Seating problems Sierra 69gr hpbt Match King

[Critter183]

I just finished 20 rounds of .223 using Sierra MatchKing 69gr hpbt bullets. I had my RCBS seating die set for an OAL of 2.250. 5 of the 20 landed at either 2.245 or 2.255.

Does this mean that 25% of these bullets are misshaped? Or can something else be doing this?

All of the brass was once fired (by me) UMC.

 

[Bullet]

What you are seeing is pretty much normal when not using custom bullets. This is also why when loading close to or into the lands you don’t measure OAL, but rather to the ogive. If you’re loading to fit in a mag just go with the longer OAL. Your seating die is seating the same every time it’s just the difference in bullet shape probably in the meplat.

http://www.sinclairintl.com/cgi-bin/category.cgi?category=search&item=05-49XX&type=store

 

[wanderinwalker]

Likely variations in the bullet tips. Hollow point match bullets are awful about this. As long as they fit the magazine, go with it.

FWIW, I don't know the OAL variation in my AR match bullet loads, and with the right powder/bullet combination, they can shoot MOA.

 

[Critter183]

Your seating die is seating the same ever time it’s just the difference in bullet shape probably in the metplat.

That's what I figured. I just never ran into as many or as large a variation with any other Sierra bullets I have used. I have mostly reloaded .308, .243, 6.5mm and 7mm, and as anal as I am, I would have noticed if 5 out of 20 had come up that far off. lol

 

[Critter183]

FWIW, I don't know the OAL variation in my AR match bullet loads, and with the right powder/bullet combination, they can shoot MOA.

What OAL are you shooting for when you reload for your AR?

This is my first crack at reloading for my AR. The rifle loved the SA Surplus stuff and shot sub 1 moa at 200 meters with it. I checked their average OAL and came up with about 2.245. I read somewhere that 2.250 was recomended, but that I could go as long as 2.260 and still feed it.

I went with 2.250 The 5 that missed and ended up shorter or longer, I will use to get the gun back on the paper once I get my scope back from its rehab trip. lol

 

[Bullet]

The OAL you used 2.250 is probably a good length. With your seating die set here if some are longer they will still fit in your mag. You probably could set your die .005 longer if you want and still keep all your OAL’s under 2.260. I don’t think you will see a difference on target with the variances in OAL you describe, but you could group your cartridges by OAL and see if you can tell a difference.

I also shoot 69gr SMK’s. Once I set my seating die I just run them all through and shoot. No other sorting.

 

[Critter183]

I'm going to do another batch after I get my scope back. Once I get it zeroed, I will sort some rounds by OAL and report back on the results.

Thanks!

 

[mc223]

Measure the inside length of your magazines and set your COL based on the shortest one encountered.

Quick hint: 25.3 grains of Varget will snug up the groups with the 69s.

another tip: using the bullets you will be loading. apply a small amount of lapping compound to a bullet and the seating plug and lap the shape of the bullet into the plug. This takes some patience, which I have very little of, so I just put my seater plug in a vice and chucked the bullet into a hand drill. took about an hour.
This also will reduce the seater plug ring that you may see when seating bullet over those slightly compressed charges.

 

[YodaVader]

This is also why when loading close to or into the lands you don’t measure OAL, but rather to the ogive.

The 69 Sierra is one of my favorites in my 700 LTR and when measuring the OAL to the tip with calipers can get a few thousands variation. But when using a Stoney Point tool attached to my calipers (that measures to the ogive) the the length measurement is extremely consistent.

 

[wanderinwalker]

What OAL are you shooting for when you reload for your AR?

Between 2.25" and 2.26". I know that if I put my calipers on the first 3-5 off of the press, and they measure out within that range, I can just seat and go. I *knock on wood* have yet to have an issue with having a bullet end up too long to fit in the magazine using this.

I'm pickier about my 80gr long-range loads, and have a comparator now for the next batch. I like to load these around .020" off of the lands. There is too much variation in bullet tips to just go with an OAL reading for this, IMO. But again, I won't dial and adjust each one. Just see if the first 3-5 fall within tolerance range and plug along.

Now some bullets you must be more careful with. I just found last night that the 52gr Hornady HPBT can be seated INTO the rifling of my rifle and still fit the magazine. I actually have to seat these to about 2.21" to get them off of the rifling. They hit the lands at 2.225" OAL, so I can't just "seat to length" like I do with the heavier, more rounded ogives of the big bullets.

Good luck.

 

[Critter183]

But when using a Stoney Point tool attached to my calipers

ooooh, I need me one of those. hehehe

 

[Critter183]

Between 2.25" and 2.26". I know that if I put my calipers on the first 3-5 off of the press, and they measure out within that range, I can just seat and go.

Thanks. I probably shouldn't be as fussy as I am, but I get stuck in the "zero tolerence" mode sometimes. hehehe

 

[dmftoy1]

Anyone have a link to that Stoney Point tool? I've searched Midway but not had any luck.

 

[Bullet]

Sinclair has them –

http://www.sinclairintl.com/cgi-bin/category.cgi?category=RESDTCO&type=store

I like these myself –

http://www.sinclairintl.com/cgi-bin/category.cgi?category=RESDTCO&item=09-600&type=store