rechambering 22-250 to 22250imp
- Thread starter jofus
- Start date
jofus
treeman is not quite right. If you want to convert it to a legitimate improved chamber that means that it will take factory cartridges as well as improved cases. To do that you have to set the barrel back one thread and then rechamber using the go gauge as a no-go. At least .004" short headspace. Otherwise you will not have an improved chamber. A wildcat, yes.
Not that there's anything wrong with simply running in the improved reamer. But if you mark the barrel "22-250 Improved" think of the next guy who owns that rifle not knowing what the chamber really is.
JMHO
Ray
treeman is not quite right. If you want to convert it to a legitimate improved chamber that means that it will take factory cartridges as well as improved cases. To do that you have to set the barrel back one thread and then rechamber using the go gauge as a no-go. At least .004" short headspace. Otherwise you will not have an improved chamber. A wildcat, yes.
Not that there's anything wrong with simply running in the improved reamer. But if you mark the barrel "22-250 Improved" think of the next guy who owns that rifle not knowing what the chamber really is.
JMHO
Ray
Ackman
Gold $$ Contributor
If you want to do it right, the barrel should be set back.
Headspace needs to be less....there should be some pressure on the bolt handle when chambering a round. It's called "crush". It's not pushing the whole shoulder back, just the neck/shoulder junction radius where it hits the case. The amount of crush is up to you and that generally quoted .004" really isn't enough. Brass can vary by more than that and there should be enough to get a good seal with every case. You can actually go quite a ways with crush.....mine have about .025" which many people would say is excessive, but it works very well.
Factory chambers can be generous......if the existing chamber's back end is larger than the AI reamer, you'll wind up with a chamber that has two body tapers.
If the existing chamber is factory or even standard SAAMI, you'll want a new throat with less or no freebore. Also, most chambers are much-much longer than the brass and AI cases don't stretch. With a rental reamer you don't know how many times it's been used, how sharp it is, and what the dimensions are. Done right a 22-250AI can be very accurate and fast. If you really want to do things right, spec out a reamer to fit your brass and have one made. It's worth the cost. You'll know exactly what it is and how many chambers it's cut.
Headspace needs to be less....there should be some pressure on the bolt handle when chambering a round. It's called "crush". It's not pushing the whole shoulder back, just the neck/shoulder junction radius where it hits the case. The amount of crush is up to you and that generally quoted .004" really isn't enough. Brass can vary by more than that and there should be enough to get a good seal with every case. You can actually go quite a ways with crush.....mine have about .025" which many people would say is excessive, but it works very well.
Factory chambers can be generous......if the existing chamber's back end is larger than the AI reamer, you'll wind up with a chamber that has two body tapers.
If the existing chamber is factory or even standard SAAMI, you'll want a new throat with less or no freebore. Also, most chambers are much-much longer than the brass and AI cases don't stretch. With a rental reamer you don't know how many times it's been used, how sharp it is, and what the dimensions are. Done right a 22-250AI can be very accurate and fast. If you really want to do things right, spec out a reamer to fit your brass and have one made. It's worth the cost. You'll know exactly what it is and how many chambers it's cut.
The only AI chamberings I feel comfortable doing w/o setting the barrel back are rimmed cartridges.
Look at it this way: how will you know how far is too far? With the barrel already chambered in 22-250, the bolt will close on a "go" gauge before any reaming is done.
Why chance it? Just set the barrel back one thread and do it right.
Tom
Look at it this way: how will you know how far is too far? With the barrel already chambered in 22-250, the bolt will close on a "go" gauge before any reaming is done.
Why chance it? Just set the barrel back one thread and do it right.
Tom
It really is a huge mistake to simply run an improved chamber into an existing chamber without setting the barrel back. The head space dimension is taken from the case head to a datum point on the shoulder between the neck and the sidewall. Since you are fire forming standard brass the improved chamber needs to have the same head space as the standard chamber. Simply running an improved reamer into a standard chamber moves the head space datum forward enough that there is a high probably of case head separation when you fire form brass. As stated earlier the correct way to improve a chamber is to set the barrel back and use the go Gage as a no-go Gage.
Tommie
"Look at it this way: how will you know how far is too far? With the barrel already chambered in 22-250, the bolt will close on a "go" gauge before any reaming is done."
Dont understand why you cant measure the headspace of the original chamber, sounds like you chamber rifles relying on the feel of the bolt on the go gauge and heaps of engineering blue to determine bolt clearance?:,
wal
"Look at it this way: how will you know how far is too far? With the barrel already chambered in 22-250, the bolt will close on a "go" gauge before any reaming is done."
Dont understand why you cant measure the headspace of the original chamber, sounds like you chamber rifles relying on the feel of the bolt on the go gauge and heaps of engineering blue to determine bolt clearance?:,
wal
Upgrades & Donations
This Forum's expenses are primarily paid by member contributions. You can upgrade your Forum membership in seconds. Gold and Silver members get unlimited FREE classifieds for one year. Gold members can upload custom avatars.
Click Upgrade Membership Button ABOVE to get Gold or Silver Status.
You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.
To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.
Click Upgrade Membership Button ABOVE to get Gold or Silver Status.
You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.
To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.