6.5x47 Lapua not chambering

So was shooting 800, 900 and 1000yrs at Clevdon on Saturday and had trouble with some rounds not chambering. They are 3-4 times reloaded luckily I had some loaded up with new brass so was able to finish the day off ok. When I got home I checked the shoulder which I only bump 0.003 from fired and this wasn't the problem. I found that the problem rounds have a measurement of 0.47035-45 at the base where as the new brass unfired was only 0.46925-35. That same new brass when fired and resized measured 0.46995 So it seems the base of the case is slowly increasing in diameter even though I have tried screwing the die to make hard contact with the shell holder and running them through. This is not something I have ever run into before.

Yeah I know you are going to say over pressure loads but with a Lapua brass and Lapua 123gr Scenars 37.7gr ADI2208 at 2883fps and no loosening of the pockets I can't see that as the issue. I had thought of trying a body die even if I have to grind off its base to give the brass more of a squeeze. This will of course bump the shoulder way more than required but I could machine the shoulder portion out of the die as well to stop that problem. Any ideas anyone. Maybe some brands of die have smaller dimensions than others am using Redding dies.
Thanks

You need the Redding small base dies by the sounds of it.

Where are you measuring at the base? Brass is usually tapered a bit at the bottom and not worked by the die at all.

Check that the neck hasnt gotten thicker.

It is called case head expansion and excessive case head expansion is a sign of over-pressure.
I assume you are using the Lapua 6.5x47L small primer pocket cases and they handle excessive pressure better with regards to loose primer pockets.

I am not familiar with 2208 in the 6.5x47 so can't really comment on your loads other than to say the velocity doesn't look particularly high (well... depending on your barrel length).

I would expect that if you go to small base dies (more used in semi-autos) or go to excessive shoulder bump to attempt to resize the base of the case you will over work the rest of the case and without annealing you will likely reduce the life of your cases through work hardening and cracking.

As you suspected if you are not happy with 4 reloads per case (and I wouldn't be...) then I suggest you change your load.

Just a side track - What sort of micrometerare you using ?
mine measures 3 digits then the last one is .xxx5 or .xxx0.
So yours measures better than 1/10000 inch ?
It sounds as if your bases are now about.001" (a thou) bigger than when new.

Could your necks be stretching ? I have to trim between .005 and .010" off the end of my cases after 3 or 4 reloads. For some resson it varies aclot from case to case.

For the case head to have expanded to give a tight chamber fit I think the primer pocket would not be usable.
Your load also seems right for around 60kPSI peak in a 25-26" barrel.

A thick or long neck causing a jam on chambering can usually be seen as marks on the brass once extracted unfired. Maybe blacken the neck with a pen to check so this can be eliminated from the options?
Did you fire any of the problem rounds? The jump in pressure from a significant neck jam would surely be visible on the primer.

It sounds to me that the sizing is just not quite enough somewhere between the expansion line on the case wall above the head up through to the shoulder-neck junction.
I've not personally had a die-chamber dimension mismatch that has meant that the walls were not sized in enough. On the other hand I have had to grind the bottom off dies to have them push the shoulders back far enough, so my pick would be the shoulder needs to come back more. I have also found that shoulders move more than expected on 6.5x47 Lapua brass with moderate pressures. I now use a Redding body die on every case every reload and then cycle a few (empty) to check clearances.

I run mine at 38 grs with the same components and have had no base expansion even after 5-6 loads.

Does sound though as if your problem is base expansion. DON'T shag with the dies, just buy a body die.

Thanks guys for your thoughts. I have asked the same question of Redding as I am using their dies but have had no response yet.

I can say without a doubt that it is not the shoulder that is causing the problem as I have one of Larry's digital headspace gauges Innovative Technologies - Reloading Equipment and I have checked the measurements
Case trim length is 1.843 so that's so the issue either.
There are no rub marks on the neck so I am pretty sure that neck thickness is not causing the tight fit I am reasonably confident its the base of the case expanding. If this is caused by excessive pressure I am not sure. This load is used by other shooters in the US all be it Varget not 2208 and I am coating the bullets with the Tubb Boron Nitride which will reduce pressure. I will go back to the range and try some reduced loads I still have all the chrony info from when I worked up the load. @dogmatix the small base die is not made in 6.5x47L @Bagheera its an old Mitutoyo digital @6x47 thanks for your load info I will see what Redding says

Take a fired piece of brass. Measure the shoulder with something like a hornady headspace gauge.

Size it as you would do normally. Measure the shoulder again to confirm you have bumped it back a couple of thou.

Try to chamber that piece of brass. If the bolt is hard to close, the likely problem is the base. Use a Redding SMALL BASE body die. This is different from the normal body die.

Yep, as ebf says, the Redding small base body die.
Given the 6.5x47L dimensions, use the .260 Rem, it will only work the body diameter, it will not touch the shoulder.

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Originally Posted by Dermastor

Thanks guys for your thoughts. I have asked the same question of Redding as I am using their dies but have had no response yet.

I can say without a doubt that it is not the shoulder that is causing the problem as I have one of Larry's digital headspace gauges Innovative Technologies - Reloading Equipment and I have checked the measurements
Case trim length is 1.843 so that's so the issue either.
There are no rub marks on the neck so I am pretty sure that neck thickness is not causing the tight fit I am reasonably confident its the base of the case expanding. If this is caused by excessive pressure I am not sure. This load is used by other shooters in the US all be it Varget not 2208 and I am coating the bullets with the Tubb Boron Nitride which will reduce pressure. I will go back to the range and try some reduced loads I still have all the chrony info from when I worked up the load. @dogmatix the small base die is not made in 6.5x47L @Bagheera its an old Mitutoyo digital @6x47 thanks for your load info I will see what Redding says

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Your chamber is probably a little smaller in diameter at the base than the dies you have.

As previously mentioned you will need to get a body or FL die that is smaller than the one you have ie a small base die

It probably has little to do with your load if the brass isn't showing obvious signs of over pressure.

It takes very little in diameter to up set things.

As soon as you go to the expense of custom dies you realise most dies size way too much

Thanks for confirming that the shoulder is not an issue.
If it is of any help the dimensions on fired brass here ( at 60-65kPSI peak) are also 0.4705" at the expansion line - the point of maximum diameter about 6mm above the head. The Redding body die here - and I believe it is the standard die 75479, not small base - takes the walls in so that they again taper down uniformly from immediately above the extraction groove at 0.4697" to the shoulder.
I can't positively say that this body die would reduce your 0.46995" dimension because I don't know where you took your measurements when you referred to the "base" - how far above the upper edge of the expansion groove - but it sounds like your die is not taking in the walls as much as the die here would. You said in your OP you had thought of using a body die, so if this means you are using the sizing die from a Redding 2-piece set then maybe see if you can borrow a regular Redding body die to try out before looking at the other options?

I checked the shoulder which I only bump 0.003 from fired and this wasn't the problem. I found that the problem rounds have a measurement of 0.47035-45 at the base where as the new brass unfired was only 0.46925-35. That same new brass when fired and resized measured 0.46995 So it seems the base of the case is slowly increasing in diameter even though I have tried screwing the die to make hard contact with the shell holder and running them through. This is not something I have ever run into before.

I have a Redding .308 small base die measuring the brass i just resized it is .4663" so that would solve your problem, Ask the Clevedon guys I am sure one of them will have a small base .308 die I have used my .308 die to size 6mmBR .243 and 7mm08 the only problem you may have is the diameter of the shoulder on the 6.5x47 it could be to big to fit without being sized down.

You guys are blood intelligent buggers. I am using a full length Type s bushing die and that's not doing it. The barrel chamber is probably tightish as its a replacement barrel (the rifle was a 22-250) Ok I hear what you are saying before I start mucking up my accurate load I will try a small base 308 die. I checked the 6.5x47 brass against a 243 brass I have and at the shoulder the 6.5 is slightly smaller than the same part of the 243 case so that will work. I happen to be in Hawaii in a few weeks so I will include a small base body die in the order I have with Sinclairs. Any of you guys that have made helpful comments need anything (small) from Sinclairs? I am back mid Feb.
Thanks

One more thing to think about . . . . my target chamber "tight but no turn" neck 223 is very intolerant of un chamfered brass. If I don't use a tool on the case mouths after a trim or even just let them get crappy they won't chamber.

So check at what stage of the chambering process are they jambing ??

Who chambered the barrel? Ive seen a similar problem with a 280AI, where the reamer used was worn and cut an undersized chamber, creating the same issue you have.

It was fixed by having the chamber recut by another smith with a reamer that wasnt worn out.

Thanks guys for your comments I wont go into who did what without being able to measure the chamber. @Tentman the brass is ok no burs

Well back from Hawaii armed with a small base body die (.308). I have run the offending rounds through it and no difference. Grrrrrrr. Even run through it they still measure at worst.46995 at the largest measurement of the case. The point of go no go is .46935 so there is very little in it. Puffin you mentioned that your sized brass is .4705 that would never fit in my chamber. The base diameter in drawings of the case is .470 so if anything bigger than .46935 wont fit I can probably assume the chamber is more than a little tight. I will approach the Smith who chambered the rifle and have a wee chat

Im impressed you can neasure to 1/100,000 of an inch or am i misreading this?