Basic (dumb) action question

[davidmcintyre]

Hi everyone. I've been reading these forums for a long time, and I'm starting to think about building a rifle for myself. I'm looking at using Gary Eliseo's R5 system, build for 6mm BR.

I've been looking at a lot of custom action builders, and I can't quite figure something out. Do actions come in calibers? Or is in the bolt? Or just the ejector, or?

If I look at a typical custom short Remington style action, like BigHorn Arms, or Pierce, or Borden (or anybody), they have various models, different features, varying prices, but they don't say anything about the caliber? Here's a typical bolt description page:

http://www.pierceengineeringltd.com/products.php?item=2

But nothing about calibers.

So, does this stuff work for all calibers? That doesn't seem right to me. What do I need to check to make sure a custom bolt will work in the caliber I'm looking to build?

Thanks, Dave

 

[Dennis Sorensen]

I would order by cartridge designation.

For instance a short action would serve 3 different bolt face sizes.. but you would need the bolt to be specific for a .222 or a 6mm PPC or a 6mm BR... and then in the case of a repeating action rails need to be machined for the cartridge. The same with a long action for a standard .06 case or a standard Magnum case.

 

[alinwa]

OK,

Dennis is right but I'll try to answer this specific part of your question in a way that I hope clarifies your decision......

"So, does this stuff work for all calibers? That doesn't seem right to me. What do I need to check to make sure a custom bolt will work in the caliber I'm looking to build?"

"Caliber" is specifically the diameter of the rifled bore.... it has almost nothing to do with your choice of action, only with your choice of bullet.

"Chambering" though, or your chosen "cartridge case" are important.... nearly identical chamberings may come in different calibers. For instance, the .243Win and the .308Win share the same case, nearly the same chamber, and can be cycled through the same actions. A .243 action will always work for a .308 and visey-varsey..... or a .7mm-08 or a .260 or a number of wildcats and other rounds based on the .308 case. Another example would be 30-06 and .270, same deal...... same case, different calibers.

If you are asked to help spec an action you need to consider several factors. 1st is boltface diameter. Look at a book of cartridge diagrams to find something called "head diameter" or "casehead diameter." This dimension determines the diameter of the boltface. The boltface is typically recessed and must be fitted such that your choice of cartridge slips into the boltface and engages the extractor. The .308/.243 example used earlier would use what is typically designated a ".473 bf" although various mfgrs vary this number a few thou. A .473 bf accommodates a whole slew of American cartridges, those based on .308 and 30-06 as well as 22-250, (.250 Sav) .257 Robts, 6mm Remington etc........

Note that while extractors/ejectors aren't typically considered to be caliber-specific, extractors and ejectors are very different things. (you use "ejector" above) and the sizing of an extractor ties into bf size and as such will be spec'd by use of the appropriate boltface.

Next is length. I mentioned the .308/.243 and the 30-06/.270 as sharing casehead size......... they can be accommodated by the same boltface but obviously the 30-06 case is much longer than the .308 case. This necessitates a longer action. The Remington 700 SA (short action) fits the .308 family of cartridges while the 700 LA (long action) is designed for 30-06 length cartridges.

sooooo, that's boltface and length....... this covers single shot target style rifles. NOW we get into details. If the rifle is a repeater then a whole bunch of other detail factors come into play. There's not room here for any sort of discussion of the parameters involved in getting cartridges to feed from the magazine. Suffice it to say that listening to Dennis is particularly hoovis when it comes to repeaters.... let the action mfgr make this call!


so back to your question.. "does this stuff work for all calibers" .... I guess the short answer is "YES" because you pick your action based on case dimensions, not caliber.

Or, as Dennis so succinctly put it, "pick your action based on cartridge designation."

hth


al

 

[davidmcintyre]

Thanks for the assistance. I just received my Pierce Engineering custom tube gun action, which is beautiful, and had them attach my Hart barrel, so I'm rolling along now. R5 kit should be arriving via UPS today or tomorrow. I have another scope question, which I'll post separately.