[EWP]

How much H322 can I put behind a 110gr bullet (Hornady hollow point & Nosler Accubond) using a DPMS 16" M4 with a SAAMI 1/10 twist 6 groove barrel before the pressure is to high using new Hornady brass, and also need a recommendation on which primer to use(I have CCI400, #41, & Rem 7 1/2, 2K of each)?

 

[ArtFWTx]

I'll let the others give you some load recipes. I'm posting the SPC II conversion post in case you wanted to look into converting your chamber to SPC II like many have done. It will definitely give you more room to work with pressure wise.

http://68forums.com/forums/showthread.php?t=5614

 

[EWP]

I do plan to do this, I put my self on the list for the reamer today but may send it to ADCO and have it done.

 

[rcrandall]

Hodgdon's load data has been up for several years and was made for saami chambers. It lists a 110 grain vmax in Remington cases with Remington 9.5 primers with 29 grains of H322 as a max load. I would start at 28 grains with that barrel and work up, checking for ejector swipes and flat primers.

 

[EWP]

Didn't know if the Hodgdon data was for SMMAI or not.

I also have H335, Benchmark, & Varget, are any of these more popular than H322 for 6.8 loads?

I have one more Q that may be dumb but what causes H322 to give more velocity out of the 6.8 cartridge than H335 when in .223 H335 produces more velocity than H322? I just don't quite understand why one powder can be faster in one case and not the other, I would have thought if H335 produces more velocity at 25 gr's in .223 than H322 it would still produce more velocity at 29 gr's in the 6.8. Can anyone explain why this is, if you understand my question.

 

[rcrandall]

Varget is too slow, the others will work okay. H322 is one of the best powders for the 6.8 because of it's burn rate, temperture insensitivity, and it seems to get good velocity and accuracy. The reason one powder outperforming another in a cartridge has to do with burn rate and any other number of things that I don't know enough about to put down in writting, or talk about in any intelligent way. I think Tim W or Constructor (or a any number of other guys here) can describe it better.

 

[EWP]

That's another thing that stumps me with the 6.8 cartridge, most that have more case volume and heavier bullets require a slower burning powder yet the 6.8 likes a faster burning powder.

Its not a big deal just a little confusing vs what I have learned since starting to reload.

 

[grimini]

How much H322 can I put behind a 110gr bullet (Hornady hollow point & Nosler Accubond) using a DPMS 16" M4 with a SAAMI 1/10 twist 6 groove barrel before the pressure is to high using new Hornady brass, and also need a recommendation on which primer to use(I have CCI400, #41, & Rem 7 1/2, 2K of each)?

I too, have this barrel and my best load is the 110 Pro-hunter, 28.5 Grains H335, 2.270", Remington brass and primers.

This is my deer hunting load and it's inside an inch at 100 yards.

I struggled long and hard with several bullets and powders, possibly not long enough but this was the best I could come up with.

I tried the Accu-bonds and the Barnes TSX and neither were as good as the PH so I just stuck with them and tuned my OAL till it shot.

I don't know how fast it is... but it shoots well and my freezer is full of deer meat.

I'm hesitant to ream out my chamber in fear of reducing my accuracy, I've spent alot of money to get this thing to shoot well even though it may not be optimum fast.

 

[EWP]

I know what you mean, I'm going to do allot of playing with mine and see how good I can do before I start reaming out a chamber that might be good enough. DPMS usually has good shooting guns, so I'll see about this one before changing anything just yet.

 

[nemohunter]

That's another thing that stumps me with the 6.8 cartridge, most that have more case volume and heavier bullets require a slower burning powder yet the 6.8 likes a faster burning powder.

Its not a big deal just a little confusing vs what I have learned since starting to reload.

the powder speed a cartridge likes has to do with multiple things. bullet wieght is the first and most drastic of these. then comes case capacity. then bore to case ratio. then shoulder angle/diameter. when you start to increase any of these things the powder speed drops. if you AI'ed a 6.8 you could easoly run the same powders that we run in the 5.56. i dont know how reliable it would be.

 

[dlance13]

If you are using Hornady bullets and CCI41 primers, just go straight out of the Hornady manual. They used the DPMS SAAMI 1:10 for their testing.

 

[EWP]

I wounder just how much the pressure would drop from Hornady's loads with regular primers because #41 primers just aren't needed with H322. I do know they produce a good bit more pressure, I had some .223 loads using Varget that I used 41's with instead of the 400's I'd been using and it flattened the primers like pancakes, were the same load with the 400 primers was below max and just fine.

 

[dlance13]

Like with any reloading (especially when your components differ from those in the manuals) you need to work up a load from mid to low end depending on which end of the spectrum your differences are (ex: hotter primer, start lower end; milder primer, start midrange).

Chuck Hawks has a great writeup on primers. Here is a snippet regarding pressures and primers:

From http://www.chuckhawks.com/primers.htm

Primers affect the pressure generated by the cartridge. Changing from standard to magnum primers may substantially raise the maximum average pressure of the cartridge and indiscriminate changes are not recommended. The A-Square Company conducted pressure tests involving six different primers. These tests used the 7mm Remington Magnum cartridge with a 160 grain Sierra BT bullet and 66.0 grains of H4831 powder and the results were reported in the A-Square reloading manual Any Shot You Want. A-Square used CCI 200 and 250, Federal 215, Remington 9 1/2M, and Winchester WLRM and WLR primers in these tests. They revealed a total spread in pressure of 12,800 psi from the mildest standard (the CCI 200) to the hottest magnum (WLRM) primer tested.

Changing brands but using the same type of primer will also usually result in pressure changes, but ordinarily these will be less drastic. In the A-Square tests the pressure spread between the CCI 200 and the hottest standard primer (the WLR) was 9600 psi. The spread between the mildest magnum primer (the Rem. 9 1/2M) and the hottest magnum primer (WLRM) was 8300 psi. These are significant pressure variations that cannot safely be disregarded.

Incidentally, these same tests revealed that the Federal 215 and CCI 250 large rifle magnum primers produced nearly identical pressures. The difference between these two primers was only 100 psi. A-Square also reported that, while they had not tested these two primers in all possible cartridges, this result was typical of their experience with these two primers.