I hope I have this in the right sub-forum ....
I am thinking toward a custom XP build, but caliber has not yet been decided.
Obviously if I decide on a .473" bolt face a donor action with the correct bolt face (7BR or 35Rem) eliminates the need for alteration.
My question is if I decide to move to a .532" bolt face cartridge, is there any advantage to starting with a .473" bolt face, vs. a .378" bolt face?
My concern would be with the location of the ejector on the smaller bolt face being incorrectly located for proper function on a larger diameter case.
I guess I have the same concern over opening a .378" bolt face to accept the standard .473" class of cartridges.
Also to make this a 2 part question, is there any practical advantage to a mini M-16 style extractor over a Sako style extractor?
I personally prefer the look of the M-16 style, but understand it requires a little more machining.
Thanks in advance,
Good questions! The ejector is the same distance from the centerline on all of the bolts so that is a non issue. I prefer the M-16 style extractor but it does require clearances for the extractor to be able to “snap” over the rim of a cartridge. In other words the counterbore in the barrel for the bolt nose must have additional clearance. The .223 bolt face will clean up easier without a bushing but almost any of them can be made to work with a little effort.
Contender 22LR, 17MachII, 17HMR, .223(SSK), 6mm Gator, 6TCU, 6mmJDJ(Van Horn), 25x47(Coyote), 6.5 JDJ(SSK), 7x47(SSK),308 Bellm, .338 SSK Woodswalker (2),358 Bellm, 375Win, 375 JDJ(SSK), 45/70(SSK), 45/70 (VanHorn), 50-70(SSK)
Encore .243, 7mm–08, 300WM(15-1/4"), 50-90(MGM, 14"), 50–110 (MGM), .50ML(16")
XP-100 .223, .223AI, 6mm204Imp, .243AI, 6BR
XP-7 .223,.243,.300Blackout, .300RSAUM
XP-700SA .22LR, .243
XP-700LA .25/06, .270AI, .300WM,.338 Lapua, .510 Whisper
Thank you for the response, that is exactly the information I was looking for.
Also thanks for explaining the counterbore requirements for the M-16 style extractor.
Either bolt size would work out. To get everything to work correctly the bolt face
Should be bushed. Not doing that is a gamble.
I had planned to have it bushed, based on previous discussions I had seen on this and other forums.
Are you saying that the .378" bolt face wouldn't clean up if you opened to a magnum? I know they don't for a .473"
It might. It might not. Depends which day they cut the extractor slot at Remington
That is an interesting question.
I understand the bushing eliminates the little bit of recess left if you open a small bolt face to standard, eliminating the chance for the rims to hang during extraction.
But .... If you open a small bolt face to magnum, would that remove all the recess for the extractor? If so is there an advantage to going even larger and then bushing down to .532"?
It seems to me that if opening the bolt far enough to remove all traces of the extractor recess then the bushing serves no purpose.
Please correct me if I'm wrong or missing something.
Educational discussion for me so far so thanks to all who have posted.
Just me thinking but would this be a time to consider a PTG bolt and save the original in case you want to come back to the original bolt face?
That is a valid point, especially if the cost to alter an existing bolt and the cost of buying and fitting a new PTG bolt are reasonably close.
For me the cost isn't a factor. But I have the tools to do the work myself. I've opened up a few bolts and so far they've cleaned up by the time I got big enough for magnum. Haven't done a pile of them though. If you are just going to a .473 then you should bush it for sure. A buddy had a smith that just put in an m16 extractor and the rim would catch in the old groove and not eject the case. One other consideration is wether or not you're going to have the bolt body sleeved to tighten that up. If your paying someone to do that work you would be money ahead to get a PTG with the correct diameter.
One thing about two bolts it would allow you to do a switch barrel set up.
My main issue with getting a PTG bolt is ordering the correct bolt. There are several specific measurements that are required to order a bolt, and I cannot figure out how I would get reliable trustworthy measurements with the tools and knowledge I have. It looks like I would need to invest in $100+ worth of tools just to bet the right bolt ordered.
An investment in that tool would probably be worth it for a gunsmith. That doesn't seem worth the expense for the limited use the tools would see for my personal use.
Heck, I'd bet a gunsmith or machinist has all sorts of tools to make proper measurements, but I am neither.
I am also entirely new to any sort of custom build.
I am operating under the (probably incorrect) assumption that I would obtain all the parts I wanted for the build and then drop them off to have a gunsmith properly match and assemble them.
If making the correct measurements and ordering the right parts is all part of the build, then I guess that contributes to why builds take so long. Your gun sits at the shop while the gunsmith waits for parts, just like I would be waiting at home.
I am just starting down this path and want to learn as much as possible, before I take the next step.
Many ways it can be done. I know smiths who will measure and order the correct bolt. They normally ask that you put money down to cover the cost of those parts so that they're not out anything if you back out. You could simply mic the bolt body you have and order a bolt the same size, with the correct bolt face and extractor you want.
I had considered micing my current bolt, but that would forfeit any improvement to fit.
My thought is if ordering a custom bolt then I would want to take full advantage of a custom fit to the action.
Have you called the smith you intend on using? See what they recommend. IF the smith has a reamer to ream the raceway then you order a bolt that's .001" smaller. The common raceway reamer PTG sells is .705". So I'd recommend ordering a .704" bolt body.
I prefer to sleeve the body on my bolts. Part of the reason is cost. I do my own work vs buying PTG bolts. Second is I don't like dealing with PTG. And third is when the whole bolt body is .001" under the raceway dimension the bolt doesn't have much wiggle room while cycling the action. So if you've got a long bolt handle or knob you can put the bolt in a bind while cycling it. The sleeves aren't very long so they don't bind up the same way. Also I file/stone the sleeves so they are the same diameter as the bolt while the handle is up. So they are kinda egg shaped and only tighten up the fit when the handle is in the down position. That combined with reaming the raceway larger than factory makes for a sloppy and fast cycling bolt while still taking ALL the play out when its in battery.
But in all honesty if this isn't a benchrest rig I wouldn't worry about making the bolt body .001" smaller than the raceway. I don't believe its possible for 99% of shooters to realize the potential in anything other than a full benchrest set up especially in field shooting. Weird awkward positions and general field conditions aren't conducive to the little itty bitty groups the BR guys shoot from time to time.
AaronThis message has been edited. Last edited by: rickiesrevenge,
Thanks again for another thoughtful response, I do appreciate that.
Right now I feel I am so far from starting that I don't want to burden a gunsmith with questions (luckily this group seems willing to take on the burden of my questions).
My approach so far has been to gather information and knowledge of the general process and decide on what I want. Then I will call some gunsmiths to talk about the project, and see who I feel comfortable with.
Then I can workout the details with that particular smith.
|Powered by Social Strata|