M852 .308 chamber reamer??



  • Can anyone direct me to a chamber print of the M852 chamber reamer. I see it talked about all over the place but can't find a print. The general concenses is that it a little tighter tolerance than the SAAMI .308 in the neck with a slightly shorter freebore. Supposedly it is the original "match" chamber design for the 168 SMK projectiles.

    Any input on where or not this is a desirable chamber for a general purpose .308 bolt rifle?

    David.



  • Spoke with Dave Manson and got the information I needed. Has a identical body as SAAMI .308. Difference is parallel neck at .3420" instead of .3462" at neck/shoulder junction tapering to .3442" at case mouth. Don't rember the exact numbers of the freebore he told me. It should allow for a 168 smk to touch the lands at 2.820 COAL. Think that works out to a few 0.0500" freebore. SAAMI spec is 0.0900". Dave also said it should work great to magazine feed 175 SMK and Berger VLD's in a ACIS magazine.



  • I've always been a fan of the bisley chamber in 308. :)



  • Local gunsmith boogered up my FN PBR XP bolt knob. So he replaced the entire bolt body with a bolt out of a new FN SPR action. Head space is wrong so he is going to set the barrel back and recut the chamber. He said he would use the M852 reamer rather than a SAAMI one. He told me what the difference in the two were, but I wanted to check for myself. Also wanted to make sure all my current components would be compatible.



  • @drandi

    Stop using that gunsmith.

    If he can't thread a bolt for a knob, I don't know if I'd trust him to chamber and headspace a barrel.



  • @drandi said:

    Local gunsmith boogered up my FN PBR XP bolt knob. So he replaced the entire bolt body with a bolt out of a new FN SPR action. Head space is wrong so he is going to set the barrel back and recut the chamber. He said he would use the M852 reamer rather than a SAAMI one. He told me what the difference in the two were, but I wanted to check for myself. Also wanted to make sure all my current components would be compatible.

    Whew. I hope you know that it's fairly tough, if not nearly impossible to get a barrel with a chamber on it centered up in a lathe. Raw access to the lands either with an extremely high quality range rod or an indicator needle itself is desirable. If a chamber is already cut, most range rods won't reach, and if they do they will flex a lot. If you try to get concentric off the chamber itself, then you're dialing in on something that probably wasn't super concentric to begin with and even if it was, you're dialing in on whatever tolerance existed for the original chamber job. Not optimal.

    I'll tell you outright, when I got started in this I had a few projects messed up by people claiming to be gunsmiths. There are lots of unremarkable people out there that claim to be a thing that they really aren't. Most gunsmiths out there have a hard enough time getting a chamber in right in the first place, much less trying to plug one in after one already exists. You'd be doing yourself a favor to call @tscustoms and shift your work over to him. It'll save you thousands in the long haul and each job will be done right. At least call him and get his opinion on this.



  • All of those thoughts crossed my mind. The "repair" is on hold till the 9th. It was already agreed upon if it doesn't go well he is giving me a new barrel blank. If anything happens to the action he has a new in the box FN SPR action to replace my FN PBR action with.

    Even though the raw actions are the same, the SPR roll mark carries more weigh on the resale market. So I guess there is some piece of mind there.

    He was going to cut the barrel back .300" inches, recut the tenon, and then recut the chamber with a Manson carbide M852 reamer.

    The shop is Dow Arms Room. The Shop owner and head gunsmith is Bruce Dow. Bruce is not the one who fudged the bolt knob, but one of his shop apprentices. Bruce was very nice and receptive to try and make it right. He replaced the entire bolt with a new one of my choosing out of a FN SPR action. He refunded my money for the bolt knob and said he would headspace in the new bolt for free when he returns from family business. So do you think I should let him try?

    I thought about suggesting I buy a new barrel blank and he chambers it for free, (not trying to be a dick and roll him over even though his shop made the mistake) as it's the same setup work and probably easier to indicate off.

    The barrel is a factory FN PBR XP 20" in .308. Do you think it's worth all this hassle to have it fixed, or just bit the bullet buy a new blank and pay someone else to put it together the right way?

    Yes I'm bitting at the bit on this and not sure what to do. On one hand it's a cheap factory barrel, but it's the only one I have right now. I was originally planning to shoot this barrel out. Then have the action trued and barreled in 6.5 Creedmore, .260 AI, 6.5 Super LR.....or something along those lines.

    Problem is life was very very expensive this year and don't have much for extra funds.....I know, hard to work with that one.

    So I guess bottom line is do I let them have a go at correcting it, or just take my parts and wait till I can afford for TS Customs to put it together?

    David



  • @drandi said:

    or just bit the bullet buy a new blank and pay someone else to put it together the right way?

    ^^^^^^
    Call TS Customs and quote out a build. Factory barrels are factory barrels. You'll have a shorter one with far less likely to have a straight chamber in it. This crap will be in your mind EVERY time you miss. That is why it's so important that smiths do things right the first time. Getting that confidence back is sometimes impossible for people.

    Collect your parts from that smith and get them to TS Customs. Consider it a lesson learned. Call Travis and talk it out. You'll be happy you did.



  • Get this smith to give you whatever the cost of the chamber job would be.

    That seems fair.

    He'll break even and you're only out the cost of the blank.



  • Talked with Travis at TS Customs and have my direction now.

    I'm just going to cut my losses, and cal it a day. I'm going to have him spin the original barrel off and just give me my parts back. Bolt has been replaced with a brand new FN one, so the hard part is taken care of.

    Guess my mother in law has a expensive stake for her flower garden. 😏

    Now, do I stick with .308 since I have forester and reddings dies, 100 pieces of twice fired fully prepped Lapua .308 cases and 550 Nosler 175 RDF projecites, or move to some 6.5mm goodness?

    Travis has a 6.5 Creedmoor reamer setup for 140 gr projectiles to touch the lands and still freed from a ACIS mag.......🤔



  • If I only had one rifle, I'd go for a 6.5CM. More versatile than 308.



  • That's what I'm think too. Anyone wanna buy some .308 reloading dies and components........😏

    David.



  • I'd keep them. You never know when you'll want to go back to it. :)



  • I would change calibers too. I like my 308 barrel but would buy a 6.5 cm if I was buying it today.

    Components are temporary and should not determine caliber. In my opinion.


 

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