I have three 380 auto pistols and have been having trouble getting decent accuracy out of them. I tried some Winchester 95gr. FMJ-FP ammo and it shot quite well. In an attempt to explain why the Winchester ammo shot well and all the other factory ammo and most of my reloads didn't I started pulling bullets to see what diameter they were.
Of the factory ammo, most were .355" diameter, some were .356" diameter and only the Winchester bullets measured .357" diameter. This test seems to indicate my three 380's prefer the larger diameter bullet for best accuracy.
Then I looked at my reloads. Of the many purchased bullets I have on hand for the 380 auto, most factory produced jacketed bullets measure .355" diameter. Most of the different plated bullets measure .356" and the hard cast bullets I had ordered are .356" diameter.
Knowing the Winchester bullets had measured .357" diameter and Graf & Sons listed the same Winchester bullets they have available as being .356" diameter, I ordered a (100) to see what they would measure. They measured .357". Great, so I loaded a couple of different loads using the Winchester bullets. Both loads shot quite well.
Then I ordered three different hard cast bullets in the styles I have been using, but in a .358" diameter so I could size them to whatever may work best. I preceded this order by using pin gauges to determine the bore size of my three 380's and made Cerrosafe castings of the bores to see what the groove diameter is.
I will start by saying I understand the rule of thumb says a Jacketed bullet usually preforms best when it fills the bore and cast bullets perform best at .001" over groove diameter. So when I measured the bore castings I found, The Walther PPK-S bore measured .3580", the Browning Black Label 380 measured .3592" and the Bersa Firestorm measured .3605". So what in the heck is going on here? I contacted all of the manufactures asking why their 380 bores look to be oversized. Both Browning and Bersa agreed that my measurements indicate the bores were not within specifications and Walther wanted the gun sent in for evaluation and only indicated it was within their specifications but was at the high limit for groove diameter. They would not replace the barrel. Browning and Bersa said they would replace the barrels.
I continued testing ammo and reloads in all three pistols using .357" and even .358" diameter bullets and accuracy can be had using bullets the fit these bores properly. Using these larger diameter bullets was possible due to the chambers being on the larger side also, so there was room for the brass to expand and release the bullet without excess pressure.
I sent the Browning in and they replace the barrel and slide. In the process they messed the gun up so bad that I had to return it. Browning replaced the gun with a new one. The bore in the replacement gun is oversized also. I either have to settle on reloads that will shoot well voiding my warranty or trade it off. Now I am afraid to send the Bersa in.
Why can't these manufacturers of 380 pistols produce barrels that are within their own specifications? Is there a reason they insist on making the bores oversized? It sure should not cost any more to manufacture a bore to proper specifications. I am unable to come up with any logical answer to this question. The Walther and the Browning are not cheap guns but for the cost the quality sucks.
Of the factory ammo, most were .355" diameter, some were .356" diameter and only the Winchester bullets measured .357" diameter. This test seems to indicate my three 380's prefer the larger diameter bullet for best accuracy.
Then I looked at my reloads. Of the many purchased bullets I have on hand for the 380 auto, most factory produced jacketed bullets measure .355" diameter. Most of the different plated bullets measure .356" and the hard cast bullets I had ordered are .356" diameter.
Knowing the Winchester bullets had measured .357" diameter and Graf & Sons listed the same Winchester bullets they have available as being .356" diameter, I ordered a (100) to see what they would measure. They measured .357". Great, so I loaded a couple of different loads using the Winchester bullets. Both loads shot quite well.
Then I ordered three different hard cast bullets in the styles I have been using, but in a .358" diameter so I could size them to whatever may work best. I preceded this order by using pin gauges to determine the bore size of my three 380's and made Cerrosafe castings of the bores to see what the groove diameter is.
I will start by saying I understand the rule of thumb says a Jacketed bullet usually preforms best when it fills the bore and cast bullets perform best at .001" over groove diameter. So when I measured the bore castings I found, The Walther PPK-S bore measured .3580", the Browning Black Label 380 measured .3592" and the Bersa Firestorm measured .3605". So what in the heck is going on here? I contacted all of the manufactures asking why their 380 bores look to be oversized. Both Browning and Bersa agreed that my measurements indicate the bores were not within specifications and Walther wanted the gun sent in for evaluation and only indicated it was within their specifications but was at the high limit for groove diameter. They would not replace the barrel. Browning and Bersa said they would replace the barrels.
I continued testing ammo and reloads in all three pistols using .357" and even .358" diameter bullets and accuracy can be had using bullets the fit these bores properly. Using these larger diameter bullets was possible due to the chambers being on the larger side also, so there was room for the brass to expand and release the bullet without excess pressure.
I sent the Browning in and they replace the barrel and slide. In the process they messed the gun up so bad that I had to return it. Browning replaced the gun with a new one. The bore in the replacement gun is oversized also. I either have to settle on reloads that will shoot well voiding my warranty or trade it off. Now I am afraid to send the Bersa in.
Why can't these manufacturers of 380 pistols produce barrels that are within their own specifications? Is there a reason they insist on making the bores oversized? It sure should not cost any more to manufacture a bore to proper specifications. I am unable to come up with any logical answer to this question. The Walther and the Browning are not cheap guns but for the cost the quality sucks.