfarrier]

Ok, so I ended up isolating it as the shoulder by comparing it to a piece of fired brass. Interestingly the brass will still not chamber unless I crimp the neck slightly.

 

[spife7980]

Ok, so I ended up isolating it as the shoulder by comparing it to a piece of fired brass. Interestingly the brass will still not chamber unless I crimp the neck slightly.

If thats true then your first statement where you compared the diameters was incorrect.
Share the actual measurements of factory, fired and sized. The answer is always there. Write them down and sharing em will always highlight what the conflict is.

I this example I was having issue with the base sizing, redding die i was using with the old barrel wasnt sizing old brass out of the old .472 chamber enough to fit in the new barrel, the forster die allowed it to by going an extra .001.

When comparing those above measurements to the brass after it has been fired from the .471 barrel it is clear that prior sizing of the base to only .471 wasnt small enough.

 

[XP1K]

This is what I got from PWS.

"We’ve used several over the years, some were specific 7.62x51 chambers, or standard .308 chambers, each has minuet differences. Our current .308 chamber reamer for the last 4 to 6 years has been a .308 MATCH II chamber reamer. This is actually a tighter chamber than most benchrest rifles use and is part of our 1 MOA accuracy guarantee with our rifles."


My 216 is a three shot wonder. Its not uncommon for the first three to go into half moa, but 4 and 5 usually open it up right at 1 moa.

 

[Hecouldgoalltheway]

I had one of these with the match chamber. Never had an issue with factory ammo or handloads. Someone already asked this question, but does it chamber and cycle factory ammo? If it does, something in your loading is obviously the problem. Then once you have a fired piece of brass, you should be able to reverse engineer the issue with your handloads with decent accuracy.

 

[wvfarrier]

No, my initial info was correct. However I purchased new RCBS dies yesterday at Sportsmans. I used it to bump the shoulder back and then resized.

 

[spife7980]

No, my initial info was correct. However I purchased new RCBS dies yesterday at Sportsmans. I used it to bump the shoulder back and then resized.

Ill just let you read what you wrote and let you explain how its correct if making a material change in the brass fixed it. If it didnt change the dimension in some way then you fucked up your measurement because it cant both be and not be.

I took measurements and my ammo matches the factory in diameter at the neck, shoulder and base. Thoughts?

Ok, so I ended up isolating it as the shoulder by comparing it to a piece of fired brass. Interestingly the brass will still not chamber unless I crimp the neck slightly.

 

[hlee]

Only fits if the neck is crimped? Check your case length. You may just need to trim the necks back a bit further.

 

[Frank Green]

This is what I got from PWS.

"We’ve used several over the years, some were specific 7.62x51 chambers, or standard .308 chambers, each has minuet differences. Our current .308 chamber reamer for the last 4 to 6 years has been a .308 MATCH II chamber reamer. This is actually a tighter chamber than most benchrest rifles use and is part of our 1 MOA accuracy guarantee with our rifles."


My 216 is a three shot wonder. Its not uncommon for the first three to go into half moa, but 4 and 5 usually open it up right at 1 moa.

If.....

tightening up the chamber area for the case dimensions is what is really done... your asking for problems.

So where was it tightened up? Again what is the definition of a match chamber here really mean.

Tightening up the chambers overall case dimensions... I've never really seen that do anything for accuracy in the grand scheme of things. The throat spec will make more of a difference.

 

[XP1K]

If.....

tightening up the chamber area for the case dimensions is what is really done... your asking for problems.

So where was it tightened up? Again what is the definition of a match chamber here really mean.

Tightening up the chambers overall case dimensions... I've never really seen that do anything for accuracy in the grand scheme of things. The throat spec will make more of a difference.

I agree. That wasn't as helpful as I had hoped.

I'm getting setup to do my first barrel for myself in 308. What's your favorite reamer for a 308 ?

 

[Frank Green]

I agree. That wasn't as helpful as I had hoped.

I'm getting setup to do my first barrel for myself in 308. What's your favorite reamer for a 308 ?

It's a modified 308win Obermeyer reamer with another +.020" to the freebore length. Works great with box ammo etc...print attached.

Standard case dimensions.

 

[XP1K]

It's a modified 308win Obermeyer reamer with another +.020" to the freebore length. Works great with box ammo etc...print attached.

Standard case dimensions.

Awesome! Thank you.