.243 AI Loading Question

[westcliffe01]

Tom, Greg should get his chamber cast, or simply have the throat dimension measured by a reputable gunsmith. If his throat is too long, he would not be able to do what is usually recommended in his situation, which would be to drop down in bullet weight until they stabilize. He is limited on the upper end by the twist rate, which is inadequate for the bullet weight he intends to shoot and also limited on the light end by a too long throat. Possibly his throat is a limiting factor in his shooting the 95gr bullets too.

I don't know how long he has had this weapon, but any gunsmith who made such a bad chambering job, should fix it for free. This is a systematic problem. I have been shooting my 243AI with H100V and it shoots great, but I know for a fact that shooting the exact same components in my 1:9.25 factory barrel (same length) the stability was sufficiently marginal that all my groups opened up to around 2". This sounds like exactly the situation Greg has (needs extreme pressure to spin the bullets fast enough). And it is probably still going to be marginal and likely not a safe way to be doing things.

 

[TOM H]

Tom, Greg should get his chamber cast, or simply have the throat dimension measured by a reputable gunsmith. If his throat is too long, he would not be able to do what is usually recommended in his situation, which would be to drop down in bullet weight until they stabilize. He is limited on the upper end by the twist rate, which is inadequate for the bullet weight he intends to shoot and also limited on the light end by a too long throat. Possibly his throat is a limiting factor in his shooting the 95gr bullets too.

I don't know how long he has had this weapon, but any gunsmith who made such a bad chambering job, should fix it for free. This is a systematic problem. I have been shooting my 243AI with H100V and it shoots great, but I know for a fact that shooting the exact same components in my 1:9.25 factory barrel (same length) the stability was sufficiently marginal that all my groups opened up to around 2". This sounds like exactly the situation Greg has (needs extreme pressure to spin the bullets fast enough). And it is probably still going to be marginal and likely not a safe way to be doing things.

I don't disagree with you but Greg had a rifle rebarrel and someone had to decide on who's barrel what twist and chamber to use? I know gunsmith who build my 243AI asked lot of questions.

When you get on open forum trash gunsmith about the wait etc also give his name could see why Greg isn't calling him.

 

[westcliffe01]

Well, if the gunsmith has proof that the buyer asked for a longer than Sami throat, he would be all set. Somehow I find that very hard to believe though. Many people who have a smith build there gun wouldn't know what a SAMI throat looked like. All the prefit barrels being made out there will have a standard throat dimension unless specifically stated otherwise.

There are plenty people on this forum claiming that you can shoot heavy Berger bullets from their 1:10 barrels, but I chose to believe Berger when they say it needs a 1:8 twist or that it is simply better to be conservative and get "more" twist than you absolutely need so that one is never working with marginal stability.

What kills me about this whole discussion is that factory barrels are available with a 1:9 twist so Greg could have avoided the entire custom rifle thing by just choosing a suitable starting rifle and would have saved a ton of money too. Then when he found that the 1:9 twist was not working for him, he could have gone to a lighter bullet, or what he needs to do now, re-barrel with a 1:8. Buyer beware of shelling out a lot of money on a custom gun based on advice received on the internet. Take a look at what kinds of match barrels are actually selling for your caliber. In 243 it is the 8 twist because of the fact that you can't get one from the factory. Read 6mmBR to see what competition shooters are using. You won't find anyone listed there shooting a 1:0 or 1:9 barrel except for varmints with light bullets, but you will find 1:8 and 1:7.5 for shooting the 115gr DTACS. Be guided by people getting verified results, not internet jocks like me....

 

[Greg Duerr]

This whole thing has been a live and learn experiance............................I think if I had to do it over I would have bought a Copper ....................and would not be here right now asking all these quesions, instead I would be out shooting Marmonts and Jackrabbits..........................and would have been hundreds of $$ better off.

I did order a new pair of Digital Calipers so I can varify things a little more accuratly...............


Greg

 

[westcliffe01]

My lathe bed is in the shop getting re-ground, when I get that back I have to re-work the saddle and replace the lead screw. Finally I will have a nice heavy lathe and will be able to do my own threading, chambering and crowning. A typical reamer is $100 and a simple blank is substantially cheaper than a pre-fit. There are places one can rent reamers too.

I was just looking at the Shilen website and unless I am missing something they just had a huge price increase. $449 for a Savage pre-fit ? I just paid $329 for my 243AI a couple of months ago at NSS. I noticed the same thing at a few other barrel makers... They still list blanks for $248 for the match grade.

 

[Kelly Jackson]

Greg - I have four 243AI's. Never seen a 9 twist that would not shoot a 105 Amax.

H4350 is what I use most of the time with that bullet, R17 will push it faster.

Also am able to run 115Dtacs in both a 7.5 twist and 8 twist barrel with the AI.


Note: the 105Amax can be jumped a long way and still shoot great.

Before you do anything you might want to give H4350 and the 105's a chance.

Regards
Kelly

 

[Greg Duerr]

Kelly

you sound like the guy I need to walk me through the learing curve for the .243 AI

I just bought some H4350 and was going to try some 90gr ballilstic tips as im not sure my 1x9 is working out for me using the 95gr berger. I do have some 105 amax and will still try those.......................Im curious about the 90gr as it will work with a 1x10 Like I said I could not get any accuracy not until my charge hit high pressure. I can get the 90 gr BT to touch the rifleing as when using the 95gr berger I could not........................

Whats your email address..................I would really appreciate your knowlege.

Greg

[email protected]

 

[Kelly Jackson]

email sent Greg.