Barrel Life question

[buzz]

Anyone know the average barrel life for a Thompson?

 

I mean how many rounds are needed to shoot out the barrel, for the original Colt or USGI barrels.

 

Also, what usually wears out first? Throat or rifling?

 

 

 

 

[MG08]

Barrels do not like heat. so How you shoot it makes a huge difference. But realistically unless your name is Mike Dillon, you will probably never wear out a barrel. Based on a postie I have, barrel life is at least 20,000 rds. Of course, I have no idea how many rounds it had when it was cut up. I am sure others will chime in too......

[bug]

What MG08 said regarding how the gun is used.

 

My Savage was 57 years old when I got it and I believe the barrel to be original. I have no idea what went through it in those years but it was a PD gun so use could have been light. Since 1997 I've put around 5K brass cased and 12 to15K Wolf steel cased rounds through it. loooonnngg bursts and mag/drum dumps are limited but they are necessary. Moderation is the key word here. The bore looks fine to me. Accuracy OK with no keyholing. I have no way of evaluating the throat condition...,

 

Bob D

[reconbob]

My rule of thumb for the expected life of a barrel is 150,000 - 200,000 rounds. This is based on the

feedback I get from rental ranges for whom I have supplied many guns. I have heard of barrels lasting

250,000 rounds but I think that is excessive.

My opinion is that unjacketed lead bullets will wear a barrel faster than ball because girt, sand,

metal filings, etc. even if almost dust like will stick to the lube or imbed in the soft lead and scrape

the bore. In a similar way back in the early days of the Springfield they had brass cleaning rods figuring the

brass was softer than the steel and so would not harm the rifling. But grit and debris imbedded in

the rods, damaged the bore, and the brass rods were discontinued. In the 1960's they developed a

duplex round for the M-14 which was two steel projectiles loaded one on top of the other so you would

get 2 shots with one trigger pull. These bullets were plated - not jacketed, steel and there was no

ill effect on barrel life. Later on in a effort to make the M-14 controllable in full auto they constructed

"low recoil" 7.62 NATO rounds using one of the lightweight steel duplex bullets. OK, I am adrift...

The thing that usually signals the end of the life of a barrel is when the gun starts to short-recoil due

to a bore worn so much there is no longer a good gas seal. This was discussed at length recently regarding

a WH with a shot-out barrel. People do not target shoot with Thompsons. They plink and have fun so a

deterioration in accuracy is not noticed.

Certainly the hotter the barrel gets, the faster it will wear. However, for this type of destructive erosion

you have to be approaching red hot where oxygen will chemically erode the steel as opposed to wear

from friction. Now, you can get red hot real fast with high powered automatic weapons. One 20 round

mag thru a BAR or an M16 will have the flash hider glowing red and the barrel is not far behind. Fortunately

you are slowed down by having to change mags. There are numerous accounts of WW2 and Korea

extreme-use episodes where the wood stocks of Garands and BARs actually started to char. But if its

life or death you are not a gun collector and you keep shooting.

I never did a drum dump with a Thompson. I know many f you have. If you have, did you do it at

dusk or dark and was the barrel or comp red hot? (I know someone will try this in the name of research.)

Please have digital camera at hand...

 

Bob

Edited September 23, 2014 by reconbob

[shadycon]

Run 4 20rd mags thru an M16 on full auto as fast as you can and see what happens! After that I couldn't hit a man size target at 50yds.GK

By the way I was doing as told by the drill sgt!

[mnshooter]

In the interest of science and this thread, I'm taking the drums to the range at the earliest opportunity.

 

Have to wonder about the lead bullet wear issue.

A round nose profile would have almost no exposed lead in contact with the bore, and the cylindrical body would be protected inside the case. Assuming the bullets were kept clean until loading, and not allowed to set out exposed where they could accumulate any dust or debris, there should be no reason for barrel lapping effect.

A SWC style bullet with a full diameter exposed shoulder would have the potential you described, but probably not too many of this pattern are used in Thompsons.

I have run this type (H&G 68 -200gr SWC) through a 21, 28, and M1, and contrary to what was expected, had 100% function with box mags and drums. However, these were all copper plated versions, so can not be sure the unplated lead type would do the same.

Another benefit to the plated bullets: the comp stays beautifully clean.

Edited September 23, 2014 by mnshooter