Reloading new vs. once fired

[canyonman1]

My taxidermist has a 330 Dakota he wants me to figure out. He says it will shoot .5" groups with RL-19 and 225 Hornady Interlocks in new brass. In once fired same load it shoots 3".
The rifle is a custom and has been given the look over and nothing shows.
The barrel has been magna ported.
I've never heard of this has anyone else?
I've shot his rifles on many occasions, and they are top notch. His father is a retired gunsmith (50 Years) and he can't figure it out.
Any suggestions before I try and tackle it?gun)

 

[Tikkamike]

Well does he neck size only? if so maybe the gun likes a cartrige that doesn't fit the chamber tightly?? Try full length sizing the brass to replicate new brass measurements. Maybe the loads are too hot and the brass is damaged? How many of these .5 groups has he shot with new brass? if only once maybe it was a lucky group... I cant think of anything else at the moment.

 

[winmag]

+1with Tikamike.
Might also see if he
1) trimmed the brass
2)if his bullets are seated strait
3)play with the powder charge and primers
Im guessing many powders give the velocity he wants? I know first hand that my short mag shoots tighter groups with hotter loads of IMR. Maybe his rifle doesnt like the load he's using.
''when the mower runns out of gas,check the simple stuff first''

 

[Mikecr]

He might want to try working up a load with fireformed brass.
Afterall, he plans on reloading and using it, right?

He can chronograph his 'new brass' ammo, & match the same velocity with 'formed brass' ammo to get close enough for seating depth tests. Then he'll shoot better than previous with either.

The answer is never to FL size. You can search this and other sites to see all problems, and combinations of problems, with clear common causes: HOT LOADS, OVER SIZING, LACK OF PLANS.

 

[roaddog1m]

Winmag hit on something. I'd check the brass length after firing and sizing. compare it to the new brass length. You may want to get a cast of the chamber for this but since it is a custom rifle, maybe the brass is getting a bit long and pinching the bullet.

Tom

 

[Tikkamike]

I forgot to ask a critical question. is the "NEW" bras in the form of factory ammo or did he reload with new brass that he purchased? What weight bullet does he use and what is the rifles rate of twist? Something else thats easy to forget is the bedding. take the rifle out of the stock and make sure its put together right?? Probably is but like winmag said check the easy stuff first...

 

[canyonman1]

The rifle has been checked top and bottom, inside and out, bedding, barrel, headspace, chamber, etc... Loaded with new brass not factory ammo. 1-10" twist 26" pushing right at 2,900 fps.
Shoots tiny holes till you resize, reload and fire. Neck or full length does'nt matter. Still 3".
I'm going to try RL-22, 25, and H-4831. Then on to primers.
Has anyone ever heard of magnaporting doing this?gun)

 

[roaddog1m]

I think you better try adjusting your sizing die back out. I recently had a similar problem where I was pushing the shoulder back when I resized.

Tom

 

[canyonman1]

Does it with neck sized brass also. Measured everything possible, all o.k...gun)

 

[Tikkamike]

Yeah I am leaning towards your sizing die being set up incorrectly

 

[roaddog1m]

I still think it's the resizing process. Don't adjust your die all the way until it bumps the shell plate. Where ever you have it set now, back it out one full turn and load ten or so. It has to be it! The only reason I'm so adamant about the resizing process is because I just went through something similar. I'm using a set of $130 Redding dies. I know they are good dies but I found out that a die isn't always the same specs as the chamber. (I think the shoulder is being pushed back too far)
I'm no brainiac, in fact, I'm not half as smart as most of these guys on here. (or rich) But I've been handloading for twenty years! Just try it and let us know what happens.

Good luck

Tom

 

[Tikkamike]

Yeah please try it if for nothing other than Tom and I's sanity. I am in 100% agreance with him.

 

[roaddog1m]

Yeah please try it if for nothing other than Tom and I's sanity. I am in 100% agreance with him.

LMAO! Thanks Mike

 

[LRHWAL]

You may just find that the new load it outside of the velocity "node" that the rifle likes. Shoot new brass load over a chrony and load once fired for the same velocity and see how it does.

Some rifles show fairly large differences in velocity between new and fire formed brass. I know the load is the "same" but you haven't indicated whether the velocity was the same.

You can check the once fired brass on a run-out guage for straightness just to be sure as well.

Are you sizing the new brass before seating the bullet? If not you will almost certainly have different neck tension between new brass and once fired and resized brass and maybe the rifle prefers the lighter neck tension of the new brass.

Just my 5 SA cents...