.223 80-95gr, T/C Encore Twist Rate

[iplaywithnoshoes]

I'm interested in a .223 build using an Encore Action and MGM barrel. This setup is intended for 80 and 90gr. I've seen a few threads here where shooters are getting good results with SMKs, VLDs, and Hornady ELD-Ms in that range and would like to try something similar.

Some specs in mind:

20 MOA Steel Base
1" Straight Stainless Bull Barrel
27" (Maximum Length Available)
1-7 and 1-6 twists available
Chamber can be given as much free bore and throating as needed based on a dummy round.

I want to know:

1. What twist rate do you recommend or use and for what reason?
2. Where do I start with charge weights and OAL or at least, what do you personally use and why? If not COAL, how much jump or jam?
3. How much freebore do you guys typically spec in your chambers for 90s and beyond?

I'm looking to push between 2800-2850ft/s at the high end for the 90s but I understand that this is up to the barrel.

Any advice is appreciated.

shoe

 

[stacy]

1/7 with .169 free bore is what works for me I shoot 80 gr vld’s and 90 gr vld’s very well

 

[Ned Ludd]

No need to go faster than a 7.0-twist at that barrel length and expected velocity. In fact, there is a clear association between twist rates faster than 7.0 and bullet jacket failures with the 90 VLDs and 88 ELDMs. Another alternative that may allow the use of twist rates faster than 7.0 is to go with a 0.219"/0.224" bore/groove configuration, rather than 0.218"/0.224".

With regard to chambering, PTGs .223 Rem ISSF reamer that cuts 0.169" freebore is a good place to start with the 90 SMKs and 90 VLDs. However, the ISSF freebore is not nearly long enough to seat the Hornady 88 ELDM optimally; something in the 0.250" freebore range would be much better. The ISSF reamer freebore will also work with the 80.5 Fullbore and other typical 80 gr bullets of similar BTO dimensions. Obviously, the 80s will be seated a bit farther out the neck than the 90s in a rifle chambered with the ISSF reamer in order to maintain some specific distance from the lands. I wouldn't attempt to shoot typical 80 gr bullets out of a rifle chambered with a freebore optimal for the 88 ELDM, it'd be too long.

 

[iplaywithnoshoes]

1/7 with .169 free bore is what works for me I shoot 80 gr vld’s and 90 gr vld’s very well

Any particular powders that worked well?

 

[iplaywithnoshoes]

No need to go faster than a 7.0-twist at that barrel length and expected velocity. In fact, there is a clear association between twist rates faster than 7.0 and bullet jacket failures with the 90 VLDs and 88 ELDMs. Another alternative that may allow the use of twist rates faster than 7.0 is to go with a 0.219"/0.224" bore/groove configuration, rather than 0.218"/0.224".

With regard to chambering, PTGs .223 Rem ISSF reamer that cuts 0.169" freebore is a good place to start with the 90 SMKs and 90 VLDs. However, the ISSF freebore is not nearly long enough to seat the Hornady 88 ELDM optimally; something in the 0.250" freebore range would be much better. The ISSF reamer freebore will also work with the 80.5 Fullbore and other typical 80 gr bullets of similar BTO dimensions. Obviously, the 80s will be seated a bit farther out the neck than the 90s in a rifle chambered with the ISSF reamer in order to maintain some specific distance from the lands. I wouldn't attempt to shoot typical 80 gr bullets out of a rifle chambered with a freebore optimal for the 88 ELDM, it'd be too long.

So in this case, a 169" throat would limit me to the 88-90gr range for a few manufacturers since there is little support at the case neck and throat right? MGM uses a simple throat reamer which could potentially get me to that .169" range if I specify it to them.

 

[Ned Ludd]

So in this case, a 169" throat would limit me to the 88-90gr range for a few manufacturers since there is little support at the case neck and throat right? MGM uses a simple throat reamer which could potentially get me to that .169" range if I specify it to them.

In general that is correct, although I'm not sure what you mean about there being little support at the case neck and throat. Within the heaviest class of .224" bullets, the 88 ELDM and the Sierra 95 Matchking require significantly longer freebore than 0.169" for optimal seating. 90 VLDs, 90 SMKs, 80.5s, etc., should work reasonably well with the 0.169" fb. You can get away with using less, but that will require more pressure at a given velocity and brass life with heavies in the .223 Rem can be poor if they're pushed hard. Ifd you plan to shoot a bullets of both 80 gr and 90 gr, I'd load up dummy rounds with both and send those in. Hopefully, they could then bracket the optimum freebore for you.

 

[stacy]

Any particular powders that worked well?

YEP RL-15 WITH THE 80GRS AND VARGET WITH THE 90GRS 450M PRIMERS TO START THE FIRE