243 target loads

[105gr]

I'll try to post as many details as I can....first off I'll start with I have only been reloading about a month. I have a 1976 Remington 700 BDL heavy barrel in .243 with a 1:9 1/8th twist. The barrel has been cut to 16 1/2" and has a registered suppressor on it all the time. I'm using Remington R&P brass which really appears to be good brass compared to the garbage winchester stuff i have encountered. Per the Hornady 9th edition reloading manual I'm using Federal 210 primers and Hornady 105gr match 243 bullets. Here's (one of) the issue(s).....according to the manual (Hornady 9th), one of the powders on the list is "H4350". I thought that meant "IMR 4350" so I bought it except all the "IMR" powders are actually designated "IMR xxxx" like "IMR 4831" (which is also on the list)....however "IMR 4350" is NOT on the list. So what the heck did I buy? and could this be why the gun shoots SEVEN INCH groups at 100yds?....I have never seen a gun shoot so terribly...and its not the gun....or me. Me and this gun have consecutively hit torso sized steel plate at 500yds in a 10mph crosswind with factory 100gr ammo. So should I just make exploding targets out of the stuff I got and start over with a powder thats actually on the list?

[Sure Shot Mc Gee]

At a time when I did shoot my 243. I shot high test full house loads under a medium weight bullet. (75-80 gr.) At that time my choice of powder was indeed IMR 4831 as it gave me my best accuracy and speed. As far as 4350 powders. I've enclosed a burn chart (Link) for your interpretation. There are differences between the major brands concerning their labeling per se (4350.)__ {See 113 & 114.} As you can read the two commented on are very close in burn time. Would one or the other make that much difference?__ I'll leave that question go to one of the more enlightened than I powder guru's to chime in about.
Oh by the way Welcome to the TFLF Site 105gr.___S/S

http://www.imrpowder.com/burn-rate.html

[105gr]

Thats why I posted the issue here. Thank you very much

[Bart B.]

http://www.6mmbr.com/243Win.html

The above's a good place to start. There is a small difference between IMR and H powders with the same numbers. Maybe a grain difference as indicated in the better loading data sites. The IMR ones are more consistant across lots is the only real difference, in my opinion.

Take the supressor off and retest for accuracy. More than a few so equipped rifles have their bullets scraping the supressor's insides a very tiny bit; enough cause the accuracy issue you have.

[Cowboy_mo]

There is one detail missing from your post. What powder charge were you using that provided the "7 inch" spread?

If you shot several different charges (wts. of powder) it is easy to understand why they wouldn't group.

That said, different charge weights of the SAME powder, same bullet, same primer will shoot to different points of impact in the same gun.

Good luck in your search to find the load you are looking for.

P.S. I can tell you that IMR 4831 shoots very accurately through my .243 with several different charge weights and 100 grain hornady bullets.

Welcome to TFL.

[.45 Vet]

IMR4350 and H4350 are close but not identical across the board for reloading. I switched to H4350 in my 06 mainly because the powder granules metered better in my uni flow. I do have a M77 Target in .243 with a 26" bbl. and am having great results with IMR 3031 and H380. I am using 80gr HPs though.

I know several guys that load 105gr soft points for deer with IMR4350 and have had very good results. The rifles typically have 22/24" tubes.

I'm just curious if the factory ammo you were using was a plain base style compared to the match,(I assume boat-tail), bullet. I'm wondering the affect that a short tube, and maybe incomplete ignition of a slower powder combined with the up-set in gas pressure from the can would have on a boat-tailed bullet.

I guess I'm better at asking questions than answering them, sorry...

[FrankenMauser]

I know it may not be much help, and may even add some confusion, but....

I have tested H4350, IMR4350, and AA4350. H4350 is no longer welcome in my reloading room. The other two 4350s are much more consistent.
I use IMR4350 in some .30-06 loads, and AA4350 in 7.62x54R, .243 Win, and {something I'm forgetting }.

However, unlike IMR4350 and H4350, where you can use the other's load data as a baseline for a starting load (with a slight reduction), AA4350 data doesn't translate well to the other 4350s.

I don't think just substituting H4350 data for IMR4350 would cause the accuracy issues you're mentioning, unless you jumped straight to a maximum load. There's something else going on.


And, just a note: Keep in mind that most of the guys recommending slower burn rate powders are using longer barrels (including me, at 25"). With your stubby little tube, the 4350 burn rate class (or even a little faster) is more likely to give the best performance.

[243winxb]

The barrels rate of twist is to slow for that long bullet. Not enough rpm's with the short barrel.

[105gr]

Thank you all for the replies. Yes, i left some details out so I'll try to explain that part. I started the first batch of 5 at 37gr of powder but with a much longer cartridge length. I had been reading that guys were taking the bullets out to within .010" of the lands so I made a dummy round to see where they were. I can fit a cartridge thats 2.817" in the gun cold. First 5 rounds measured 2.800" and by the time I got to the 4th round they wouldnt chamber(I assumed because of heat). Second set of 5 seated at 2.710" which is the max length in the manual and the same thing happened with 36gr of powder. The first batch shot better....second shot worse...now I have 5 loaded at 2.700" with the load turned back up to 37gr. And as far as the twist rate not being fast enough, it specifically says the 105gr A-Max will not stabilize in a 1:10 or slower twist barrel but nothing about the match, and if it DID include the match, I'm still faster than 1:10 AND it shoots 100gr factory loads just fine.

[105gr]

and i also have to add that I dont have a chrony yet so I really have no clue where I am on the chart...

[105gr]

*UPDATE*...i got to thinkin about factory rounds firing just fine so I set the OAL at 2.650" which is alot closer to factory rounds and it shot alot better....then I turned up the heat from 37gr to 38gr and it got better yet...i went all the way to 39.5 in 1/2gr incriments but so far 38gr has yielded the best results

[FrankenMauser]

And as far as the twist rate not being fast enough, it specifically says the 105gr A-Max will not stabilize in a 1:10 or slower twist barrel but nothing about the match, and if it DID include the match, I'm still faster than 1:10 AND it shoots 100gr factory loads just fine.

Twist rate and velocity are co-dependent for bullet stabilization, especially in marginal applications.

If you don't have enough velocity, even a 1:8" or 1:9" twist rate won't stabilize that 105 gr bullet.

Using a more standard OAL (2.700" to 2.760"), work that load back up from 37 gr to 41 gr of IMR 4350, with a standard LR primer. I would suggest 0.3 gr or 0.5 gr increments. If you run into pressure signs, stop. Otherwise, keep increasing the load (up to 41 gr), to see if you reach a point where the groups start shrinking.

It also wouldn't hurt to take a close look at that suppressor, to make sure it isn't causing problems and hasn't been damaged.


Velocity/twist, in general -
As velocity increases, twist rate can decrease.
And as velocity decreases, twist rate can (or must) increase.

[105gr]

Well you confirmed my theory about the MV not being fast enough to get the bullet rpm's fast enough to stabilize the 105gr. Today I went from 38gr up to 39.5gr and didnt really see an improvement once I got away from 38gr. I was going to go back down to like 37.8 and see what it does but now that you mention it I guess I could take it up some more. At 39.5gr I didnt see any signs of over pressure so I guess I still have headroom.....I REALLY need a chrony....