never had this before

[Oh Mah]

For the first time with new brass i had to chase down a major problem.A heads up for reloaders.I have been reading some threads on here about case volume problems lately and have come to another problem because of it.I have been loading 81grains of H100 powder in my .300 win mag for over a year now,It is a very good load.Tack driver if you will.3100 fps.Now all of a sudden im chasing c.o.a.l all over the place and when checking with the gauge im .025-.035 long on datum line.


 The max load now all of a sudden is swelling the case at the datum making it to long to chamber.

Now i will have to extend the c.o.a.l out closer to the lands hoping to keep accuracy and speed so i dont have to order a new dial for my scope.

What have i learned from this?DON'T PUSH THE LIMITS OF YOUR CASE CAPACITY LOL.YOU MIGHT HAVE TO START OVER. 

[b23]

What bullet is this 81gr of H1000 with???

[Oh Mah]

.300 win mag nosler 180 b/t

[b23]

Depending on your OAL, 81gr of H1000 with that bullet is a very compressed load and it's very possible the actual powder itself is what is messing with your OAL.  Are you using a drop tube?  If not and you plan on staying with that particular load a drop tube could help.

Have you tried any H4831sc or RL26?  RL26 will probably gain you 75-100fps over your current load and it'll be right around that 98-99% fill capacity instead of the 110% you're at now.  Maybe worth trying.

[Oh Mah]

Thanks but i took all of the problem loads apart,Resized them all again and measured my chamber.I moved the Coal out to half way between.3.450 instead of 3.340.Chamber measured 3.520.This will give the load more room and wont cause the bullet to compress the powder.All of what you said is what i came to also.The brass volume is to small for the max load with the coal set at recommended lengths.  This is all do to needing to buy new brass as the brass i was using has been used enough lol.

[Hilltop123]

Just out of curiosity, what make is the offending brass?

[Oh Mah]

P P U.  MADE IN SERBIA.
I know i know,But its all they had at the time   

[Hilltop123]

Had issues with PPU, myself. Needless to say, it got round filed.

[BrandonWatts]

How many rounds down the barrel? My guess if your coal is having to be lengthened you are starting to see some throat erosion in you barrel. Have the barrel looked at with a borscope. Just a guess.

[Oh Mah]

no no and no.the problem is case volume,double checked with fluid measure.the max charge for this load is a compressed load.with the lower volume the compressed load is swelling the shoulder enough to where it wont chamber.fails the go no go gauge.I spoke to a loader of many decades and he has advised me to never measure c.o.a.l again,only measure ogive because bullet tips could be all over the place.i have moved the ogive out .150 he said it will slow down some maybe 100 fps but should not change accuracy at all.but will throw the dial off a little the farther out i shoot. 

[b23]

no no and no.the problem is case volume,double checked with fluid measure.the max charge for this load is a compressed load.with the lower volume the compressed load is swelling the shoulder enough to where it wont chamber.fails the go no go gauge.I spoke to a loader of many decades and he has advised me to never measure c.o.a.l again,only measure ogive because bullet tips could be all over the place.i have moved the ogive out .150 he said it will slow down some maybe 100 fps but should not change accuracy at all.but will throw the dial off a little the farther out i shoot. 

I'm not trying to be a Richard Noggin here so don't take these comments as such but there is sooo much wrong with the information you were given that it's scary.

As I said in my earlier post a few days ago, you have a very compressed load and when you seat the bullet the powder column will only compress so far before it starts pushing the bullet back out of the case and that is what is causing your inconsistent OAL readings.

If you have loaded rounds that won't chamber after you seat a bullet, it's highly unlikely you're "swelling the shoulder" with your compressed load but rather it's likely you are slightly deforming/crushing the case when you are seating the bullet because of the extra force needed to seat the bullet due to the fact it's such a compressed load.  This is assuming you are FL sizing them enough to fit back in the chamber after they are shot.

Yes, measuring off the ogive will generally give you a more consistent OAL but we are only talking about a couple thou which is kind of contradictory to what your friend told you because according to him you can change you seating depth 150 thou and it "should not change accuracy at all" which, again no disrespect intended, is just laughable to say the least.  Changing seating depth by 150 thou is a HUGE change.

As for lowering the velocity by seating the bullet out another 150 thou, this is a yes or no kind of thing and will depend on how close you are to touching the lands.  I don't know how close you are to touching the lands but as you start getting close to the lands the pressure goes up and will increase velocity.

[baker5150]

no no and no.the problem is case volume,double checked with fluid measure.the max charge for this load is a compressed load.with the lower volume the compressed load is swelling the shoulder enough to where it wont chamber.fails the go no go gauge.I spoke to a loader of many decades and he has advised me to never measure c.o.a.l again,only measure ogive because bullet tips could be all over the place.i have moved the ogive out .150 he said it will slow down some maybe 100 fps but should not change accuracy at all.but will throw the dial off a little the farther out i shoot. 

I'm not trying to be a Richard Noggin here so don't take these comments as such but there is sooo much wrong with the information you were given that it's scary.

As I said in my earlier post a few days ago, you have a very compressed load and when you seat the bullet the powder column will only compress so far before it starts pushing the bullet back out of the case and that is what is causing your inconsistent OAL readings.

If you have loaded rounds that won't chamber after you seat a bullet, it's highly unlikely you're "swelling the shoulder" with your compressed load but rather it's likely you are slightly deforming/crushing the case when you are seating the bullet because of the extra force needed to seat the bullet due to the fact it's such a compressed load.  This is assuming you are FL sizing them enough to fit back in the chamber after they are shot.

Yes, measuring off the ogive will generally give you a more consistent OAL but we are only talking about a couple thou which is kind of contradictory to what your friend told you because according to him you can change you seating depth 150 thou and it "should not change accuracy at all" which, again no disrespect intended, is just laughable to say the least.  Changing seating depth by 150 thou is a HUGE change.

As for lowering the velocity by seating the bullet out another 150 thou, this is a yes or no kind of thing and will depend on how close you are to touching the lands.  I don't know how close you are to touching the lands but as you start getting close to the lands the pressure goes up and will increase velocity.

 
I had the same issue as the OP and I'm fairly certain this is what is happening, I haven't had time to measure them out yet.

[Oh Mah]

first i appreciate the ideas keep them coming.second no hes right you can have a crushed tip on bullet throwing over all length out the window.I've had deformed b/t tips as well that would account for easily .025 o.a,l. . Third i loaded this round for over a year in lapua brass no issues.I know it is a compressed load 102%.inside this new cheap very soft brass holds less fluid period.It is compressing the 102 %load and swelling the shoulder.All measurements have been taken between each step and it is swollen after bullet is seated.not crushed swollen.  thanks.

[Oh Mah]

This thread was an attempt to give a heads up to fellow reloaders,Not a question of why something is happening.I already know whats going on and thats why i made this thread.

[b23]

So you're concerned about .025 variance in OAL changing accuracy but you don't believe changing your seating depth by .150 will "not change accuracy at all"