Normal throat erosion?

[hunter686]

Just taken delivery of a 6.5 Wildcat. Since getting the rifle i have out 181 rounds down the barrel. I had it throated with 0.139 free bore (Coal 2.939) to load the 140 ELD-M bullets long. I just checked the throat as I'm about to start a seating depth test.
I have done two methods of checking the throat.
1: I took the firing pin out and loaded the round long seating it 5tho at a time until the bolt dropped freely. The second method was load long and chamber the round. Both were done with the same bullet used to set the freebore at the smiths. They both gave me reading of 2.989.

Is this normal? The barrel never got hot.. barley even warm. It was mostly shoot and check as was learning the load for the rifle. Barrel is a Bartlein heavy palma shooting 45.5 of grains of H4350, temp when shooting was around 15 Oc (65F)

 

[Cowtownup]

I'm not sure if this will help but I'll add it anyhow. I've got a Bartlein 1.25" straight bull barrel chambered in 284 Winchester. It has grown about .017" in just over 1000 rounds. I'm curious about how much throat erosion people are seeing as well... Good luck..

 

[Zero333]

Make sure chamber is clean.

50 thou erosion in 200 rounds is phenomenal, in a bad way.

Did you clean the chamber and barrel when you received the rifle before you took your initial measurement ?

 

[hunter686]

Make sure chamber is clean.

50 thou erosion in 200 rounds is phenomenal, in a bad way.

Did you clean the chamber and barrel when you received the rifle before you took your initial measurement ?

Measurement was taken by my smith so that the lands just touched the dummy round i sent him. By my calculations i wanted a free bore of 0.140 (never divulged this exact number) to my smith so when he got back to me saying 0.139 left the round snug against the lands i knew he was bang on. He's one o the top smiths in the country so I trust him 100%

 

[hunter686]

I'm not sure if this will help but I'll add it anyhow. I've got a Bartlein 1.25" straight bull barrel chambered in 284 Winchester. It has grown about .017" in just over 1000 rounds. I'm curious about how much throat erosion people are seeing as well... Good luck..

This is more what i was expecting. I'm hoping i have made a mistake.. but i can't see how

 

[Dshooter]

Something is fishy for sure. My 300 Ultra with nothing but heavy doses of pills and powder only grew around .012 the first 200 rds. And that thing eats barrels

 

[Willie]

It happens fairly often on a newly cut chamber, that there is a slight burr, here and there, that gives a false reading on lands. On a new barrel, I'll go ahead with break-in, just to get everything smoothed up. Then another good cleaning, borescope to be sure all is well and then check the CBTO with each bullet type or weight that I might use in that rifle and record it.

I, too run some hotrod 6.5s and I re-measure every 200 Rds to monitor lands movement on each one. My best guess would be that the initial measurement was off or perhaps measurements by two people, with different methods or comparators. The only measurements that count are the ones I take with my tools, after break-in and at the intervals of round count determined for different cartridges.

 

[expiper]

I usually break in a new bbl (at least 10 rds) and then measure the FB ,,,I save that bullet and use it as the round count grows to take my measurements,,,,Roger

 

[hunter686]

I'v messaged my smith to see what he says. He's used a DK neck micrometer reamer to set the freebore.
Regardless of measurement right or wrong I can now chamber a round at 2.989 now. 0.009 Over my max mag length of 2.980.

Going to have to call her Evel Knievel. Cos this mofo is going to have to get used to a good jump

 

[M995]

[QUOTE="hunter686, post:
1: I took the firing pin out and loaded the round long seating it 5tho at a time until the bolt dropped freely. The second method was load long and chamber the round. Both were done with the same bullet used to set the freebore at the smiths. They both gave me reading of 2.989.
[/QUOTE]
These 2 measurements should never be the same. Long loading & hard jam is .020" + longer depending on seating pressure. The touch can be hard to determine if the bullet isn't perfectly concentric with the case ( it will give false feel when the bullets drags the freebore wall ). You never mentioned the ejector system

 

[hunter686]

[QUOTE="hunter686, post:
1: I took the firing pin out and loaded the round long seating it 5tho at a time until the bolt dropped freely. The second method was load long and chamber the round. Both were done with the same bullet used to set the freebore at the smiths. They both gave me reading of 2.989.

These 2 measurements should never be the same. Long loading & hard jam is .020" + longer depending on seating pressure. The touch can be hard to determine if the bullet isn't perfectly concentric with the case ( it will give false feel when the bullets drags the freebore wall ). You never mentioned the ejector system[/QUOTE]

I sized the case 0.001 under so there was barley and neck tension. Also put some imp sizing wax on the bullet to stop it getting stuckin the lands. I did this 3 or 4 times and the measurement came out the same to the thou. You can see the rub marks from the lands on the agive of the bullet.

As for the ejector i left that In place; As the free fall of the bolt handle was enough to gauge weather the round had made contact with the lands or not.
I find it's too much of a coincidence that both tests yielded the same measurement with multiply trys of each

 

[dkhunt14]

I agree with M995 in that both those measurements shouldn't be the same. With even .001 tension and shutting the bolt on a case with a long loaded BULLET, it should be at least.015 in the lands. Some thing is wrong with your measuring on one or the other. Try taking the ejector out and repeat. Make sure to size the neck nefore doing it so bullet has tension. Matt

 

[Slim13]

Just circling back as I’ve spoke to a few others hat have had similar experiences in their 260’s. .05 is on the high end of erosion but .03-.04 is pretty typical after 1000 reds with moderate loads. By the end of 2018 I’ll need a new barrel it seems. I’m probably going to a 6.5x47

 

[ShootDots]

I just finished shooting a match with a brand new Krieger barrel. I was shooting a 260A.I. One hundred rounds later the throat moved exactly 3 thousandths. That is normal for a "High Pressure / High Intensity" round. The reason this barrel is new is because my last barrel went south at only 1050 rounds! I NEVER had that happen with a 260A.I. before! Most get in the vicinity of 1700 rounds! My borescope was telling me I had 7 inches of firecracking, the lands were splitting and the edges of the lands were broken off! The firecracking was so bad in the grooves it literally looked like alligator hide for 7 inches! ALL THIS ON 1050 rounds! WHY? I don't exactly know. But powder (H4350), running it all summer long in Arizona and the possibility of the barrel steel maybe not being up to par???? I don't have the answer. I have seen barrels that SHOULD be burned out at 17-1800 rounds go well over 2000>>>approaching 2500! I had a Dasher barrel shooting VV N540 last only 1500 rounds! However, your barrel is W-A-Y on the unusual side! One thing I have learned in this game, the longer I stay in this game, the more unusual things I see and learn of!

 

[MagnumManiac]

I just finished shooting a match with a brand new Krieger barrel. I was shooting a 260A.I. One hundred rounds later the throat moved exactly 3 thousandths. That is normal for a "High Pressure / High Intensity" round. The reason this barrel is new is because my last barrel went south at only 1050 rounds! I NEVER had that happen with a 260A.I. before! Most get in the vicinity of 1700 rounds! My borescope was telling me I had 7 inches of firecracking, the lands were splitting and the edges of the lands were broken off! The firecracking was so bad in the grooves it literally looked like alligator hide for 7 inches! ALL THIS ON 1050 rounds! WHY? I don't exactly know. But powder (H4350), running it all summer long in Arizona and the possibility of the barrel steel maybe not being up to par???? I don't have the answer. I have seen barrels that SHOULD be burned out at 17-1800 rounds go well over 2000>>>approaching 2500! I had a Dasher barrel shooting VV N540 last only 1500 rounds! However, your barrel is W-A-Y on the unusual side! One thing I have learned in this game, the longer I stay in this game, the more unusual things I see and learn of!

The reason you had such early barrel life is due to the powder you were using.

I run 300WM barrels and I kept a record of how many rounds I fired in a barrel using only H1000 powder and my other barrel running RE25.
The single base powder barrel had gone south @ 1236 rounds, from 1/4MoA to 1MoA in a 250 round string. The fire cracking was a good 10” and the throat was LONG.
The double base powder barrel has lost 1/10MoA and has 2028 bullets down it so far, the damage inside the barrel is their, but not even half that of the other barrel.
Single base powders burn far hotter than double base powders, which is why it fire cracks earlier.

Another interesting note, I have gone to a 5R barrel and the throat has only grown .018” over 400 rounds in comp and only 25 rounds for development. The fire cracking is only just starting to be visible.

My 3 groove 6.5x47 has no visible cracking and the throat has only grown .008” in 3 weekends of matches, equating to just over 600 rounds. I hope it keeps going this way.

Cheers.

 

[Capt. Oblivious]

Single base powders burn far hotter than double base powders, which is why it fire cracks earlier.

Just about exactly the opposite as how I understand it???

 

[JBT47]

Just about exactly the opposite as how I understand it???

I’ve always understood from what I’ve read that double base powders such as R17, Viht N550, Viht N560, etc. cause shorter barrel life than single base.

I use both and replace barrels as needed.

 

[MagnumManiac]

Just about exactly the opposite as how I understand it???

Not so, double base powders burn cooler but generate more energy per grain of powder or more specifically the density or it’s specific gravity (SG).

 

[Bart B.]

Here's a heat index table for powders derived from Quickload data. Higher numbers means hotter burning powder

 

[Capt. Oblivious]

Here's a heat index table for powders derived from Quickload data. Higher numbers means hotter burning powderView attachment 1038867

You see thats how I understood it.

N560 double base=burns hot
N160 single base=burns cooler