Stiff chambering

[jasonoldman]

Thanks for all the reply's so far. Tomorrow I will try to find some time to check some of your suggestions. I don't think I am doing any crimping but will double check to make sure. I use just a standard champher/debur tool. The press I am using is an RCBS one that a friend had sitting in a garage for years, and was rusted a little. I cleaned it up good but, will also check for slop in the press stroke. I will look and make sure everything is square as well.

As far as the brass sizing. I am bumping the shoulder .002" (according to hornady headspace kit). I measured the case necks and they were the same as factory loaded ammo that chambers easily. I only load .308 and 6mm cals so no mix ups. I will inspect the shoulders for buckling.

Thanks

 

[Joe King]

Originally I was wondering if you didn't get ahold of a bad run of bullets, unlikely though.

So here's what can be possible causes.
Bad press: out of alignment, excess wear, die mounting hole out of square.......

Bad dies: sizing die not square, expander ball pulling the case neck out of square, seating stem bent, seating die not square, wrong seating plug profile for bullets used.

or a combination.

If everything checks out have your rifle checked over by a gunsmith, could be a bad cambering job, unsquare bolt face.

Something is most likely out of square, these are the things I can think of right of the top of my head. Hope you get figured out to be an easy fix, and don't overlook operator error.

 

[jasonoldman]

Well I got a chance to look at everything again. Here is kind of a list of what I did and the result.

check the press for slack=good
check the press/dies for squareness = ok some slack in the threads causing a little causing a little unevenness. I think maybe a rubber o-ring to snug down onto.
Seated reloaded bullet deeper= still stiff bolt turn down
marked case at shoulder to check for shoulder issues = small rub on one side.
compared measurements from that reloaded stiff shoulder to sized brass that chambers clean = essentially the same.
reset seating die by putting usized brass in running press to the top, then I turned down the die till i felt light contact, backed out 1 full turn.

made sure the champher was pretty good on a couple of sized brass.
Seated a bullet = chambered smooth and easy
try again = same result.

Ok well may as well take out any other variables so I primed the case = stiff bolt close. Now this had me confused as it looked flush. Put back into hand primer and worked the handle while turning case. Now both rounds chambered smooth again. put a piece of paper on top of push rod and seated all primers in loaded rounds again. Most rounds started chambering smooth.

long story short. I will be much more maticulous on my reload process, and will be cleaning the primer pockets now (didnt worry about it before). I will also check squareness of my seating die when I get a chance, and leave the expander loose so it wont pull one way or the other. I still have some runout but more precise dies are a future project, and I will do what I can with what I have for now. Let me know if there is any other suggestions you have for me.

Thanks Again.

 

[Lefty7mmstw]

Well I got a chance to look at everything again. Here is kind of a list of what I did and the result.

check the press for slack=good
check the press/dies for squareness = ok some slack in the threads causing a little causing a little unevenness. I think maybe a rubber o-ring to snug down onto.
Seated reloaded bullet deeper= still stiff bolt turn down
marked case at shoulder to check for shoulder issues = small rub on one side.
compared measurements from that reloaded stiff shoulder to sized brass that chambers clean = essentially the same.
reset seating die by putting usized brass in running press to the top, then I turned down the die till i felt light contact, backed out 1 full turn.

made sure the champher was pretty good on a couple of sized brass.
Seated a bullet = chambered smooth and easy
try again = same result.

Ok well may as well take out any other variables so I primed the case = stiff bolt close. Now this had me confused as it looked flush. Put back into hand primer and worked the handle while turning case. Now both rounds chambered smooth again. put a piece of paper on top of push rod and seated all primers in loaded rounds again. Most rounds started chambering smooth.

long story short. I will be much more maticulous on my reload process, and will be cleaning the primer pockets now (didnt worry about it before). I will also check squareness of my seating die when I get a chance, and leave the expander loose so it wont pull one way or the other. I still have some runout but more precise dies are a future project, and I will do what I can with what I have for now. Let me know if there is any other suggestions you have for me.

Thanks Again.

Sounds like the high primers were it. Also watch you Winchester brass if you use any for shallow pockets that need to be reamed a bit deeper to be spec.. I have run into a few hundred on these lately. If a primer isn't .002" below flush it's not really deep enough. Some actions can either jamb(revolvers) or have mis-fires(semi-autos) on shallow primers. Bolt guns are more forgiving but high-primers can still mess with loc-time and ignition uniformity.
I would pull you bullets and powder before you re-seat primers. You can always run the case through the sizer again to get your neck tension up to snuff if you need to. Use a collet puller and you won't damage anything and all can be re-used.

 

[Sully2]

Ok well may as well take out any other variables so I primed the case = stiff bolt close. Now this had me confused as it looked flush. Put back into hand primer and worked the handle while turning case. Now both rounds chambered smooth again. put a piece of paper on top of push rod and seated all primers in loaded rounds again. Most rounds started chambering smooth.

long story short. I will be much more maticulous on my reload process, and will be cleaning the primer pockets now (didnt worry about it before). I will also check squareness of my seating die when I get a chance, and leave the expander loose so it wont pull one way or the other. I still have some runout but more precise dies are a future project, and I will do what I can with what I have for now. Let me know if there is any other suggestions you have for me.

Thanks Again.

I cant use any of those hand primer "machines". Arthritis!... I use a ram primer on the press but now use an RCBS primer tool with the long handle ( forget the name)..(RCBS automatic bench mounted priming tool)..

 

[Bart B]

If a primer isn't .002" below flush it's not really deep enough. Bolt guns are more forgiving but high-primers can still mess with loc-time and ignition uniformity.

Ignition uniformity; yes, sometimes a whole bunch; causes vertical shot stringing. Happens with weak firing pin springs, too.

Messing with lock time; yes, but here's an example of how much. If a firing pin's fall to a primer seated .002" below the case head is .0025 seconds, a primer seated .002" above the case head, lock time wil be about .00246 seconds; 1.6% faster as the primer's .004" closer (assuming it's not been seated fully by firing pin impact). As lock times (in the best of mechanical systems) have a 3 to 4 percent spread, that's insignificant. Ignition time may vary; that's the time between the primer's cup starting to dent in smashing the anvil and crushing the priming pellet detonating (fast burning) it.

 

[ehryk]

Ignition uniformity; yes, sometimes a whole bunch; causes vertical shot stringing. Happens with weak firing pin springs, too.

Messing with lock time; yes, but here's an example of how much. If a firing pin's fall to a primer seated .002" below the case head is .0025 seconds, a primer seated .002" above the case head, lock time wil be about .00246 seconds; 1.6% faster as the primer's .004" closer (assuming it's not been seated fully by firing pin impact). As lock times (in the best of mechanical systems) have a 3 to 4 percent spread, that's insignificant. Ignition time may vary; that's the time between the primer's cup starting to dent in smashing the anvil and crushing the priming pellet detonating (fast burning) it.

What he is saying in short is only the top bench rest shooters may see the difference. I am NOT one of those, most of here arent either lol

 

[Bart B]

What he is saying in short is only the top bench rest shooters may see the difference. I am NOT one of those, most of here arent either lol

Bench rest shooters are not in the only competitive discipline where top accuracy is important even though they shoot their rifles in virtual total free recoil untouched by humans. There's others who fire rifles off their shoulders in three or four positions at the top of their rankings who can also tell the difference; their rifles and ammo's just as accurate as what the bench rest folks get.

 

[jasonoldman]

Thanks for the reply's guys, Yes this particular batch is win brass. I also have federal and nosler brass on hand have you seen as much problem with those. Plus I have had some bit of vertical stringing so I like that it may be tied into this other problem.

Do you just use a pocket uni-former on the cases

 

[Mikecr]

Don't ever think that primer striking is insignificant.
Variance in it, and/or bad striker setting for a given primer, or bad bolt timing, can definitely affect performance(flyers,, worse grouping).

It appears to me that most BR shooters rarely consider it, as it also appears that most rarely represent actual competition. Keep this in mind when considering all the little things, that your cartridge can't work around -like a tiny 6PPC @ 75Kpsi can.
When you wanna really dial in something like a 243Win @ 55Kpsi, you need to pay attention to possibilities in bullet & primer seating. They matter for you.

 

[Bart B]

Do you just use a pocket uni-former on the cases?

No, nor any other case prep except trimming to some minimum length and turning case necks if they've got more than a .001" spread in wall thickness. Even tried uniforming flash hole diameters as well as tapering the flash hole from the inside getting rid of the burrs there. None of it made any difference.

 

[Lefty7mmstw]

Ignition uniformity; yes, sometimes a whole bunch; causes vertical shot stringing. Happens with weak firing pin springs, too.

Messing with lock time; yes, but here's an example of how much. If a firing pin's fall to a primer seated .002" below the case head is .0025 seconds, a primer seated .002" above the case head, lock time wil be about .00246 seconds; 1.6% faster as the primer's .004" closer (assuming it's not been seated fully by firing pin impact). As lock times (in the best of mechanical systems) have a 3 to 4 percent spread, that's insignificant. Ignition time may vary; that's the time between the primer's cup starting to dent in smashing the anvil and crushing the priming pellet detonating (fast burning) it.

Yes bart, in a bolt gun a 1/2 second bullet travel time will only change a little over an inch where the bullet impacts on a deer at full run with a .00246 second variance in lock time. It is variance nonetheless. Your example is in a relatively quick locktime bolt gun; other actions are sometimes a bit slower and would show more variance.

 

[Bart B]

Yes bart, in a bolt gun a 1/2 second bullet travel time will only change a little over an inch where the bullet impacts on a deer at full run with a .00246 second variance in lock time. It is variance nonetheless. Your example is in a relatively quick locktime bolt gun; other actions are sometimes a bit slower and would show more variance.

Check your math.

 

[Lefty7mmstw]

Check your math.

45 fps( a 30 mph run)
* .00246 second variance(your number)
= .1107 ft
* .5 second
= .056 foot
*12
=.672 inches

Checked--double checked-- about 2/3 inch-- I mis-spoke and said just over an inch
rounding to coarsly earlier had me up a bit
take a 1903A3 at around .0065 second lock time and you'll be well over in inch-- the .00246 second quoted seems to be for a rem short action from a quick google, the long action m700 is more like .003 second.