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Damaged Crown
Posted: Sun Mar 08, 2015 12:08 pm
by Vpees
Hi guys,
I'm new to the site and have just got a second hand Savage Mod 12 in 204.
Closer inspection of what looked to be a recrown shows no bevel or chamfer from the face of the 90 deg recess to the lands.
Looking on line this should be 60 deg and about 20 to 30 thou.
I took it to the range and the grouping was like a shotgun pattern...
Would the lack of a proper crown job impact accuracy that much?
Is the recessed crown the best option or the 11 deg better?
Keen to understand if this is recoverable or indicative of the need for a new barrel
Many thanks
Ps. I was using factory amo (hornady 32 grn) and shooting 300 yards, grouping was 12" +
Bore was cleaned and had quite a bit of fouling.
Re: Damaged Crown
Posted: Sun Mar 08, 2015 4:59 pm
by 22 Mag
Vpees
I picked up a crown polishing tool from Midway. It looks like a small brass ball on the end of stick and the kit contains three different grades of polishing compound.
I had a 7-08 with a damaged crown that shot 2" 3-shot groups, that now shoots a small cloverleaf 3 shot groups. It took about 1/2 hours worth of work and then a very good cleaning to make sure the polishing compound is removed from the barrel.
The other part you will need is a 10X jewelers lope, so you can see when the crown has sharp edges and a Q-tip to help find burrs.
Not hard and kind of fun to do. Good luck
22 Mag
Re: Damaged Crown
Posted: Sun Mar 08, 2015 6:41 pm
by skipper
A damaged crown will certainly result in a negative impact to accuracy. If you are certain the crown is the problem it needs to be addressed. Some believe a straight cut 90 degree crown is the best others swear by a recessed crown or XX degree. Whichever you prefer, a re-crown job by a competent gunsmith would probably be well worth the expense. Absolute squareness with the bore is the goal. Then guard it from bore brushes or anything else that might damage it.
Re: Damaged Crown
Posted: Tue Mar 10, 2015 12:09 am
by Vpees
Thanks guys ...
I took it to the gun smith and he said it look fine and the spread I was getting was more likely due to shooting in the rain ... Warm barrel and the rain cools to top half causing a very small bend causing vertical stringing .... I had an empty case and a 40 grn projectile and he tested the projectial in the end of the barrel and eyeballed the rifling and said all was good.
I then noticed that the shoulder on the fired case and the unforced case was rounded and not a defined angle like an unfired winchester round...
He suggested the following..
Shoot it at 100 yrds on a fine day and try different manufacturers .... I got the feeling there may have been a know issue with some Hornady factory rounds???
I might try and load some images as the rounded shoulder case looks very odd
Thanks for the replys and info ...
Looking for forward to tight groups (wet or fine)....
Re: Damaged Crown
Posted: Tue Mar 10, 2015 9:43 am
by futuretrades
Something I don't understand here, is why do you want to shoot at 300 yards to see what your
unfamiliar rifle will do as far as groups.
IMHO the 32's would not be my choice for checking groups at 300 yards in the first place, especially not knowing the twist of said rifle. The 39grs might be a better choice. I would suggest try shooting at 100 yards and make sure it isn't
raining Make sure you have a good solid bench or such to shoot off of. Also no mention of the the rest you were shooting off of. The barrel should be checked to make sure it is free floated, and nothing touching the barrel!
Vpees wrote:Bore was cleaned and had quite a bit of fouling.
Are you sure the barrel was clean? Did you make sure all the copper deposits were gone? A little more detail about what you did to clean the barrel, before shooting this rifle.
We need a little more detail on your part, before we can suggest something that will help with that 204R.
Re: Damaged Crown
Posted: Wed Mar 11, 2015 11:54 am
by Vpees
Thanks, and all good points ...
Rifle is a Savage Moddel 12 Varmint Low Profile with laminated wooden stock and fully floated stainless steel fluted bull barrel with box magazine.
We shoot at 300, 500 & 600 yrds each Saturday when possible and I use a Harris bipod and rear sand bag (prone position). I normally shoot a 7mm08 at these ranges.
When I got the rifle I used hoppes #9 on a mop serval times with wet then dry patches Until they came out clean, and than did it again to make sure.
My original concern was the crown, but after having talked to my gun smith he checked it out and the rifle and said all looked fine. He also mentioned that the rain can have an impact on grouping but I have not seen it to this extent. Then I noticed the rounded shoulder on the hornady case when compared to a winchester case (rounded shoulder on fired and unfired case), the gun smith suggested I try on a fine day at a closer distance (100 yrds) and try some different brands. So my plan is to do this this weekend.
I think I have rushed it a bit as I hear great things about the round and was keen to see some results.
Cheers
Re: Damaged Crown
Posted: Thu Mar 12, 2015 12:47 pm
by futuretrades
Vpees wrote:We shoot at 300, 500 & 600 yrds each Saturday when possible
OK that explains why you went right to 300 yards . But you need to know where the bullet is grouping at 100yds first. This will at least tell you something about the rifle and bullet you are shooting.
I would suggest trying the 39 gr SBK's at those ranges. IMHO it is my belief these are a more accurate bullet than the Vmax. I shoot them at our Belding squirrels, when the shooting is longer ranges, and when the wind comes up.
Vpees wrote:When I got the rifle I used hoppes #9 on a mop serval times with wet then dry patches Until they came out clean, and than did it again to make sure.
Hoppes #9 will not get the copper out of the barrel, no matter how many times you swab it out. Lots of other cleaning products will take care of the copper. My personal choice is Barnes CR-10. The problems with smaller calibers is the copper fouling.
Anybody that has been shooting these smaller calibers for any length of time can tell you this.
When I used to shoot my 270 a lot, before I knew about problems with copper fouling, I was using Hoppes on it also. But I did notice a difference with my groups over a period of time. I finally got some info on the subject of fouling, and used the CR-10 on it, the groups tightened right up again.
Re: Damaged Crown
Posted: Mon Mar 16, 2015 5:07 pm
by Vpees
Good news!!!
Got some Slip 2000 Copper cutter and cleaned and cleaned and cleaned ...
Bore is now clean!
Hornady grouping 2/3" and Winchester 3/4" @ 100 yards using bypod and rear sandbag.
Still a bit of wind from 160 deg so I'm sure there is room for improvement . Of note the Hornsby brass still had the rounded shoulder and the Winchester a squarer one so I will see how reloading goes now my dies have arrived.
I will have a look at the reloading forum for any info on Berger options.
Just a quick footnote on shooting in the rain, most of the info I have read talks about bullets hitting rain drops that may have a small impact on accuracy but nothing on shooting "in" the rain with wet cartridges and a barrel that is wet on the top 1/2 and warm on the bottom 1/2... I'm sure this had something to do with the initial poor grouping.
Thanks for your ideas and input ...
Tight groups
Vp
Re: Damaged Crown
Posted: Mon Mar 16, 2015 5:50 pm
by skipper
That's good news. Saves a ton of money, too.
Those cases you fired in your rifle are now fire formed under pressure to conform to THAT rifle's chamber. You might want to try just neck sizing them with a bushing die. Retaining the fire formed shape is desirable from an accuracy perspective. When the bolt gets hard to close then you can bump the shoulders back a bit so they will chamber more easily.
Re: Damaged Crown
Posted: Tue Mar 17, 2015 12:21 am
by Vpees
Yes,
I have been told that the Lee dies are good due to neck sizing only as there is no button to expand on the up stroke ... Less metal fatigue /potentail for splitting ...
Need to get onto those magpies at 250/300 yards plus, challenge is flat land and no cover
Cheers
Vp
Re: Damaged Crown
Posted: Fri Mar 27, 2015 1:31 am
by Bodei
I use a Lee neck sizing die for my 204 and it works great. You should be able to get those groups to 1/2" or less with some hand loads. RL-10x and 8208xbr are my favorite powders.
Re: Damaged Crown
Posted: Fri Mar 27, 2015 5:24 pm
by Tokimini
Vpees wrote:Rifle is a Savage Model 12 Varmint Low Profile with laminated wooden stock and fully floated stainless steel fluted bull barrel
Is the tang on the rear of the action free floated? If it's not it can have a serious effect on accuracy with Savages.
Re: Damaged Crown
Posted: Fri Mar 27, 2015 6:15 pm
by hemiallen
Interesting on the tang. I assume these are 3 screw guns and the center/ front hold it well enough?
How is Victor for snow? I am now retired and it's been 2+ years since I had the pleasure to visit Rochester and Victor on my way to the Antique store. Hope all is well, I have seen a lot of foul weather reports lately for you upstate folks.
Allen
Re: Damaged Crown
Posted: Sat Mar 28, 2015 5:55 pm
by Tokimini
Allen,
The snow and cold were tough but we're through the worst of it, I hope.