Bolt Close/Lift Tension Question

[BillPa]

Hawk, Not to be a smarty pants but try the 2nd thought 1st. This will prove or dis-prove my hunch. Also give the free-bore a THOROUGH cleaning with a bronze brush and copper solvent to remove any potential build up of jacket/powder material constricting the free-bore. ........ If you can chamber a round with light to no resistance when bearing surface is below neck mouth but can't when bearing surface is above neck you've identified the problem. .....

I agree with you, its a bullet-freebore issue, not a brass issue.


For both rounds the brass chambered easily until I seated a bullet, stiff with bullet seated (at various lengths), and then easily again after I pulled the bullet.

It would also explain ....

I have had it to the range one for break-in and had an issue with a Federal Gold Medal Match 168gr SMK getting stuck in the lands and coming apart and ending my day early.

He should thoroughly clean the chamber first then try it. If the problem still exists then a chamber cast should be made to measure the freebore diameter of the cast vs the bullet shank diameter(s).

Bill

[gotcha]

BillPA, Thanks for clarifying. I have some more input but will wait 'til Hawk can perform the "bearing surface above and below the case mouth" test............. Hawk, No need to dull bullet surface for test that Bill & I outlined. But do look for circular impression around the circumference of bullet caused by a too tight free-bore. Good luck!

[mjphawk]

Well my duck hunt got cancelled so I had some time to work in the garage tonight to try out some of the things that everyone was kind enough to take the time to suggest.

I did a thorough cleaning of the bore and chamber until it was spotless.

I checked the distance from the head to shoulder datum both with and without a bullet seated and there was no measurable difference in the length that would indicate that I am compressing the shoulder with the seating die.

I continued to seat the bullet down until the entire bearing surface was below the case mount and the bolt closed easily (2.0620" base to ogive). The markings on the bullet are from seating depths longer than the one shown. Whatever is making the marking appears to be the same cause of the stiff bolt closing.

http://i1129.photobucket.com/albums/m508/spearch/55AB8CFA-E0F2-4461-9A2E-FDD4162A6591.jpg (http://s1129.photobucket.com/user/spearch/media/55AB8CFA-E0F2-4461-9A2E-FDD4162A6591.jpg.html)

I then pulled the bullet and tried to determine at what point the bolt stiffness disappeared (2.0785"). At 2.0875" the first bolt close is a little stiff but subsequent closings gets easier. I would say this one is right on the edge of where the problem is starting

I then loaded another round at 0.010" short of where I measured the lands to be and steel wooded the bullet. I played around a little with seating depth but nothing extreme. I am getting a mark on the top side of the projectile that covers just under 90-degrees. I believe there may be a burr in the chamber that is rubbing against the bullet and once the extractor grabs the bullet it is twisting the bullet along the burr and causing it to score around circumference of the bullet as I close the bolt and causing the stiffness. Not until I get the bearing surface below the neck to I avoid the contact.

http://i1129.photobucket.com/albums/m508/spearch/D51F19FC-47E2-468B-835D-DB0BBD4DF0E8.jpg (http://s1129.photobucket.com/user/spearch/media/D51F19FC-47E2-468B-835D-DB0BBD4DF0E8.jpg.html)

http://i1129.photobucket.com/albums/m508/spearch/621F0E6F-0C56-4B1D-AAD3-E6B18E59BD65.jpg (http://s1129.photobucket.com/user/spearch/media/621F0E6F-0C56-4B1D-AAD3-E6B18E59BD65.jpg.html)

Even seated fairly deep the relation of the marking on the bullet and the case neck remains the same

http://i1129.photobucket.com/albums/m508/spearch/CF54C7FB-914E-4B01-BCFE-BEA2F97105FE.jpg (http://s1129.photobucket.com/user/spearch/media/CF54C7FB-914E-4B01-BCFE-BEA2F97105FE.jpg.html)

http://i1129.photobucket.com/albums/m508/spearch/276C6063-8F12-4DD2-8CB0-48370EFB295D.jpg (http://s1129.photobucket.com/user/spearch/media/276C6063-8F12-4DD2-8CB0-48370EFB295D.jpg.html)

I also tried a 165gr Hornady A-Max in addition to the 168gr Sierra Match King which I have done most of my testing on but haven't done extensive measuring to know the exact point where an A-Max hits the lands. I didn't get the scoring (or any other clear marking) on the A-Max but the stiffness was still there.

What I don't know now is what the proper next step is. I suppose I need to order a casting kit and make a cast of my chamber so I can measure things. Are the casts accurate to within 0.01" or do they expand/contract enough that the measurement won't be accurate enough for my needs. I also plan to call Savage to talk to someone in their technical support department. I called today but they needed the serial number which I didn't have at the time. I fear their default answer is going to be to send it back and they will end up drilling out or replacing a barrel that I believe is quite accurate. If that ends up being the only solution then I suppose that's what I will have to do.

How long does throat erosion take to erode a few thousandths? The gun has only 25 rounds through it. Would getting another 75-100 rounds down the barrel with a reasonably light load potentially solve my problem? Thanks to everyone for suggestions so far and I appreciate your continued help.

[dcloco]

Blacken the bullet with a sharpie, let the ink dry. This will help to see more of what may be going on.

Is the bullet only being marked at one spot in the throat?

[mjphawk]

Blacken the bullet with a sharpie, let the ink dry. This will help to see more of what may be going on.

Is the bullet only being marked at one spot in the throat?

I first pressed the round into the chamber without closing the bolt. There were not markings. I then did the same and closed the bolt. The only marking is the same line that runs along the circumference of the bullet just above the neck which is in the pictures above as well. No other markings that indicate contact is being made on any other point on the bullet when chambered (did it twice to be sure).

http://i1129.photobucket.com/albums/m508/spearch/8D482627-DA38-48A5-A15F-2A5750AFE10B.jpg (http://s1129.photobucket.com/user/spearch/media/8D482627-DA38-48A5-A15F-2A5750AFE10B.jpg.html)

[dcloco]

Hmmm...rough edge at the freebore. ????

I always sacrifice one case to find seating depths. Full length size a case, two vertical splits from mouth of case to neck/shoulder junction, remove any burrs. Manually control the neck tension by slightly pinching the brass.

[dcloco]

With the same blackened bullet, leave it seated extra long. Would be nice to see where the ogive of the bullet contacts the lands....AND the mark that you have already found.

[mjphawk]

I always sacrifice one case to find seating depths. Full length size a case, two vertical splits from mouth of case to neck/shoulder junction, remove any burrs. Manually control the neck tension by slightly pinching the brass.

Not sure I completely follow here. Are you saying you make a case into an overall length gauge? I have the Hornady gauge and have measured with that and gotten consistent results. Not saying I for sure did everything right. Open to doing things a different way but couldn't picture in my head exactly what to do.

When I redo the black bullet test how far into the lands do you want the bullet to go? I'll seat the bullet to that length which will show the markings as well as confirm my measurements.

[gotcha]

Well my duck hunt got cancelled so I had some time to work in the garage tonight to try out some of the things that everyone was kind enough to take the time to suggest.

I did a thorough cleaning of the bore and chamber until it was spotless.

I checked the distance from the head to shoulder datum both with and without a bullet seated and there was no measurable difference in the length that would indicate that I am compressing the shoulder with the seating die.

I continued to seat the bullet down until the entire bearing surface was below the case mount and the bolt closed easily (2.0620" base to ogive). The markings on the bullet are from seating depths longer than the one shown. Whatever is making the marking appears to be the same cause of the stiff bolt closing.

http://i1129.photobucket.com/albums/m508/spearch/55AB8CFA-E0F2-4461-9A2E-FDD4162A6591.jpg (http://s1129.photobucket.com/user/spearch/media/55AB8CFA-E0F2-4461-9A2E-FDD4162A6591.jpg.html)

I then pulled the bullet and tried to determine at what point the bolt stiffness disappeared (2.0785"). At 2.0875" the first bolt close is a little stiff but subsequent closings gets easier. I would say this one is right on the edge of where the problem is starting

I then loaded another round at 0.010" short of where I measured the lands to be and steel wooded the bullet. I played around a little with seating depth but nothing extreme. I am getting a mark on the top side of the projectile that covers just under 90-degrees. I believe there may be a burr in the chamber that is rubbing against the bullet and once the extractor grabs the bullet it is twisting the bullet along the burr and causing it to score around circumference of the bullet as I close the bolt and causing the stiffness. Not until I get the bearing surface below the neck to I avoid the contact.

http://i1129.photobucket.com/albums/m508/spearch/D51F19FC-47E2-468B-835D-DB0BBD4DF0E8.jpg (http://s1129.photobucket.com/user/spearch/media/D51F19FC-47E2-468B-835D-DB0BBD4DF0E8.jpg.html)

http://i1129.photobucket.com/albums/m508/spearch/621F0E6F-0C56-4B1D-AAD3-E6B18E59BD65.jpg (http://s1129.photobucket.com/user/spearch/media/621F0E6F-0C56-4B1D-AAD3-E6B18E59BD65.jpg.html)

Even seated fairly deep the relation of the marking on the bullet and the case neck remains the same

http://i1129.photobucket.com/albums/m508/spearch/CF54C7FB-914E-4B01-BCFE-BEA2F97105FE.jpg (http://s1129.photobucket.com/user/spearch/media/CF54C7FB-914E-4B01-BCFE-BEA2F97105FE.jpg.html)

http://i1129.photobucket.com/albums/m508/spearch/276C6063-8F12-4DD2-8CB0-48370EFB295D.jpg (http://s1129.photobucket.com/user/spearch/media/276C6063-8F12-4DD2-8CB0-48370EFB295D.jpg.html)

I also tried a 165gr Hornady A-Max in addition to the 168gr Sierra Match King which I have done most of my testing on but haven't done extensive measuring to know the exact point where an A-Max hits the lands. I didn't get the scoring (or any other clear marking) on the A-Max but the stiffness was still there.

What I don't know now is what the proper next step is. I suppose I need to order a casting kit and make a cast of my chamber so I can measure things. Are the casts accurate to within 0.01" or do they expand/contract enough that the measurement won't be accurate enough for my needs. I also plan to call Savage to talk to someone in their technical support department. I called today but they needed the serial number which I didn't have at the time. I fear their default answer is going to be to send it back and they will end up drilling out or replacing a barrel that I believe is quite accurate. If that ends up being the only solution then I suppose that's what I will have to do.

How long does throat erosion take to erode a few thousandths? The gun has only 25 rounds through it. Would getting another 75-100 rounds down the barrel with a reasonably light load potentially solve my problem? Thanks to everyone for suggestions so far and I appreciate your continued help.
Hawk. Excellent photos! It appears to me that your chamber isn't properly located (centered) on the bore. Or, there is an obstruction somewhere in the chamber that's forcing the bullet and/or case to one side of the chamber. This might also be caused by the bolt face not floating or jammed in such a way as to push the cartridge off center into the chamber. If possible send these pic's to Savage and ask their opinion. meanwhile check your ejector and extractor for proper operation. BillPa are you out there?

[mjphawk]

Quick question that I do not know the answer to. Should the extractor grip the casing tight enough that it locks to the bolt face as the bolt is closed? I guess I always assumed the extractor didn't tightly "grip" the case head but given the shape of the marking I am getting on the bullet I can't tell if that is coming from the bullet being pressed tightly against a sharp edge or if it is being dragged along a sharp point.

Seems if the extractor was made to grip the case head that tightly and rotate as the bolt was closed that could cause issues for those bench-rest shooters who seat into the lands so I am assuming the extractor rotates around the bullet but figured it was worth asking if anyone knew.

I will update the thread after I talk to Savage.

[mjphawk]

Well the response was exactly what I thought it would be. Savage suggested I send it back into them so they can take a look at it. I will include much of the write up and pictures from this thread and see what they say.

Good news is that they said they can thread the barrel while they have it in the shop which saves me from having to send the gun out an extra time. Anyone have any horror stories about their ability to thread the barrel straight (I'll likely start another thread in the proper section as well).

Bad news is they are closed until January 5, 2015 so looks like I won't be doing any reloading or shooting over the break. Small price to pay to make sure everything is save. Thanks to all for your input and I will post any updates as they become available.

[BillPa]

BillPa are you out there?

In body, yes, but mentally ??? :p

There is only one way I know of to nail down the problem .....
http://i59.tinypic.com/2vmzxnq.jpg

.... one of those thingys on top. With it and a mic they would tell the tale in short order. Its quite obvious eyeball'n his last set of pictures the bullet major shank diameter is making contacting the start of the freebore. The question is why.

His only two options, send the rifle to the boys and girls at Savage Arms or pay a visit to his local gunwreaker.

Bill

[mjphawk]

In body, yes, but mentally ??? :p

There is only one way I know of to nail down the problem .....
http://i59.tinypic.com/2vmzxnq.jpg

.... one of those thingys on top. With it and a mic they would tell the tale in short order. Its quite obvious eyeball'n his last set of pictures the bullet major shank diameter is making contacting the start of the freebore. The question is why.

His only two options, send the rifle to the boys and girls at Savage Arms or pay a visit to his local gunwreaker.

Bill

Bill,

How difficult is it to do your own chamber cast. I am inclined to do a cast even if I still have to send it back so I can see what the issue is. I assume if it is a manufacturer's defect they are going to send it back with an "all fixed" note and not necessarily let me know what it was that caused the issue in the first place. My only fear is that I do damage to the action in the process of doing a casting.

[BillPa]

Making chamber casts using Cerrosafe isn't difficult but like anything else there's learning curve and requires a little practice.

To get an idea take a look at the "Learn" section on the lower left of this page. > http://www.brownells.com/gunsmith-tools-supplies/barrel-blanks-tools/barrel-chamfering-accessories/cerrosafe-chamber-casting-alloy-prod384.aspx

Bill

[gotcha]

I Agree with BillPa........ I am curious about your pic that shows two circumferential striations on the bullet just above the case neck. Do those marks go all the way around the bullet? If so, can you get a measurement you feel comfortable with that identifies the diameter of the bullet at those specific points? ........ SAAMI spec. (chk. at their site) calls for a free-bore diameter of .310", +.002", minus "0". So any measurement less than .310" indicates the possibility of an under dimensioned free-bore. However, the chamber cast would be "the proof in the pudding" Just something you might want to tinker with while waiting for Cerro-safe since you seem to be the curious type :) :) .............. Keep us posted!! Merry Christmas

[mjphawk]

The straitions only cover around a 90-degree portion of the circumference and do not go all the way around. I am 99.9% confident in my memory that the parallel markings are from the same issue at two seating depths and not form a single chambering.

The bullet diameter is exactly 0.308 (imagine that) at all points i measured along the bearing surface.

I am looking forward to getting the Cerrosafe and seeing what it shows.

Merry Christmas to everyone and your families!

[gotcha]

Sounds like a plan. Don't get into the Eggnog too heavily and all should work out.

[Robinhood]

Have you tried the full length sizing die?

[mjphawk]

Have you tried the full length sizing die?

Yes I did. I tried with both resized and fire formed brass. The bolt closes easily with just the brass and it isn't until I seat a bullet that I start to have a problem.

I was out of town for the New Year but plan to get to doing the chamber cast this weekend and will post the results here when I do.

[stomp442]

Oops I failed to notice this thread was three pages. Never mind what I originally said its been covered.