Taurus Firearm Forum banner

1 - 20 of 21 Posts

·
Registered
Joined
·
354 Posts
Discussion Starter #1
Bought a PT809 about 6 mos ago & never could group well with it at 10yd target distances. Getting good groups with a 9mm semi-auto is not really my forte, but this one was a little over the top. After suspecting an out-of-spec barrel bore, I roughly measured the groove diameter with calipers & it looked like it was out of spec but couldn't be sure until I slugged it.

I recently ran a lead slug through the barrel & came back with a measurement of 0.3562" dia, which is too sloppy for the .355 jacketed bullets that are spec'd for this caliber.

Looks like this firearm will be going back to CS as soon as I can contact them for return.

Anyone else ever run across this same problem with this firearm/caliber?
 

·
Registered
Joined
·
1,420 Posts
I did a quick measurement on my S&W M&P 9 and 809c bores. M&P .354 and 809c .3555. I also measured a UMC 115gr FMJ bullet at .354 and a Speer Lawman FMJ 124gr at .355. Anyway, my 809c barrel bore is .001-.0015 larger than the M&P bore.
 

·
Registered
Joined
·
354 Posts
Discussion Starter #3
Yeah, since posting this message, I've checked a few other 9mm bores, of different manufacturers, with a caliper, & they all seem larger than the bullets. Wonder if this is typical of this caliber. Doesn't make a lot of sense, but maybe that's the standard for this barrel.
 

·
Registered
Joined
·
9,171 Posts
Are you taking into account projectile expansion when fired? And a slightly larger bore may also aid in loading different bullet profiles.
 

·
Registered
Joined
·
1,420 Posts
It's hard to get an accurate measurement with a caliper in the bore. I did take a new Remington UMC 115gr bullet that measured .354 and stuck it in the 809c barrel from the crown end, and it went in almost to the shell casing lip, maybe .010-.015 short of the casing lip. The .355 wide 124gr Speer Lawman bullet was noticeably farther back from the shell casing lip, maybe .030-.040.
 

·
Registered
Joined
·
4,792 Posts
Sorry you are having accuracy issues with your 809. It sounds as if your barrel is out of spec. I'm sure that Taurus C/S will give you a new barrel. Please let us know how it turns out. Thanks for the post
 

·
Registered
Joined
·
1,420 Posts
Sorry you are having accuracy issues with your 809. It sounds as if your barrel is out of spec. I'm sure that Taurus C/S will give you a new barrel. Please let us know how it turns out. Thanks for the post
I'm not so sure his barrel is out of spec. What I measured on mine at .3555 puts it really close to his .3562. I'll bet there are thousands of 809's out there with similar readings.
 

·
Registered
Joined
·
354 Posts
Discussion Starter #8
If it's not out of spec then these barrels are bored with a sloppy tolerance. The main thing that caught my attention after the 1st time I fired my 809, with jacketed bullets, is that I could only see copper fouling on the lands of the rifling with the grooves barely being touched. When I compare that with other firearm barrels I have & I can see deep copper fouling in both places.

Some of you may be right about it not being out of spec, but I'm checking with Taurus CS just the same to see what they have to say.
 

·
Registered
Joined
·
1,543 Posts
I'm not so sure his barrel is out of spec. What I measured on mine at .3555 puts it really close to his .3562. I'll bet there are thousands of 809's out there with similar readings.
I'm not sure what the spec of this barrel should be but the numbers between the 2 of you guys could be in the calipers used/accuracy of each tool.
You may want to measure one of your jacketed rounds after firing into water and see how much expansion you are getting, I'm thinking you will come close to the same 0.356 numbers.
 

·
Registered
Joined
·
7,681 Posts
If you drive a well lubed soft lead .358 diameter bullet through the barrel and measure. It should give an accurate measurement of the bore diameter. .3562 is sloppy for a .355 diameter lead bullet and combo will surly lead the bore but jacketed bullets are often undersized for the bore but still shoot respectively decent groups. Accuracy depends on just how much undersized the bullet is to the bore. Give CS a call and ask them.
 

·
Registered
Joined
·
354 Posts
Discussion Starter #13
If you drive a well lubed soft lead .358 diameter bullet through the barrel and measure. It should give an accurate measurement of the bore diameter. .3562 is sloppy for a .355 diameter lead bullet and combo will surly lead the bore but jacketed bullets are often undersized for the bore but still shoot respectively decent groups. Accuracy depends on just how much undersized the bullet is to the bore. Give CS a call and ask them.
I did drive a soft lead plug through the 809 barrel & the .3562" is what I ended up with.

I haven't noticed a disparity between bore & bullet on other calibers like .357's for instance. Those bores are usually .357 & the jacketed bullets are the same. Lead bullets of that caliber are, on average, .358".

Like I mentioned, I have a Ruger SR9 that was sent to their CS for other things & they replaced the barrel. Although I have not fired since it came back, It too appears to be out of spec. I plan on running a lead slug through it in the next day or two. Right now, with calipers, it measures similar to what the 809 did with the calipers.
 

·
Registered
Joined
·
36,326 Posts
AHHHH?
Didn't Ranch Dog quite some time back report that all the taurus 9 MM had a.3565 bore??
I think so?
this was in regards to a leading issue I believe?
and for those that aren't familiar with MR. Dog he built and designed molds for cast projectiles and did quite a bit of research.
maybe I am wrong as basically I care nothing about lead projectiles.
 

·
Registered
Joined
·
354 Posts
Discussion Starter #16 (Edited)
....Didn't Ranch Dog quite some time back report that all the taurus 9 MM had a.3565 bore??....
Didn't know about that report but, if true, why would Taurus rifle their 9mm barrels to make them larger than the standard diameter jacketed bullets that are available?
 

·
Registered
Joined
·
354 Posts
Discussion Starter #17
I found this pic online which represents exactly what a .355 wide Speer Lawman 124gr bullet looks like in the end of my 809c barrel
The article with this link makes the case that the 'groove' diameter should be the same as the 'standard' copper jacket diameter. The 'lands' diameter (which is actually the bore diameter) then engages the jacket to engrave it for a rotational spin.
 

·
Registered
Joined
·
354 Posts
Discussion Starter #18
I phoned Taurus about 9 am, my local time, & the wait times were long, being Monday & all, so I opted to contact them another day.

What I did do is run a lead slug through the barrel of my Ruger SR9, which I believed to be over sized too after checking the muzzle groove with a caliper. The lead slug micrometer measurement came in slightly higher than the caliper measurement, at 0.3564"...amazingly similar to the 809.

I thought maybe Ruger CS might be easier to contact today so I called them to see what they had to say about this dimension. The CS person I spoke to checked with the technician on the floor & came back & said that "yes" that was 'normal'.

I tried to get more detailed information such as where in the tolerance zone did that measurement lie & he said the production people were too busy today for that kind of information.

Sooo, maybe the 809 is correct too. Just doesn't add up, to me, that a groove diameter in a bore would be larger than the bullet diameter that its intended for.

I still plan on checking with Taurus later in the week during non-peak times. it'll be interesting to hear what they have to say about it.
 
  • Like
Reactions: RalphG2

·
Registered
Joined
·
1,667 Posts
I'm spent my fair share of time slugging Taurus pistols and haven't found one on the SAAMI spec yet. The correct tool to use is a pure lead slug with a hole through the longitudinal axis, like a lead string sinker, so that the "crush" can be relieved. A solid slug pushed through the barrel will not give a true reading as the elasticity of lead will cause it to expand as soon as it is free of the restriction. A micrometer of at least .XXX5" resolution should be used to measure the slug. Every 380 Auto and 9mm Luger I've measured, including the 809, has had a groove of .357" to .358".

I also take chamber casts along with the barrel slug. The Cerrosafe with about one inch of leade into the barrel allows me to compare the slug as well. I have always found the chamber to be on spec but the bore/groove over so it is intentional on Taurus' part. My guess is that it allows for positive feed, any variation of bullet should chamber and at the shot pressure is dumped pretty quick.

I've done the same work with the Taurus revolvers and the Rossi rifles. These are right on spec; chambers, bore, and groove. This is another indicator to me that the pistols intentionally have over diameter barrels. When I made the Taurus purchases for my cast bullet design work, I returned the first one measured as out of spec and it was returned as being on spec. This trend extends to the 25 Auto, 32 Auto 380 Auto, and 45 Auto. I've never looked at the 40 S&W as my work did not call for it.

For a factory ammo shooter or jacketed bullet reloader, there really is no downside other than the velocity will never be as published when corrected for barrel length and temperature. The pressure is dropping too rapidly with the over-grooved barrel. For a cast bullet shooter, it can be a bit of a nightmare to figure out. I tried marketing cast bullet molds tailored to the product line but there was just not enough interest to make it worth the trouble. Honestly, owners just find it hard to believe that the pistols are intentionally over bore and groove.

Here is what I've found with the 380 auto and 9mm Luger barrels, I believe they use a common stock.





To make my point, I've pushed a jacket bullet through these barrels a number of times. It doesn't take much effort.

 

·
Registered
Joined
·
354 Posts
Discussion Starter #20
Appreciate the very informative information Ranch Dog. That puts my mind at ease because I was thinking I was going to have to send my pistol back to Taurus CS. That is until I found the same phenomena on my Ruger SR9 pistol. Ruger CS told me that it was 'normal', so I guess your research results don't only apply to Taurus.

Thanks again.

PTD
 
1 - 20 of 21 Posts
Top