KEY HOLE PROBLEM

[drstrangelove]

I read a thread this morning about a March this weekend with three different shooters, shooting three different calibers having 147 bullets blow up mid-flight. My money is on bullets at this point. All three shared the same lot number.

Can you post the lot number?

 

[vortech347]

They come apart in 1:8 Creedmoors. It's not the gun or the twist rate that is the problem.

 

[nkyshooter]

I have done and or in the process of doing all of the above, except removing brake. all looks good through bore scope. explain reason for removing brake, Thanks

Hi Foul bore ... reasoning for suggesting brake removal is as simple as variable elimination and nothing more.

Good luck!

 

[Cesky fousek]

I have a browning Xbolt long range max in 6.5 PRC 7" twist 26" heavy sporter with a random key hole problem (see attached ) shooting 147 gr ELD match, H1000 or H4831SC moderate loads. action is torqued per mfg specs scope as well. bedded and full floated, I am shooting off a Sinclair F class bipod and rear bag. when I say random it may be 3,4, 5th shot, not over heated. I am very carefull with reloading, ES 12, SD 4.3, seat depth .050, neck tension seems fine. I am lost, never had this problem with any other guns, first plastic stock I ever had, I am thinking stock, bipod problem? HELP!! hop JE responds to this. Thanks for any ideas. Jim

I had the same problém

I have a browning Xbolt long range max in 6.5 PRC 7" twist 26" heavy sporter with a random key hole problem (see attached ) shooting 147 gr ELD match, H1000 or H4831SC moderate loads. action is torqued per mfg specs scope as well. bedded and full floated, I am shooting off a Sinclair F class bipod and rear bag. when I say random it may be 3,4, 5th shot, not over heated. I am very carefull with reloading, ES 12, SD 4.3, seat depth .050, neck tension seems fine. I am lost, never had this problem with any other guns, first plastic stock I ever had, I am thinking stock, bipod problem? HELP!! hop JE responds to this. Thanks for any ideas. Jim

i'm willing to make a wager that you are shooting with their muzzle brake Which wasn't designed for 6.5 mm
Please take the muzzle brake off and you will the difference

 

[jimirwin]

I have a browning Xbolt long range max in 6.5 PRC 7" twist 26" heavy sporter with a random key hole problem (see attached ) shooting 147 gr ELD match, H1000 or H4831SC moderate loads. action is torqued per mfg specs scope as well. bedded and full floated, I am shooting off a Sinclair F class bipod and rear bag. when I say random it may be 3,4, 5th shot, not over heated. I am very carefull with reloading, ES 12, SD 4.3, seat depth .050, neck tension seems fine. I am lost, never had this problem with any other guns, first plastic stock I ever had, I am thinking stock, bipod problem? HELP!! hop JE responds to this. Thanks for any ideas. Jim

I suspect the moderate loads....too light ... insufficient velocity.

 

[foul bore]

I read a thread this morning about a March this weekend with three different shooters, shooting three different calibers having 147 bullets blow up mid-flight. My money is on bullets at this point. All three shared the same lot number.

WOW, mine all have the same lot number, I tried to get them like that. To all that have responded, Thanks. I would have never figured out the bullet blow up issue.

 

[Hugnot]

The Hornady 4DOF calculator defaults to a 7 twist for that bullet giving a "gyro" value of 2.17 at 2900 fps, at muzzle. My guess, from looking at the target that shows a funny looking bullet hole ("L" shaped) is that the bullet jacket failed. The long skinny 147 needs a fast twist to stabilize. The 4DOF calculator with an 8 twist comes up with a "gyro" value of 1.66 at muzzle. Both values using default environment values. Spinning like crazy but as needed for stability.

 

[foul bore]

attached is pic of Hornaday 147 shows 1-8.5 twist mine is 1-7.5 confirmed manufactuer list at 1-7 batch # if interested

 

[DJ Fergus]

attached is pic of Hornaday 147 shows 1-8.5 twist mine is 1-7.5 confirmed manufactuer list at 1-7 batch # if interestedView attachment 219009

I really don't think twist rate is your problem but I would physically check it just so you know and you have a better guess at what grain weight bullet would likely give you the best accuracy. I'm not just picking on Browning but I had two out of three xbolts that didn't have what they advertised for twist rate. I've had one savage, one Remington, and one custom barrel in which twist rate was not what was advertised. Not that I necessarily had accuracy issues with any of them, but that did keep me from shooting the bullet I wanted to be able to shoot accurately on two of those rifles.

 

[foul bore]

I really don't think twist rate is your problem but I would physically check it just so you know and you have a better guess at what grain weight bullet would likely give you the best accuracy. I'm not just picking on Browning but I had two out of three xbolts that didn't have what they advertised for twist rate. I've had one savage, one Remington, and one custom barrel in which twist rate was not what was advertised. Not that I necessarily had accuracy issues with any of them, but that did keep me from shooting the bullet I wanted to be able to shoot accurately on two of those rifles.

did physically check it 4 times it is 1-7.5 not 1-7. 147 should have worked

 

[DJ Fergus]

did physically check it 4 times it is 1-7.5 not 1-7. 147 should have worked

Yeah, I agree. I don't think 7.5 twist should hinder you any at all. My bad for missunderstanding your prior post of 7.5 twist.

 

[markl]

I have a 6.5 PRC barrel on order from Kelbly's, a friend told me that 6.5 PRC are having problems with 5 land barrels. He said people are going to 4 land barrels to overcome the problem, I asked Ian Kelbly about this. Ian assures me that they have had no problems with with the 5 land barrels, he did say that he had read about the problem on the internet.

 

[DJ Fergus]

I have a 6.5 PRC barrel on order from Kelbly's, a friend told me that 6.5 PRC are having problems with 5 land barrels. He said people are going to 4 land barrels to overcome the problem, I asked Ian Kelbly about this. Ian assures me that they have had no problems with with the 5 land barrels, he did say that he had read about the problem on the internet.

I would be surprised to see a problem either way 4 or 5 groove but I would say if there was any likely hood of a problem at all it would be lessened with a 5 groove.

 

[Zorack]

about 350

Have you tried a heavier bullet like a 156 eol berger or the 150 SMK?