Are these tumbling? 225 gr Hornady BTHP's in 300 WM

[cowboyarcher]

This may sound out there but I had a target look similar. I was shooting a 45-70. I had printed the targets off my printer at home on standard thin copy paper. The cardboard I has stapled to had been shot out pretty good. When the bullet went through the paper it would get some tearing and it looked like it was keyholeing but the paper was thin and it was actually tearing around the bullet hole. I can't tell if you printed your own target or not or the condition of the cardboard backing. I hope this helps you.

It's hard to see in the photos but the bullets were going through the cardboard sideways, there is enough there that in person it's hard to miss. Interesting thought though!

 

[bigngreen]

Have you checked the brake for any signs the the bullet is touching it. The last time I saw a bullet going side ways from what should be a stable twist it was caused by severe fouling.

 

[cowboyarcher]

Have you checked the brake for any signs the the bullet is touching it. The last time I saw a bullet going side ways from what should be a stable twist it was caused by severe fouling.

The brake is more of a magna port type design as it was milled into the barrel. But I have not examined it to see if there might be an issue there. . .

 

[bigngreen]

It's not so much the brake causing the issue but if the bullet is going horribly sideways early it may show on the brake and indicate another issue other than twist rate. Have you verified twist rate.

 

[cowboyarcher]

I see what you are getting at. I'll check the brake for any strange signs.

I have verified the twist rate with the cleaning rod method and it is almost exactly 10".

 

[westcliffe01]

Have you shot other boat tail bullets out this rifle ? Another poster on here had a terrible time trying to shoot Berger Bullets and later found he could shoot flat base bullets fine. Apparently that points to a throat that is too large in diameter and results in erratic performance with BT bullets. You might try some lighter boat tail bullets like the 185 or 190 Bergers and then compare to similar weight flat base bullets.

At Bullet Samples for Sportsmen Rifles you can buy small qty's of bullets for this type of testing.

Of course flat base bullets are not good for long range shooting and fixing this issue means another barrel, but at least you will know and can decide how to deal with it.

 

[cowboyarcher]

I've got some Hornady BTSP 190's that I was thinking would serve as a good test so that was my next step. If they are erratic I think I might just send it to Sinman and let him do his thing, set it in a B&C and call it a $1000 rifle. I really like what the 300 WM does with heavy bullets so I'm fairly committed to making these 225s shoot.

I'm out of town the next 3 weeks so look for an update sometime in June. . .

Thanks for all the help fellas, God bless you,

Adam

 

[bigngreen]

With a 1-10 that is not the issue, if it was speed related it would take more yardage to show up and it usually shows up with dropping a bullet low every once in a while. Make sure sure the bore is in good shape and not whanking the bullet causing thing to go side ways so early.

 

[cowboyarcher]

You are positive that you were not hitting low and having the bullet ricochet up at the target ? You don't mention the shooting distance, but I would expect a 225 to hit lower than a 150 at short range simply due to the time of flight being longer and it would therefore be dropping more. Whats the difference in MV ? Should be at least 300fps right ? At long range the 225 would retain a lot more energy and would end up going faster than a 150 and thus would actually drop less at the end.

Well I am embarrassed to say it, but this is the group I just shot, with yardstick to indicate how much they were dropping:

Do the holes still seem a bit odd?? It is clear from how much lower they are hitting that these were doing exactly as you thought.

These were at 100 yards w/ some cross wind and were over 76 gr of Retumbo. These gave me sticky extraction so it looks like I need to go no higher than 75 gr and work with seating depth some.

 

[LtBlue425]

I suppose it's possible they were hitting the dirt, but there was only the one dust cloud on the first shot. I suppose I should shoot a group at 25 and 50 just to double check. These were fired at 100 yards.

The only time I had bullets hitting dirt in front of a target was using 77gr bullets in a Rem 22-250. They were so wildly unstable they were hitting the hit 25-50 yds out from the bench. No wonder they won't the paper. lightbulb

 

[BergerBoy]

I just measured one and I got 1.582 inches. My Bergers are a little longer OTMs and Target 230s.

I have a 9 twist on my rifle so I have a SG of 1.94 Anything over 1.4 is deemed as stable by Mr. Litz.
When I run the numbers with a 10 twist it is 1.57 so you should be fine but I agree with the gentleman that said "if your getting anything other than a nice round hole you have some tumbling going on...." It looks like that is what is going on IMO.

Good luck and God Bless this country.