ok I have a sako trg in 338 lapua, been working on loads using foster br sizing and seating dies, i had no reason to think there might be a problem (other than having some strings open up to .75" from .4 almost all the time!) until i tried loading barns x bullets, i found they would come out by hand after seated, i measured everything, barnes x bullets were .337, lapua bullets were .338, the dies were sizing the brass necks to .337, im sure thats fine for singleshot br rifles but what about what im using? could they be shifing in the cases when firing, ( i do have a brake on the rifle and it feels more like a 308 than a 338) and would that change in seating depth give me different points of impact when shooting 5 shot strings maybe?
is this potentialy a cause for wandering bullets on paper?
m

The bullets should be held tight enough, by case neck tension, that they not move in the case due to recoil (much less by hand). The change in OAL will result in the change in accuracy. More importantly, the change in OAL will also change the chamber pressure, and may cause it to rise to unsafe levels.

I would suspect from your description that the expander button on the decapping pin (in the sizer die) is too large in diameter. Remove it, size a couple pieces of brass without it. Seat the bullets in this brass and see if that does not give you adequate neck tension.

If that fixes the problem, get with Forster and they will get your die functioning to standard. Even if it does not fix the problem, give Forster a call. They are pretty responsive to quality control problems and good at sorting out problems that might occur with any of their products.

do u get a loose bullet pull with all makes of brass? could be just one lot of brass causing the problem

One of the most critical measurements for consistency is neck tension.

Barnes X (in particular older samples of the orginal X) were notorious for consistency problems. I'm not too surprised by the bullet diameter being .337" as opposed to the expected and advertized .338". Newer Barnes products - in particular the TSX bullets - have become a lot better.

If you contact Barnes, I'm pretty sure they'll help you out with your undersized bullets, they did for me some years back with some monolithic solids.

quote:

Originally posted by AZ Pete:
I would suspect from your description that the expander button on the decapping pin (in the sizer die) is too large in diameter. Remove it, size a couple pieces of brass without it. Seat the bullets in this brass and see if that does not give you adequate neck tension.

I suspect AZ Pete is right - since your dies seem to size your brass sufficiently for .338" bullets, and since the expander is what controls neck tension in your particular die.

You can certainly take Pete's advice of trying to seat a couple of bullets in brass sized without an expander. Most likely, you'll have quite a bit of trouble seating those bullets, though.

A regular sizing die (your Forster FL die is an example) works by initially sizing down the neck a whole bunch, and then pull the expander through to open the neck to the diameter required. This is a pretty brutal way of sizing brass, and the process is (in)famous for introducing runout. But doing it this way has the advantage of always working, even with workhardened brass. Die manufacturers need processes which always work, worries about runout is for the odd handloading aficionado.

So sizing without your expander is likely to produce necks sized down so far (in anticipation od subsequent expansion), that you'll have a hard time seating your bullets. In fact, the bullet will need to do the job the expander normally does, and that is asking for the bullet to be damaged at the heel - about the worst place you can damage a bullet.

OK, Pete's suggestion was not intended for you to load your rounds like this from now on. And he is probably right that your expander is dimensioned for .338" as opposed to .337" bullets. If you insist on working with the .337" bullets, you had better measure and possibly polish down your expander about .001 - .002", no more than that should be necessary if you normally don't have trouble with .338" bullets. The easiest way would seem to be to get bullets that meet specs, though.

- mike

PS: Hard to say why you are not getting the groups you'd like. Even with a brake, the .338 Lapua is not exactly a BR rifle, and many (make that most) people would be content with .75" groups.

ok sounds good, I dont plan on using the x bullets, i had them and wanted to try them, and it brought me to this discovery, was wondering if it was affecting my accuracy at all with the other bullets, as for group size of .75 being good enough for .338, it is in a sako TRG and i get anywhere from .4-.75 depending on how warm the barrel is, maybe if thats the range i should expect ill live with the current loads and work on my own shooting ablities, this is not for BR shooting its for sniper matches, so i want to make sure my ammo is going to be as good as it can get then work on my own shooting,

You may want to consider a Lee Factory Crimp Die. It will give you more consistant tension on the bullets.

Reloader

Even with a good crimp, if there is no neck tension, the bullet will not be adequately held. You will be able to spin it with your fingers, even though it is held in the case with the crimp. I have experienced this with an oversized expander button in .308 dies, and also when crimping .452 bullets with a set of dies for .454 (Long Colt). IMHO you have to have good, consistent neck tension for accuracy and weather tight loads.

This to me sounds like an expander ball problem regardless of the Barnes bullet dimension. .001" of a change in bullet diameter shouldn't be enough to cause such a loose seating condition. I bet all your bullets are a little too loose. I would want at minimum .002-.003 for neck tension for a big cartridge like the .338 Lapua especially given that you want to use the rifle as a repeater. Soft seating (minimal neck tenssion) CAN work, but normally this technique is used in situations where you are single loading and when the bullet is normally seated .010" into the lands to create a jam situation.

I would mic the expander ball for a reference number and then emory the ball down, while spinning it in a drill chuck, at least .002".

Gabe