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380 Auto Oversized Bores

1K views 11 replies 7 participants last post by  UncleFudd 
#1 ·
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.
 
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#3 ·
I am truly surprised there aren't more shooters out there having a problem getting expected accuracy out of their 380's. Perhaps I expect more or I am not ready to except what some of these 380's have to give.

When the manufacturers ignore their own specifications in order to fill the market demand for a 380 auto, all they succeed in doing is to flood the market with a substandard product, convincing the buyers their product is not what they expected it to be. They usually won't buy that product again.

It is what it is and I for one don't like it.
 
#4 ·
Sorry.. can't help you.. I only have sig 380's in daily use.. and they are dead nutz on.

I have a keltec .380 as well, but, surprisingly enough, for a cheap gun.. the barrel is correct. They cheaped out on frame, but went good steel on the slide and barrel.
 
#6 · (Edited)
rcairflr,

If you reread my original post you will see that I had the Winchester WB 95 grain FMJ-FP shooting good groups. That bullet measured .357" diameter. I also indicated because the bores all measured over sized and out of specification with the manufacturers specifications I used oversized cast bullets and was able to shoot good groups with a number of reloaded loads.

What I didn't mention in my original post is that all my load testing is done at fifty feet. Now before you go off on me, I need to explain the reason I shoot at fifty feet. If I were to conduct all my testing at no more than twenty one feet, the groups would all be quite small and difficult to read when looking for load variations, shooter variations such as grip changes or sighting problems and even trigger control problems. Tiny groups look great but say little else. So, I shoot at fifty feet, I can shoot at fifty feet and accurately when all is right or made right for the gun and ammo. Good accuracy loads fired at fifty feet will be great loads at the belly gun ranges and a person can't ask for much more.

I like many shooters can have an occasional bad day but to answer your question, "No, the poor groups were not caused by the shooter." They were caused by both factory ammo and reloads that use standard sized bullets and they will not shoot with decent accuracy in oversized bores. These guns will shoot nice little groups at fifteen to twenty one feet and if the shooter is a pinker or a bucket shooter, then the shooter will be very pleased to own any of my 380's.

I guess I am probably the most unlucky person when it comes to getting a pistol that has all good parts including a barrel with the proper sized bore. I will have to decide if I keep these pistols that have a sad lack of manufacturers quality control or be content to use mostly reloads with oversized bullets and/or trade them off hoping the new owner will be a person that is content to shoot small groups at fifteen to twenty one feet and tiny groups no matter what ammo they use. These people will be happy and they are the type of shooter that the belly gun manufacturers are trying to serve.

By the way, Browning agreed my Black Label 380 was not according to their specifications and replaced it with a new one.
 
#7 ·
rcairflr,

What I didn't mention in my original post is that all my load testing is done at fifty feet. Now before you go off on me, I need to explain the reason I shoot at fifty feet. If I were to conduct all my testing at no more than twenty one feet, the groups would all be quite small and difficult to read when looking for load variations, shooter variations such as grip changes or sighting problems and even trigger control problems.
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Why would I go off on you? I do the majority of my pistol shooting at 75 feet. I shoot for marksmanship and sometimes at 150 feet anytime I go out to the cabin. Shooting at 150 feet is very challenging. I hardly ever shoot 21 feet because it is too easy and would just be 1 raged hole.
 
#8 ·
rcairflr

Sorry. I was over reacting to your question that maybe it could have been the shooter.

It is good to hear from someone that can appreciate the difficulty of shooting at distance. Example being the 2-1/2" to 3-1/2" barreled 380's.

I am one that loves shooting and reloading. That said, a lot of load testing in a number of guns does provide me with a lot of shooting and reloading.

I have always been a logical thinking person and very analytical and investigative type also. This is mostly why I spend so much time testing things that most would not be interested in.

It is also why I tend to push the manufacturers pretty hard when they get quite relaxed with their quality control. It has never made sense to me for a manufacturer to set specifications to be met where quality is desired, only to use inspection frequency that allows far too many out of spec parts to slip through. They must think most shooters out there will not know the difference.
 
#11 ·
I guess it all depends on expectations. I have two .380's, and have previously owned several others. I've never had what I would consider accuracy problems.

In my life I have gone from shooting at 25 yards because that was the shortest available range, to shooting at 15 yards because the range I shot at for many years gradually pulled the target frames in as more and more people were interested in shooting at big targets at short ranges. They ended up leaving only a couple of 25 yard positions on the pistol range, and mostly those were always full of kids with .22 rifles. So I was sort of forced down to 15 yards. No matter, I just scaled my targets down proportionally.

I don't expect to be able to shoot my .380's as well as my larger guns, which are 6" S&W revolvers and target grade 1911's. But I figure if I can shoot the .380's as well at 10 yards as I can my target guns at 15 yards, I'm good with that.

I've never had truly poor results with factory ammo, but mostly I shoot a lead bullet reload with W231. This was one of those rare times when I tried just one reload and since it shot better than factory and met my expectations so I just stuck with it. The .380 is a secondary caliber for me anyway. When I get a chance I'll slug my bores. I'd bet the Taurus is over sized as I know the Taurus 9mm's run large.

This is a Taurus PT638 with 50 rounds of Winchester White Box at 10 yards. The target is a 4" bullseye. My reloads shoot a bit better. I'm satisfied with the results for the gun all things considered. Granted I'm not the greatest pistol shot but that's as good as I can do at 15 yards with my best guns.

Gun Firearm Airsoft gun Trigger Revolver
 
#12 ·
Makes me wonder if this is a tooling AND QC problem.
Perhaps their tooling had become worn with use and after X number of barrels the holes grew by one or two thousands. Then, because the QC guy had inspected the barrels as the first 100 or so barrels came off of the line, he took for granted that ALL the remaining barrels from that set were good to go.
Could be a number of things but it remains as you said, we expect the specs (set by the company) would be accurate for ALL barrels regardless of where they fall in the machining process.

I only have one Browning, an old BDA, a couple of Colts, two Makarovs and Beretta 86 and a Ruger LCP and am going to mic them all to see if there is any difference.
Thanks for the heads-up and I will get back as soon as I can. I'm out of pocket for a few days for cancer treatment but should be able to post again by thur or Fri.
Should be fun and interesting.

UF
 
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