Stiff extraction issue

[Alistair]

So here's the situation.

I've got a Tikka M695 in .270Win which has recently been rebarrelled with a Bergara barrel. The rifle shoots various types of factory ammo fine (federal, remington, ppu, hornady, sako) and groups pretty well, so now I have some fired cases I've been working up a load.

The first step was to sort a pressure series using book values for N160 and a generic 130gr softpoint. But here's the issue. Every round I've tried, from 53.5gr to 56.5 or so, exhibits stiff extraction.

All the cases I'm using are 1x fired PPU, fired in my rifle, which were originally neck sized and checked for length - all are less than the maximum book value.

Having had this issue first time around, I pulled all the rounds and full length resized instead. No dice.

Velocities are pretty low, at around 2800 for the 54.5gr loads, and no other pressure signs are visible.

Primers are Federal Gold Medal (Large Rifle) and OAL is 3.228". The loads do have a mild crimp, to ensure decent function in a magazine, but this is by no means excessive.

I've had the suggestion that the pressures are in fact too low, and the cases aren't adequately gripping the chamber, leading to increased bolt thrust, but experimentation with a few rounds towards the upper end of the book range doesn't seem to support this.

The chamber seems fine, with no obvious imperfections.

Does anyone have any experience of stiff extraction on low end loads? Any ideas would be very welcome. What am I doing with the homeloads that the factory isn't?

Cheers,
Al.

 

[Techcoat]

Try different brass ppu can be a bit off in some guns

 

[Alistair]

Thanks for that. That was my thought as well. It's a bit odd that these PPU cases have already fired and extracted once in this rifle with no issues with the original factory loading, but they are causing issues the second time as homeloads though?

 

[ChesterP]

Try FL resizing them.

The loads don't sound especially hot but my experience with PPU is that FL sizing is a must in my .308.

 

[Miki]

I see that you said even after full length resizing you were still having issue. It could be that the headspace is wrong as your die is to far out/away from the holder. Try screwing it in so you need to put some pressure behind the bar to get over center (without a case in the press).

 

[Muir]

Check to see that the rim fits freely on the bolt face and under the extractor.~Muir

 

[Alistair]

Case rim seems to fit fine on the bolt face. Fits fine under the extractor as well. Headspace could be a consideration, they are new (to me) dies and haven't been used previously with that rifle. THat said, the cases seem to chamber fine before firing, and if I reinsert a fired case into the chamber it will again, get stuck.

The initial 'rotation' of the bolt takes no additional effort either, just the rearwards stroke.

 

[Yorric]

It sounds like the cases are tight along the sidewalls jamming against the chamber. Maybe the brass is not elastic enough on the lower sidewall & has deformed without normal spring back. Or it may be a die diameter issue, or a die setting issue, combined with a chamber diameter issue or chamber surface finish texture.
Try different new or factory brass from a different maker, shoot it, reload it & see what happens.

Ian

 

[Alistair]

It sounds like the cases are tight along the sidewalls jamming against the chamber. Maybe the brass is not elastic enough on the lower sidewall & has deformed without normal spring back. Or it may be a die diameter issue, or a die setting issue, combined with a chamber diameter issue or chamber surface finish texture.
Try different new or factory brass from a different maker, shoot it, reload it & see what happens.

Ian

A good point. I marked up a fired case with a marker and chambered it to try and see where it is binding. Does look like there is some light contact/ rubbing on the case wall just above where the web is internally, as well as at the point where the shoulder changes to the parallel sides of the main body.

Dodgy brass deforming upon a second firing and not 'rebounding' may be an answer.

I'll see if I can get some of the Sako or Federal stuff FL sized and loaded up this week to the same series and have another crack next weekend.

In the mean time, more thoughts or wisdom are most welcome.
Al.
A

 

[Border]

How have you set up your FL die?

 

[Yorric]

Alistair be sure that you have set your bullet seating die up right & are not bumping the shoulder to body transition & swelling it on diameter. If you are using a Lee Factory Crimp Die, do not let the seating die do any crimping at all.(back the seating die body out of the press as per Lee instructions).

Ian

 

[VSS]

Maybe "stiff extraction" should be in the double meanings thread? I can think of at least four ways to interpret that.

 

[Ronin]

few questions and thoughts:

Are you using new brass or fireformed brass from the OLD barrel in the NEW barrels chamber?

If the former, you should not experience hard extraction.

If the latter, the witness mark near the case web is indicative of brass that requires FL re size (however I would source NEW brass rather than use old brass from another chamber in a rebarrelled rifle)

Have you tried putting some factory ammo through the rifle - suggest you do and advise if you still experience extraction issues

Lastly, you say there are no signs of poor finish on the chamber (no radial lines or pitting on the extracted brass) so its unlikley to be the chamber.

If the rifle has been recently rebarrelled and its been through Proof, then its likley not to be "poor headspace" its also likely nothing to do with increased bolt thrust because the chamber is polished - utter bxxllxxs, the bolt is designed to take the load from the firing cycle, not the case gripping the chamber....

Be interested to hear how you go on with this

 

[petesv]

A friend of mine had same problem with an x bolt he stopped crimping problem stopped , i was told not to crimp in a bolt action rifle , try no crimp .
keep us informed Pete .

 

[Alistair]

The die is set up as per the Lee instructions. Basically, put the ram up, screw the die down until it makes contact, lower the ram, 1/4 turn more, tighten lock ring. As per someone elses suggestion, this leads to a bit of pressure being required to bring the ram over the 'top' with no case inserted.

Brass used was 1x fired in this rifle and this barrel. Factory rounds of various types fire fine and exhibit no issues.

I'm going to try some federal 1x fired (in this rifle) next and see how I go with that. This is FL resized as before, trimmed to book min value and will have a slight crimp.

If there are still issues, I'll try no crimp and maybe some new brass.

I'll lt you know how it goes at the weekend.

Cheers!
Al.

 

[Whitebeard]

Expansion of the web in front of the extractor groove is often a cause of hard extraction and chambering, FL sizing does not usually fix this, mark the case all the way round with a sharpie about half an inch up from the base, chamber it and extract it then look for scuff marks in the ink.

Ian.

 

[JTO]

Alistair be sure that you have set your bullet seating die up right & are not bumping the shoulder to body transition & swelling it on diameter. Ian

= My first thought.

 

[JTO]

The die is set up as per the Lee instructions. Basically, put the ram up, screw the die down until it makes contact, lower the ram, 1/4 turn more, tighten lock ring

I was getting a doughnut at the body-to-shoulder junction when I did this.
Measure the case at this point before and after seating the bullet.

 

[shendy]

Have you tried a fired round before you reload in and a loaded round with out firing?

 

[ejg]

My guess is chamber with too small diameter in the web area. In a 308 or 223 a small base die would fix it, not sure if they are available in a 270.
We had once 4 barrels/rifles chambered with the same (apparently new) reamer, all were too small or very tight in the web area. Some factory ammo was even tight when closing. Mostly tight when opening. Wasn't the head spacing in our case.
edi