BLOWBACK Fouling with new [to me] barrel....UPDATE.

[offhand35]

I just got an older t/c  45 Colt bull barrel that turns out to be chambered for 45colt/.410 shotshell, all rifled, no choke, with older style sights, but with the 2 pc latch.
I got to the range with it this last Sat., and shot 4 different loads with it, none of them apporaching max for T/C, Ruger loads.   When I got back,  I discovered that the entire inside of my Contender handgun frame is covered with fouling, and the breech and lug of this barrel are covered as well.  There is no fouling above the upper edge of the breech, it all seems to be directed downward and sideways.
Should I be concerned that this demonstrates a head space problem with this barrel?   This is NOT exhibited in any of my other handgun barrels,  10" 38spl Oct,  10" 41mag bull,  11" custom 40s+w!

My other concern is that continued use of this bbl will introduce so much fouling to the frame that after a short while, it will start having problems......

I emailed the seller [not Ed K.] re: this to see about an exchange......that was just little while ago, waiting for a response from him.

[SHOOTALL]

your loads might not be strong enough to expand the case and seal the chamber .

[rickt300]

It could be that your loads are not building enough pressure for the cases to obturate.  Are you using a slow powder like IMR 4227? What do the cases look like?

[WolfTrap]

Stop using the barrel!
1. TC may have used a dull reamer that left a oblong chamber.
2. The TC barrel could have a hairline crack in which you risk vision or death!
3. The likelihood of getting satisfaction from previous owner may not present itself?
4. The probability... the owner may have encounter the same danger?
WT   

[offhand35]

Thanks for your quick replies.  I have not shot 45Colt in a very long time, and never before in a Contender.  SOME of the loads I was shooting were indeed leftover low power loads for a revolver I no longer have.  When shooting that, I had no concern about the fouling.

I  did not sort cases as they were fired as I did not know I was looking for this.  I still have some of each load left, and will certainly look at the cases next time.

However, in looking over the brass, it is apparent that some cases did seal properly, as they are clean and some other cases are not clean.  THOSE are probably the loads that caused the fouling.

These are the loads that you asked about.

8.5 gr HERCO  w/ 250gr RNFP  and 255gr LSWC
9.0 gr HERCO  w/ 250gr RNFP and 255gr LSWC

17.0 gr AAC #9 w/ 255gr LSWC

I did not clock any of these as I was looking to shoot off the low power loads, get a general idea for sighting in, and looking for accuracy potential within a time  limit at the range.

The 8.5gr HERCO loads were definately lighter as I fired them, and they are the likely source of the fouling.  Even the 9.0gr HERCO loads felt beefier,   but still did not approach the apparent power of the AAC #9.

I am now out of the AAC #9 , and am looking to use up a couple #'s of IMR 4227 that I have.  I will plan to start at the higher edge with the 4227, and observe for case fouling.
The HERCO loads can go to 9.5 grains.  The 9.0gr loads were pretty accurate for me, and the 9.5's may do better.

Thanks, I'm glad I posted here. I was ready to blame the barrel, but maybe the character of the lighter 45Colt loads are  be the culprit.


NOTE:
I see now before completing the post, that WofTrap  actually agrees with my original concerns! 
Maybe a call to T/C and possibly sending them the bbl will be in order, just to be sure.

[Keith L]

TC can tell you if the barrel is safe or not, but what they can't do is turn a .45/410 barrel into a .45 barrel.  While there are rare sightings of people who are happy shooting .45 out of these combo barrels most who want to truly hit what they aim at are not very satisfied.  The seller, if he didn't disclose what the barrel truly was, should be given a chance to stand behind his goods.

[MePlat]

The bullet leaves the case then wobbles down the barrel with gaps between the bullet and chamber walls so pressure is dropped drastically.  Hench blowback because of the case not sealing well enough to prevent blowback..  One will get the same effect with a derringer chambered for the 45 Colt and 410.  I KNOW.
get use to it or go up on the pressure with a slower powder to keep the pressure curve that you have working longer to maybe allieviate some of the problem.. "Some" being the "key word."

[Ladobe]

If I wanted a 45 barrel, I  would be more concerned with the seller not telling you it was a combo barrel myself.   Like others have suggested re the low pressure loads, I doubt there is anything wrong with that barrel other than it being a combo that never will be an accurate 45 shooter for you because of the chamber.

[SHOOTALL]

i had such a bbl. it was clearly marked as such . if yours is not it may be a copnverted bbl.
If in fact  it was converted and a shabby job done you would have recourse .

[Hopalong7]

   TC never made a barrel chambered for .45Colt/.410 with no choke!!!  When you say no choke and full rifled I assume you mean rifled right up to the muzzle with no threads for the choke to screw.  On the bull barrel the threads will be on the inside.  TC did make for about 10 years(1974-1985 give or take) a barrel marked ".45Colt" that was chambered to allow the use of .45colt brass loaded with shot capsules.  These barrels were made in both octagon and bull versions, BUT, both versions had chokes.  Your barrel sounds to me to have been modified.
   If the old noggin' is functioning at all, 8.5gr Herco should be enough to seal off a normal chamber behind a 250gr bullet.  Alliant show a 9.5gr dose of Herco and a 250gr lead bullet doing 1021fps.  I wouldn't think a full grain drop would be over 200fps or so and would put you pretty close to standard factory loads for .45Colt.
   I would definately talk to seller and/or TC.  Good Luck with it.  Walt 
   
   

[MePlat]

First lets look at the length of chamber and then use common sense.  It isn't that the case may seal at the first few 10 tousandth of a second but that as soon as the bullet starts down the long chamber gasses then escape around the bullet hence pressure loss and then gas blowby.
One could possible blow the barrel with a caseful of bullseye but as soon as the barrel let go no more pressure so even though one could seal the case to the chamber with a load of Herco, Unique, bullseye, powerpistol, hs-6, titegroup, etc. etc. or any other powder as soon as the gasses escape around the bullet guess what will happen???    Gas blowby.  Can it be lessened?  Yes but not by much.  I would try 2400 myself but that is just me.  And I would try 18.5 with a 255 Keith or 17.5 with a RCBS 270 SAA bullet.

[Hopalong7]

   I've not had any of this "gas blow by" fouling problem in any of my .45colt/.410 barrels and I've had at least 5 or 6 over the past 20 years.  Granted the .45 bullet has a good little jump before it engages the rifling and they are certainly not known for being moa shooters, but I've not heard of this fouling blowing back into the action before.  GOOD SHOOTIN',  Walt 

[SHOOTALL]

i had 2 one like the one in ? and one with a screw in choke . No blow by problems . it would seem the case would expand before the bullet left . The first pressure peak would be what makes the bullet start to move . At that time the soft case should have expanded to fill the chamber if it were going to.

[offhand35]

Thanks for all your replies so far,  I find this all very informative!  The seller did reply to my email, and he is one straight up guy!

This was his reply:  "No idea this would happen, I don't any of the bbl's.  Would you be willing to  give Thompson a call?  If they can help out, go that route, if not I'll refund your money or give you another bbl.  Thompson are pretty good  bunch of people to deal with.  Let me know what happens, we'll get 'er corrected somehow."


At this point, I plan to send the barrel to T/C tomorrow for inspection.   I think, from what I have been seeing here, that we may find that the barrel has been modified, as there is a whole LOT of unrifled space in front of where the 45 Colt chamber should end, with a 2nd step visible roughly where a  3" .410 shell would end.  A 3" .410 shell drops right in and the action closes with no resisitance.  I hope that T/C can find an explanation for the problem!

[rickt300]

Another thought, how old is your brass?  I have a Handi rifle in 44 magnum and some brass I have been using for more than 15 years. This brass is work formed into some really tough stuff.  Even with full loads a little gas works it's way past the brass and dirties it up, some does go back into the action a bit also.  Add to this the long throat the barrel has and I think we are experiencing the same thing but with different guns.

[offhand35]

Well, I have 300 pcs of Winchester 45 Colt brass that are about 10 years old, but was no more than fired 2x  before I started with this Contender bbl.  The chamber is definately over sized in length.  Maybe somone bored it to 454 or to .410 shotshell prior to the seller obtaining is.   Regardless, I was looking for a properly chambered 45 Colt barrel.
I did send it to T/C for them to evaluate and advise regarding it.   IF they say there is nothing incorrect with this bbl, [and I really don't believe they will]  it does  shoots ok, as far as starting loads go, but I am not happy with the fouling, and plan to return it and go looking for another with a proper chamber.

[offhand35]

Well, here is the update regarding this barrel:

I wrote to the seller with T/C's response, his reply follows.

    I received the 45Colt bbl that I bought from you back from T/C today. It
    included a note from customer service that reads:

    "Barrel has been altered. It should of been just a 45Colt. Has been
    rechambered to a 410. Not covered under warranty."

    I have since purchased elswhere a NIB NOS barrel that is strictly 45Colt
    chambered only.
    I wish to return this to you for purchase price  only. All the
    shipping costs are typically borne by me the purchaser, and I have no
    problem with that. If the problem were simply the chambering, I would
    consider simply re-selling it myself, but because of the probable
    headspace problem on my frame, indicated by the heavy blowback fouling,
    I would hesitate to sell it to anyone.

    T/C went no further than to state that the barrel had been rechambered,
    and did not attempt to address any headspace problem, as the
    rechambering was not their doing.

    I will include the note from T/C with the bbl.

    Thanks

His reply:

Afternoon David;
 
  No problem, something that could not be foreseen, I will pay your return cost also. 
  Semper Fi