Forums
New posts
Search forums
What's new
Articles
Latest reviews
Author list
Classifieds
Log in
Register
What's new
Search
Search
Search titles and first posts only
Search titles only
By:
New posts
Search forums
Menu
Log in
Register
Install the app
Install
Forums
Rifles, Reloading, Optics, Equipment
Reloading
Is it possible NOT to get accuracy from A-max 162?
JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an
alternative browser
.
Reply to thread
Message
<blockquote data-quote="westcliffe01" data-source="post: 1158228" data-attributes="member: 35183"><p>With any sufficiently long bullet, you should be able to regulate the distance from the chambered position to the engagement with the rifling lands. I do not hear that is your problem. With a boat tail bullet, if the throat diameter is too large, the back of the bullet may not be guided adequately when it leaves the mouth of the cartridge. The guide length (cylindrical length)of a flat base bullet is longer than the guide length for a similar weight boat tail bullet and sometimes the pressure acting on the base of a flat base bullet might even expand it a little, leading to a better guide.</p><p></p><p>This issue with the throat diameter is usually the reason why you have problems with any form of boat tail bullet, yet flat base bullets will shoot fine. Of course there are many additional things that can go wrong when chambering a barrel. The chamber may not be aligned with the bore. Sometimes there is no throat and the rifling ends with a square edge. These things can be measured with a dial indicator and observed with a borescope system. But it is quite tricky setting up a barrel so that the bore actually runs true on both ends, especially when there are 3-5 rifling lands to mess around with the dial indicator.</p><p></p><p>1000 rounds is not a huge amount through a 7mm-08 but there will still be some wear in the throat, so that is going to make the job of diagnostics difficult at this point. </p><p></p><p>So again, the easiest way you will pin point a well known issue like the throat diameter will be to shoot a box of 20 flat base rounds and see how much better they do than your reloads.</p><p></p><p>If this confirms the issue, you will either have to adapt to shooting flat base rounds, or, have the chamber set back - with specific instructions regarding the type of bullet you are planning to shoot, or, buy a replacement barrel and specify exactly what bullet you plan on shooting and you might want to review some reamer specifications to that you can specify the diameter throat that you need with a tolerance.</p><p></p><p>If a barrel is rifled and then lapped, it is normal that the last few inches of the blank at both ends would be oversized from the lap reaching the end of its stroke and not being properly guided. I don't know if your barrel maker laps the blank or not or if he did, perhaps did not remove enough material to get back to a "good" bore diameter. These are some of the mistakes that can be made when making match barrels, but the supplier should know these risks very well and be taking care of what is important to you. So far I have bought several Shilen barrels and not had a problem with an oversized throat on any of them. In fact, the only problem so far is that one throat was undersized. Opposite problem...</p></blockquote><p></p>
[QUOTE="westcliffe01, post: 1158228, member: 35183"] With any sufficiently long bullet, you should be able to regulate the distance from the chambered position to the engagement with the rifling lands. I do not hear that is your problem. With a boat tail bullet, if the throat diameter is too large, the back of the bullet may not be guided adequately when it leaves the mouth of the cartridge. The guide length (cylindrical length)of a flat base bullet is longer than the guide length for a similar weight boat tail bullet and sometimes the pressure acting on the base of a flat base bullet might even expand it a little, leading to a better guide. This issue with the throat diameter is usually the reason why you have problems with any form of boat tail bullet, yet flat base bullets will shoot fine. Of course there are many additional things that can go wrong when chambering a barrel. The chamber may not be aligned with the bore. Sometimes there is no throat and the rifling ends with a square edge. These things can be measured with a dial indicator and observed with a borescope system. But it is quite tricky setting up a barrel so that the bore actually runs true on both ends, especially when there are 3-5 rifling lands to mess around with the dial indicator. 1000 rounds is not a huge amount through a 7mm-08 but there will still be some wear in the throat, so that is going to make the job of diagnostics difficult at this point. So again, the easiest way you will pin point a well known issue like the throat diameter will be to shoot a box of 20 flat base rounds and see how much better they do than your reloads. If this confirms the issue, you will either have to adapt to shooting flat base rounds, or, have the chamber set back - with specific instructions regarding the type of bullet you are planning to shoot, or, buy a replacement barrel and specify exactly what bullet you plan on shooting and you might want to review some reamer specifications to that you can specify the diameter throat that you need with a tolerance. If a barrel is rifled and then lapped, it is normal that the last few inches of the blank at both ends would be oversized from the lap reaching the end of its stroke and not being properly guided. I don't know if your barrel maker laps the blank or not or if he did, perhaps did not remove enough material to get back to a "good" bore diameter. These are some of the mistakes that can be made when making match barrels, but the supplier should know these risks very well and be taking care of what is important to you. So far I have bought several Shilen barrels and not had a problem with an oversized throat on any of them. In fact, the only problem so far is that one throat was undersized. Opposite problem... [/QUOTE]
Insert quotes…
Verification
Post reply
Forums
Rifles, Reloading, Optics, Equipment
Reloading
Is it possible NOT to get accuracy from A-max 162?
Top