Pressure Issues

KYyeeter

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I have a factory Remington 700 action with a criterion remage barrel. When I put this rifle together my only goal was shooting distance for fun. Since then I have dove head first into prs and hopefully will be upgrading my action and barrel soon. However until then this is what I have to work with. My problem or question, I recently shot during rain and humid weather and the bolt was very hard to close and open. Shooting factory hornady 6cm 108 eldm, I was told that more than likely it was not the ammo and was probably a pressure issue. Possibly headspace too tight? Also marks on the bullet like it’s getting shoved too far into the lands. When I assembled this I had it to where the bolt would almost close on a no go gauge but not fully lock down. Is this something I can fix by backing the barrel off a couple thou or what are some recommendations or other thoughts on the problem? Also had the same problem out of 6.5cm remage barrel but only in rainy conditions. Help a clueless guy out.
 

KYyeeter

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Thanks for the help. I’ll give the chamber a good cleaning and recheck headspace.
 

mi223

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Sounds like headspace is fine. Is it a newer barrel? Sounds like it may have a short throat and you are jamming the bullet into the rifling.

I would sharpie (layout dye is even better) a bullet and chamber in then extract loaded round and look for marks that look like rifling.

If that is it then you have some options but none of them are ideal
 
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KYyeeter

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Sounds like headspace is fine. Is it a newer barrel? Sounds like it may have a short throat and you are jamming the bullet into the rifling.

I would sharpie (layout dye is even better) a bullet and chamber in then extract loaded round and look for marks that look like rifling.

If that is it then you have some options but none of them are ideal
Yes it is a new barrel. Maybe 200 down it. If I eject a live round, I can see marks on the bullet almost down to where it seats in the brass.
 

KYyeeter

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IT sounds like the throat is too short, and bullets are jammed into the lands. This will spike pressure also. Did you change ammo or bullet?
Factory hornady 108 eldm is the only thing I’ve ran. Doesn’t mean there wasn’t a difference between boxes I guess. I’ll have to mic them and see. But again I only had this problem in bad weather. Got to the house and dried things out and everything cycled fine. Fine for factory r700 standards that is, not smooth as glass by no means.
 

Supersubes

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    I think it has less to do with taking up space in the chamber and spiking pressure, and is more likely that its floating/lubricating the brass against the chamber. So internal pressure is the same or nearly so, but bolt thrust loads are high. You can test this with a chrono.


    @KYyeeter can you take a pic of the marks on the bullet? Its not unusual to have one side of the bullet scrub against the freebore. In a typical match chamber there’s only .0005 clearance total ( .00025 per side). Even a slight lack of concentricity with the cartridge will cause contact.
     
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    KYyeeter

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    I think it has less to do with taking up space in the chamber and spiking pressure, and is more likely that its floating/lubricating the brass against the chamber. So internal pressure is the same or nearly so, but bolt thrust loads are high. You can test this with a chrono.


    @KYyeeter can you take a pic of the marks on the bullet? Its not unusual to have one side of the bullet scrub against the freebore. In a typical match chamber there’s only .0005 clearance total ( .00025 per side). Even a slight lack of concentricity with the cartridge will cause contact.
    I will this evening. Thanks
     

    CK1.0

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    As far as .243/6mm bullets go, 108 ELD-M's are actually pretty long, they like .183 freebore or longer and many chambers (maybe yours) come shorter than that (for example, a .140" freebore is popular for guys who want to get 105's right up on the lands, and I've heard of an even shorter .109" offered as a 6CM freebore option), also, IIRC the factory loaded ammo comes out of the box at nearly max magazine length.

    If you have access to a reloading rig, you could seat the bullets a few thou deeper (so they're not getting jammed into the lands), and I bet all that pressure stuff will go away.

    If water in the chamber was half as big of a deal as some make it out to be, half of the rifles at the last GAP Grind would've blown up (it was fucking pouring), and AFAIK nobody's did.
     
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    hafejd30

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    I’m just guessing it’s a carbon ring (maybe not correct term) coupled with the added moisture that is causing this

    Clean the gun. Bore tech C4 or something of the sort for the carbon. Then retest
     

    KYyeeter

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    EE948A47-5D43-4A21-BAF5-707BFDAB9EE0.jpeg
     

    KYyeeter

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    There's your answer. Doh.
    What’s that mean? Seriously, I don’t know what I’m looking at. I’m still pretty green when it comes to bolt actions.
     

    Supersubes

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    What’s that mean? Seriously, I don’t know what I’m looking at. I’m still pretty green when it comes to bolt actions.
    Pictures are blurry, but it looks to me like you have a tight freebore. Thats not lands engraving. Clean the shit out of it, paying special attention to the throat. If that doesnt work, send the barrel back.
     

    CK1.0

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    What’s that mean? Seriously, I don’t know what I’m looking at. I’m still pretty green when it comes to bolt actions.

    I was typing... hahaha.

    What I added above and...

    You're going to need to seat those bullets deeper, looks like you have a short throat/freebore, and 108ELD-M's are long, so the bullet is getting jammed into the lands.

    (...and it looks like by kind of a lot, so yep, that'll yield pressure issues...)

    First though, since it's a Remage setup, verify that your headspace is set correctly, and redo it if you need to.

    If the headspace is fine, you're going to have to seat those bullets deeper.... if I had to guess I'd say maybe as much as .020" or more (this is why I recommended finding out where your lands actually are with the Deep Creek method).
     
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    CK1.0

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    Pictures are blurry, but it looks to me like you have a tight freebore. Thats not lands engraving. Clean the shit out of it, paying special attention to the throat. If that doesnt work, send the barrel back.

    Judging by all that marker all over the place, I think he needs to get a better idea about what's going on before he goes blaming the barrel... but those pics do make that freebore indeed look damn short, so I wouldn't rule out the barrel being fucked up either.

    OP, get another round that's never been chambered, and try to only color in the bullet, nice and evenly and pretty... then try to cleanly chamber it just once, and extract it cleanly, just once. Then examine it closely for where it's jamming.

    P.S that looks like it's jamming enough to where you might rip a bullet out on extraction and get powder all over the place, so don't go at it in your living room, be aware that can happen if the bullet gets stuck.
     
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    Supersubes

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    Judging by all that marker all over the place, I think he needs to get a better idea about what's going on before he goes blaming the barrel... but those pics do make that freebore indeed look damn short, so I wouldn't rule out the barrel being fucked up either.

    OP, get another round that's never been chambered, and try to only color in the bullet, nice and evenly and pretty... then try to cleanly chamber it just once, and extract it cleanly, just once. Then examine it closely for where it's jamming.

    P.S that looks like it's jamming enough to where you might rip a bullet out on extraction and get powder all over the place, so don't go at it in your living room, be aware that can happen if the bullet gets stuck.
    Its rubbing the freebore mostly. Hard to tell from the pics, but it doesn't look like its engraving.
     
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    CK1.0

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    Its rubbing the freebore mostly. Hard to tell from the pics, but it doesn't look like its engraving.

    ...could be, those pics make it hard to tell what exactly is going on there. It's definitely hitting something...
     
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    KYyeeter

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    Yea it was hard to get a decent pic. I’ll post an update after I try y’all’s suggestions. Preciate the help.
     

    KYyeeter

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    Update: I cleaned the chamber really good. It was pretty nasty. No issues since but I haven’t had a chance to try in the same conditions as before. Also sold it and bought an impact barreled action 😁 thanks for your help!