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Discussion Starter · #1 ·
Second post.
I have a couple of 75B SAs, 40 S&W. I installed a Cajun bushing on one of them. With the new tighter bushing, the last round in the mag is not ejecting properly and deforms the case mouth. I put the barrel from the 2nd gun into the first and it still mangles the case. Only the last round from the mag. Tried different loads with several bullet types and same result. Tried different mags, same thing. Substituted a different slide stop, same.

Put the original bushing back in and problem goes away.
Any ideas?
 

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The last round in the mag typically does not eject as strong or far as the ones before it. Slide rides better on a round piece of brass as opposed to the slide stop riding up on the rail from follower pressure.

So with the new bushing things are a little tight or you could be experiencing some barrel binding and your last in the mag rounds are just making it to the point where the slide is coming forward and crushing them.

Make sure the gun is unlocking/ locking without much force. If so then perhaps some higher pressure rounds and or a lighter recoil spring or a lighter hammer spring .Although a lighter hammer spring can lead to other issues . As the bushing wears in a bit things will loosen up.

Also I installed a new bushing in a 75 in 9mm and you need to make sure that you did not ding up the rear of the barrel hood area or breach face on the slide as you get the barrel into the slide -its a tight fit as you know.
It is possible that you may have even dinging the extractor , unlikely but possible . Any of this may cause the gun to unlock hard.

Kirk
 

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"Put the original bushing back in and problem goes away. Any ideas?"

Yea...

Leave the original bushing in and take back that Cajun one !!

What's to think about...!? :rolleyes:
 

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Following this too. The first thing I thought of was some barrel binding as well - does the rear 1/3 of your barrel slide freely into the bushing? Just throwing it out there...
 

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Discussion Starter · #6 ·
Tested this morning by installing a 9mm barrel and mag. Last round was barely out of the chamber without fully ejecting. No denting. All the others ejected and landed approx. 8 feet away. I made sure there was no crud build up on bolt face or under the extractor.

Next test will be a more powerful load or a lighter recoil spring.
 

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I have ran into this on several guns. There are 2 causes, first your extractor tension or fit is not very good. Depending on the age of the gun you might need to replace the extractor spring or fit the extractor for a little more grip on the rim. Why does it do it on the last round? Because the last round does not have a solid cartridge case to bounce the empty shell off of. Why is it doing it with the new tighter bushing? Because the CZ barrel has no taper and if anything may, depending on the year of manufacture, get larger towards the chamber end of the barrel. The new bushing is accordingly tight, the instruction say that some fitting may be necessary and in your case the extra drag on the barrel by the new bushing is causing your first issue to show up because of the reduced slide speed. Remove and clean the crud from behind the extractor, install a new extractor spring, polish the barrel between the 2 lines pictured below and try to remove a small amount of metal between the 2 lines. Mounting the barrel into a padded vise by the chamber end and using some 1" strips of 320 grit paper works well for this. Measure the diameter of the barrel and then shoe shining the strips on the barrel remaining between the 2 lines remove several thousands on top and bottom. Removing a small amount of metal here will free up the barrel and return the slide speed to normal but also let the gun lock up tight when in full battery and will still let the 10X bushing do its job.

 

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Be sure to look at the witness marks on the front of the barrel, usually about 1/2" behind the crown. You don't want to remove any metal on the barrel for the first half inch. This will maintain the tight lock up when the slide is in full battery. As the slide moves rearward and the barrel starts to tip you can make a mark and remove a few thousands behind this, this will free the slide up and will still work just as well with the stock bushing should you decide at some point to reinstall it. I have had to do this on several guns to get the slide speed back after installing the new bushing. The added benefit of the tighter groups are well worth the extra time spent freeing up the slide.
 

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Discussion Starter · #10 ·
Took your advice. Carefully chucked the barrel in the drill press padded with tape. Spun and sanded approx. .002" off the diameter. Replaced extractor spring. New one is more than twice the length of the worn original.
Problem solved. Thank you.
 
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