Discussion in 'Gun Project Questions & Gunsmithing' started by maddysdad, Dec 13, 2019.
how do you true up a rimfire action
Whats different on a centerfire? It has threads (in the end) that have to be concentric to the bore, lugs need contact, bolt face should be straight along with the front ring and lug if it has one on the front- typical of any action.
40 x remington
can any bench rest gunsmith do this and fit a barrel
Not many cross over. Its a whole different world. Im sure some do but it seems like the good rimfire guys concentrate there. I cant think of any centerfire guy that does rimfire too
Mark Penrod from Indiana who is a real good smith does both rimfire and centerfire.
Gene Davis is the 40X man!
As a rule, Smiths typically specialize in either centerfire or rimfire accuracy. There are some accuracy steps that are the same between disciplines (Pillar bedding for instance) and some that are completely different . Fitting a rimfire bbl has a lot more variation that typical centerfire. Centerfire actions are threaded to accept the bbl, many rimfires are not. Barrel break-in with a centerfire is often done with live ammo, rimfire utilizes lead bullets that are not capable of performing the same break-in job as a jacketed bullet.
If ultimate accuracy of the rimfire is the goal, it would be best to seek out the Smith who is accomplished in the details of the rimfire. If this is just a plinker, then that changes the game and makes life easier.
I have done several and there are a few things that make a 40-x rimfire action significantly more difficult to true up than a centerfire. First its lug abutments in the receiver are behind the loading port rather than immediately rear of the barrel threads. Fixtureing the receiver to machine the abutments requires a different setup and tooling that allows for the long reach back in to the lugs. It's a heck of a lot more of a challenge to do that procedure as compared to a centerfire.
The two piece bolt presents it own set of issues. The rear half of the bolt, where the lugs are, is so short that holding it, and having enough room to machine the bearing surface of the lugs, requires a separate fixture of its own. It took me somewhere in the neighborhood of 6 hours to make the fixture to hold the bolt half, and 30 minutes to set it up, to do the 10 minute machining. Both bolt halves mating surfaces must be machined. A centerfire bolt doesn't have those mating surfaces.
Headspace is an issue with the 40-x. If you are a believer that headspace should be in the .041 to .043 range then the bolt nose needs some attention. The counterbore in most 40-X's is around .043 so to have a proper clearance of bolt nose to barrel tennon the bolt nose needs to be shortened by about .005. I did that with a tool post grinder.
It takes me at least 2X as long to true up a 40-X rimfire as to do a centerfire action.
what would be a great custom action then
Very comfortable with rimfires. It's where I began in the game 27 years ago.
Happy to help.
Gene is a pretty good guy but he has not built anything that has won anything in several years.
BINGO! The only custom BR grade action that needs nothing.
If a guy is unaware of what some of these things may require and who, in particular, is adept at doing it, they are far more likely to have a successful build on a 2500X.
It remains the only RF action I ever heard of where you can swap a barrel from another properly fitted 2500X and have it fit, headspace, and extractor slots line right up. Stiller’s tolerances are that good.
Tim, If you have 90% retired, it is hard to have the winners. He has done a couple 40X tin can shooters and his work is just over the top!
no argument there, I am very familiar with his work, bought a fair amount of ELEY from him as well.
The point was the OP was asking about a comp gun and there has been constant change, particularly on how to fit and evaluate some of the current barrels. Everything is constantly changing, know of absolutely zero actively competitive shooters basing anything off of a 40X these days, and one of our local guys and good bud of mine did pioneering BR work with them making IR 50 sporters converting them to repeaters and converting them to 6 o’clock firing pins.....that there is some piece of work.
Hey Tim what mag do those 40x repeaters take?
I believe they were set up for Sako mags, but remember the IR sporters required a mag but they would nod feed mostly because of a full match chamber. He only did, maybe, 5-6 before he waved the white flag. That’s when Alan Hall came with the first full on BR sporter actions.
Separate names with a comma.