Gunsmithing Head Spacing a 243AI

[Capt Beach]

Rebarreling a Savage 110 308 to 243AI...I've just decided to buy a set of .243AI Head space gauges...I've been told that all I have to do is buy a 243AI GO gauge as the regular 243/308 GO gauge will function as a NO GO GAUGE for the 243AI...is this correct?

 

[GasLight]

you don't really need a no-go gauge at all, but yeah you should be set with that setup.

 

[matthias]

Just get the set for 243 ai. Do you need the set? Nope but, You will know without a doubt you are good.

 

[Capt Beach]

Just get the set for 243 ai. Do you need the set? Nope but, You will know without a doubt you are good.

What I am trying to avoid is duplication...if the dimensions of the 308/243 GO gauge are the same as a NO GO gauge for a 243AI why should I buy a complete set of GO/NO GO for 243AI...I'd have two gauges the same size when all I need is the one 243AI GO and use the 308/243 GO as a 243AI NO GO... if I am correct...follow me?

Capt Beach

 

[GasLight]

if you have interest in saving money and avoiding duplicity, then don't buy a no-go gauge. You don't need it. You can use a piece of feeler gauge or even scotch tape to see if you are just over Go. You want to be as close as possible to this gage anyway. Chamber tight enough that the bolt won't close on go with a piece of tape on the rear of it. I like to use a feeler gauge because it is more accurate, I trimmed a piece off my .002" feeler, and put that on the bolt face, and then make sure the bolt won't close, tighter than no-go. If I am not within .002" of go, I am not happy. Close on go, won't close with feeler or tape behind it... YMMV

 

[2156SMK]

What I am trying to avoid is duplication...if the dimensions of the 308/243 GO gauge are the same as a NO GO gauge for a 243AI why should I buy a complete set of GO/NO GO for 243AI...I'd have two gauges the same size when all I need is the one 243AI GO and use the 308/243 GO as a 243AI NO GO... if I am correct...follow me?

Capt Beach

The AI gauges have a completely different SHOULDER angle.
While the AI is shorter by a bit, the angle is different.
The only ACCURATE way to measure chamber depth is with a gauge using the proper angle.
If you are trying to save money by not buying all the proper tools for the job, get some 0.003" steel shim stock and make yourself a little washer to put under the "GO" gauge to convert it to a "NO-GO" gauge.

 

[matthias]

http://benchrest.com/showthread.php?55807-243-AI-headspace

This is the reason the last three ai rifle I built I used a set of gauges from the reamer maker. Easier and the duplicity does not bug me. With standard cartridges I use the technique mentioned above with a feeler gauge. More of a why make things more confusing . Just my $.02

 

[Capt Beach]

OK...buying a 243AI GO GAUGE...so the consensus is .002 or .003 on the shim stock/feeler gauge? to add as a NO GO...

Any recommendations on Head Space Gauges?

 

[matthias]

I use pacific tool and gauge all the time. Just bought 22k hornet and 5.7 reamers with matching gauges. I think they were 27 plus shipping

 

[LRI]

Ackley 40* rules:

The parent cartridge GO gauge becomes the NO GO gauge. This is because Ackley cartridges are shorter than the parent cartridge.

The parent cartridge should have a .004" interference when chambering to fire form. This ensures the neck/shoulder junction of the case is pinched to ensure that the cartridge is firmly seated against the bolt face.

This mitigates case growth in the critical web region of the case. It has no choice but to expand/inflate and rob material from the neck/shoulder area of the case. Failure to observe this results in hour glassed case webs and dramatically reduced service life of the cartridges when reloaded.

When "Ackley Improving" a barrel already chambered one MUST set the barrel back at least .0625" to achieve proper case pressure when the bolt is closed. This is where the term "taking off a thread" comes from as 16 threads per inch (.0625") is a very common pitch used for barrel tennons.

SO, you can buy your Ackley GO and use the 243/308/260/7-08 GO as the NO GO.

Hope this helped.

C.

 

[Capt Beach]

Thanks Chad I will follow your advise here...YOU actually cerakoted the new (to me) barrel flat black and a local (to you) Leo Schnell at Precision Arms did the chamber conversion from 243 to 243AI...he also added a 5/8 x24tpi threading for a muzzle break...the barrel was a large shank Savage 12 LRPV that Leo also turned down to small shank specs...she sounds like a shooter...I get her Friday...ordering a PTG 243AI GO gauge in the am...thanks...

Semper Fi

Capt Beach

Ackley 40* rules:

The parent cartridge GO gauge becomes the NO GO gauge. This is because Ackley cartridges are shorter than the parent cartridge.

The parent cartridge should have a .004" interference when chambering to fire form. This ensures the neck/shoulder junction of the case is pinched to ensure that the cartridge is firmly seated against the bolt face.

This mitigates case growth in the critical web region of the case. It has no choice but to expand/inflate and rob material from the neck/shoulder area of the case. Failure to observe this results in hour glassed case webs and dramatically reduced service life of the cartridges when reloaded.

When "Ackley Improving" a barrel already chambered one MUST set the barrel back at least .0625" to achieve proper case pressure when the bolt is closed. This is where the term "taking off a thread" comes from as 16 threads per inch (.0625") is a very common pitch used for barrel tennons.

SO, you can buy your Ackley GO and use the 243/308/260/7-08 GO as the NO GO.

Hope this helped.

C.