Redirects issue and htaccess - .htaccess

Question

I am having a redirect issue. I have my htaccess setup to do the following...
1. Remove PHP extensions from URL
2. Add custom error pages
3. Force some 301 redirects
But there is a huge problem with the redirects...
If a user goes to ...
www.mysite.com/articles/jewelry/types.php
... then, based on the 2nd 301 redirect, they should be sent to ...
www.mysite.com/article/medieval-jewelry-types-and-functions/
... however, they are redirected to ...
www.mysite.com/article/medieval-jewelry/types
If they go to ...
www.mysite.com/articles/picks/A_1.php
... they should be redirected to...
www.mysite.com/article/picks-tools/
... but they get sent to ...
www.mysite.com/article/how-to-pick/
It looks like the redirect is changing PART of the url ... probably because of the .php extension (but that is just speculation - because I know very little about editing the htaccess file). Any ideas?
Below is most of my htaccess file, with some comments on what MIGHT be causing the issue. Any idea how to fix it?
# enable the rewrite engine
RewriteEngine On
# Set your root directory
RewriteBase /
# remove the .php extension
RewriteCond %{THE_REQUEST} ^GET\ (.*)\.php\ HTTP
RewriteRule (.*)\.php$ $1 [R=301]
# remove index and reference the directory
RewriteRule (.*)/index$ $1/ [R=301]
# remove trailing slash if not a directory
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_URI} /$
RewriteRule (.*)/ $1 [R=301]
# forward request to html file, **but don't redirect (bot friendly)**
RewriteCond %{REQUEST_FILENAME}.php -f
RewriteCond %{REQUEST_URI} !/$
RewriteRule (.*) $1\.php [L]
ErrorDocument 400 /400.php
ErrorDocument 401 /401.php
ErrorDocument 403 /403.php
ErrorDocument 404 /404.php
ErrorDocument 405 /405.php
ErrorDocument 408 /408.php
ErrorDocument 414 /414.php
ErrorDocument 500 /500.php
ErrorDocument 502 /502.php
ErrorDocument 504 /504.php
# example of redirects
Redirect 301 /articles/index.php /articles/
# it looks like the redirect below is conflicting with...
Redirect 301 /articles/jewelry/ /article/medieval-jewelry/
# ... this redirect.
Redirect 301 /articles/jewelry/types.php /article/medieval-jewelry-types-and-functions/
# And this redirect...
Redirect 301 /articles/picks/ /article/how-to-pick/
Redirect 301 /articles/picks/index.php /article/how-to-pick/
# ... is conflicting with this one...
Redirect 301 /articles/picks/A_1.php /article/picks-tools/

Answer 1

Problem seems to be wrong order of rules, incorrect regex and mixing of mod_rewrite rules with Redirect (mod_alias) rules. Try this:
ErrorDocument 400 /400.php
ErrorDocument 401 /401.php
ErrorDocument 403 /403.php
ErrorDocument 404 /404.php
ErrorDocument 405 /405.php
ErrorDocument 408 /408.php
ErrorDocument 414 /414.php
ErrorDocument 500 /500.php
ErrorDocument 502 /502.php
ErrorDocument 504 /504.php
# enable the rewrite engine
RewriteEngine On
# Set your root directory
RewriteBase /
# example of redirects
RewriteRule ^articles/index\.php$ /articles/ [L,NC,R=302]
# it looks like the redirect below is conflicting with...
RewriteRule ^articles/jewelry/?$ /article/medieval-jewelry/ [L,NC,R=302]
RewriteRule ^articles/jewelry/types\.php$ /article/medieval-jewelry-types-and-functions/ [L,NC,R=302]
RewriteRule ^articles/picks/?$ /article/how-to-pick/ [L,NC,R=302]
RewriteRule ^articles/picks/index\.php$ /article/how-to-pick/ [L,NC,R=302]
RewriteRule ^articles/picks/A_1\.php$ /article/picks-tools/ [L,NC,R=302]
# remove the .php extension
RewriteCond %{THE_REQUEST} ^GET\ (.*)\.php\ HTTP
RewriteRule (.*)\.php$ $1 [R=301]
# remove index and reference the directory
RewriteRule (.*)/index$ $1/ [R=301]
# remove trailing slash if not a directory
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_URI} /$
RewriteRule (.*)/ $1 [R=301]
# forward request to php file, **but don't redirect (bot friendly)**
RewriteCond %{REQUEST_FILENAME}.php -f
RewriteCond %{REQUEST_URI} !/$
RewriteRule (.*) $1\.php [L]