Hey guys, having some problems with my hunting rig. It's a savage short action with a shilen CM sporter chambered in 260 with an 8 twist. The bore started fouling and accuracy fell at a little over 130 rounds. I continued shooting it now has 430+ down the tube. I broke the barrel in per shilen recommendations, enjoyed match accuracy 1/2 moa for 100 rounds,then groups opened up and accuracy fell. I always clean my rifles thoroughly after shooting, this one I even tried cleaning between groups. As far as shooting/ cleaning..... Nothing improved. Last week I had the barrel bore scoped by a gunsmith, he says it has heat cracking in the throut area and at rifling. He showed me, and I was more than surprised. Can throut erosion begin at just a hundred rounds? He also said that the heat cracking was only aligned in one specific area, and this was causing the bullet to scrap and cant thus resulting in copper fouling and loss of accuracy. I called Shilen and told them and I sent the barrel back to them. Do you think Shilen will replace the barrel? Did I just get a bad barrel?
Heat cracking
- Thread starter Fireformed
- Start date
Wondering if either or both of you are using a high intensity powder - Reloader 17, Vihtavori 500 series, Hodgdon 100HV? I had the same experience with a .308 barrel after using Reloader 17 and heavy bullets. Just about 100 rounds and firecracking had just barely started. I lapped the throat and went back to Varget. Seemed to have caught it in time but no doubt that barrel's life has been shortened. That said, I have a Weatherby 300 chrome moly barrel with several hundred rounds using Re17 down the tube with no apparent ill effects. Wondering is stainless is more prone to heat damage than chrome moly?
dmoran
Donovan Moran
If your seeing fire-cracking on shiny blue steel, it is cracking.
If your seeing fire-cracking on discolored steel, it is carbon layer.
Betting you have not got the thin (stubborn) carbon layer cleaned out of the barrels, and that is what your seeing cracked.
I've never seen normal calibers yet to fire-crack a barrel as soon as you guys are stating. But I have seen apparent cracking of carbon layer, in any barrel, caliber, and round-count. Get the barrel cleaned down to shiny blue steel, and the apparent will be gone as well.
Donovan
If your seeing fire-cracking on discolored steel, it is carbon layer.
Betting you have not got the thin (stubborn) carbon layer cleaned out of the barrels, and that is what your seeing cracked.
I've never seen normal calibers yet to fire-crack a barrel as soon as you guys are stating. But I have seen apparent cracking of carbon layer, in any barrel, caliber, and round-count. Get the barrel cleaned down to shiny blue steel, and the apparent will be gone as well.
Donovan
Mostly loaded 4831, H4350, and RL19 for this one. I've tried the VN550 but only 25 rounds. The barrel liked the 4831 best, H and IMR.
The only loading variation or difference I experienced with this rifle is using Nosler brass. I mostly used RP and federal brass in this 260. When I used the nosler with 44 gr of imr 4831, I had hard extraction/bolt handle lift on the first loading, that seemed very odd to me. (BTW temps were in the 40's and I've never shot this rifle hot)I've never had that with federal, RP, or lapua. The nosler brass showed no pressure signs, primers were normal to still rounded, no marks on the case head, the necks looks smoked more than usual. I checked them, cleaned and resized them and loaded them again with no problems. I loaded all 50 cases twice with no problems....I think....
Before the barrel was bore scoped it was thoroughly cleaned. When looking at the fire cracking it was on bare metal, most of the carbon was cleaned out. I could see clean steel at the cracking, also visible was green residue from the copper cleaner I used. The gunsmith also said the tooling marks from the button rifling along the entire bore were excessive, he said "Lots of chatter". The barrel was not hand lapped at shilen when is was made.
The only loading variation or difference I experienced with this rifle is using Nosler brass. I mostly used RP and federal brass in this 260. When I used the nosler with 44 gr of imr 4831, I had hard extraction/bolt handle lift on the first loading, that seemed very odd to me. (BTW temps were in the 40's and I've never shot this rifle hot)I've never had that with federal, RP, or lapua. The nosler brass showed no pressure signs, primers were normal to still rounded, no marks on the case head, the necks looks smoked more than usual. I checked them, cleaned and resized them and loaded them again with no problems. I loaded all 50 cases twice with no problems....I think....
Before the barrel was bore scoped it was thoroughly cleaned. When looking at the fire cracking it was on bare metal, most of the carbon was cleaned out. I could see clean steel at the cracking, also visible was green residue from the copper cleaner I used. The gunsmith also said the tooling marks from the button rifling along the entire bore were excessive, he said "Lots of chatter". The barrel was not hand lapped at shilen when is was made.
BigDMT
Yeah I have been trying to break in a Shilen CM on my son's rifle and although it shows promise for great accuracy, the bore has excessive tooling marks and copper fouls horribly. The tooling marks are as bad as any factory barrels I've seen. Of course I suppose every barrel looks that way before it is hand lapped. Unfortunately Shilen does not hand lap their Chrome Moly barrels unless you specifically request it and pay an extra charge. All their SS barrels come hand lapped
The fire-cracking on the one side may be due to a crookedly cut chamber on the bore. But not sure why you are seeing any cracking so soon?
Anyhow, don't be discouraged, excellent accuracy can still be achieved with some fire-cracking in the throat area. Just might have to tweak your load a bit and perhaps chase the lands. If you are loading ANY 6.5mm round at max where it is pushing high pressure, they will wear the throat out like nothing else. Any 6.5 chambering can be a real barrel burner if pushed hard.
David Tubb makes throat polishing bullets that are specifically designed to help with that type of throat erosion. They are called the TMS (Throat Maintenance System) bullets. They have excellent reviews and feedback across the board. I am actually planning on trying them in my son's CM Shilen barrel because standard bullets don't seem to be smoothing the bore out very well at all. I also have another CM Shilen on another rifle I haven't fired yet. I think I might use the David Tubb TMS bullets on it right off the bat just to see if I can shorten the break-in round count. Because right now, I feel like I am almost wasting bullets on my son's rifle. But it's shooting good so I can't complain too much
The fire-cracking on the one side may be due to a crookedly cut chamber on the bore. But not sure why you are seeing any cracking so soon?
Anyhow, don't be discouraged, excellent accuracy can still be achieved with some fire-cracking in the throat area. Just might have to tweak your load a bit and perhaps chase the lands. If you are loading ANY 6.5mm round at max where it is pushing high pressure, they will wear the throat out like nothing else. Any 6.5 chambering can be a real barrel burner if pushed hard.
David Tubb makes throat polishing bullets that are specifically designed to help with that type of throat erosion. They are called the TMS (Throat Maintenance System) bullets. They have excellent reviews and feedback across the board. I am actually planning on trying them in my son's CM Shilen barrel because standard bullets don't seem to be smoothing the bore out very well at all. I also have another CM Shilen on another rifle I haven't fired yet. I think I might use the David Tubb TMS bullets on it right off the bat just to see if I can shorten the break-in round count. Because right now, I feel like I am almost wasting bullets on my son's rifle. But it's shooting good so I can't complain too much
I finally got a call from Shilen. It turns out the chamber was cut too long. They did not say how much it was over. 1/2 thou?... So I'm guessing the heat cracking was caused pre maturely because of excessive pressure. I have always installed my savage barrels with a go gauge, so I didn't have excessive head space. Or did I? Could the gauge not have contacted at the shoulder and fitted itself to the side of the chamber at the case body? Cases were going into the chamber too far. I'll need to look back at my brass and loading log and do some measuring.
Shilen is replacing the barrel at no cost (aside from shipping bad barrel)with a stainless select barrel.
Shilen is replacing the barrel at no cost (aside from shipping bad barrel)with a stainless select barrel.
No clue what that is about, I would have to ask Shilen how the 'too long' chamber could cause high pressure. To build pressure the case must expand to fill the chamber, if the case fits the chamber as in neck sized it takes less time for pressure to build.
FireForned or fire formed? I would suggest you use a comparator to determine the length of the case from the shoulder to the head of the case after firing. You adjusted the length of the chamber from the shoulder of the chamber to the bolt face with a head space gage, to verify you can fire a case and then measure the length of the case from the shoulder of the case to the head of the case, case formers form cases first then fire.
F. Guffey
Ya that's what shilen said, chambered too long...don't know why they'd lie about it. Maybe because guys post on forums like this about getting a bad barrel. :
I am no expert or know it all by any means. I like to target shoot, reload, and hunt on occasion. I do know how to measure headspace. I keep a log for headspace on fired cases. I looked through my data and everything looks normal. New brass to 3rd firing increased normally and I neck sized only.
Looks like I got a bad barrel from shilen, but they are replacing it at no charge and I'll have a new barrel in 2 weeks.
I am no expert or know it all by any means. I like to target shoot, reload, and hunt on occasion. I do know how to measure headspace. I keep a log for headspace on fired cases. I looked through my data and everything looks normal. New brass to 3rd firing increased normally and I neck sized only.
Looks like I got a bad barrel from shilen, but they are replacing it at no charge and I'll have a new barrel in 2 weeks.
Shilen replaced my barrel as promised, they sent me a select match stainless barrel. I have a little over 400 rounds through it. Currently it's my new favorite. It shoots the 120s like a laser, .3 regularly and a few .2, clean up is easy compared to a factory remington or savage.
It is possible that it was throated too long...in which case you would not have an excessive headspace issue.
Glad to hear Shilen is making good on their products. I hope your new barrel is a shooter! Sam
Glad to hear Shilen is making good on their products. I hope your new barrel is a shooter! Sam
Throat erosion and fire cracking is a cumulative process, it starts with the first round and ends with the last round. There are several factors, the first being heat and pressure, neither are your friend. Over bore cartridges are more destructive due to the time duration of the heat and pressure.
Example:
A .243 Win., in a 30", 1:8, barrel shooting shooting a 105 grain bullet at 3300 fps (hot load of VV 160 or IMR 4350) expected barrel life 900-1100 rounds.
A. 6mmBRX., in a 32", 1:8, barrel shooting a 105 grain bullet at 3050 fps (Hot load of Varget) expected barrel life 2800-3600 rounds.
The barrels are the same, the velocities are 150 fps difference. The volume of powders are different by 30%. And the .243 barrel life is 30% of the 6mmBrx.
The cost of shooting the 6mmBRX is 30% of that of the .243.
For target shooters this is a no brainer and why the BRX and Dasher are favored.
Besides inherent accuracy of the BR class cartridge, good component availability, and less recoil.
Nat Lambeth
Example:
A .243 Win., in a 30", 1:8, barrel shooting shooting a 105 grain bullet at 3300 fps (hot load of VV 160 or IMR 4350) expected barrel life 900-1100 rounds.
A. 6mmBRX., in a 32", 1:8, barrel shooting a 105 grain bullet at 3050 fps (Hot load of Varget) expected barrel life 2800-3600 rounds.
The barrels are the same, the velocities are 150 fps difference. The volume of powders are different by 30%. And the .243 barrel life is 30% of the 6mmBrx.
The cost of shooting the 6mmBRX is 30% of that of the .243.
For target shooters this is a no brainer and why the BRX and Dasher are favored.
Besides inherent accuracy of the BR class cartridge, good component availability, and less recoil.
Nat Lambeth
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