1. 24 straight fluted, BCA side charging, 1:8 twist, Stainless heavy barrel. Worked up a sub MOA load and have 1200 yard milk jug impacts. 123gr SST, 28.2gr 8208xbr, Fed205GMM primer, 2.250 OAL. 2551fps.
2. New build, 12 rounds fired down the tube. Alexander Arms 18 stainless lite fluted, 1:7.5 twist, mid-length gas. Cleaned the barrel and built the upper (Anderson upper, Anderson lower, Larue MBT 2 stage trigger). Shot my above mentioned handloads and the first two groups were 1.5 & 2.75 five shot groups respectively. Shot off of a bench using sand bags and 1min between shots.
My question is: will bullet seating depth make my current recipe work for the new 18 barrel, or will I end up needing to completely rework the load from scratch?
Thanks in advance and glad to be here on the forum!
I would reply to your question by comparing factory ammo. If it is excellent quality ammo, the chances are good that it will work well in a wide variety of guns, but some guns will love it and some will hate it. I hope your new gun is not a hater.
Your current load is hot. Your actual case volume will be slightly different to Quickload's default but it is showing 105% case full at 28.2gn/8208 and 2.250" OAL with that bullet. The pressure is up around 63.4K lbs. It is more than the light action is designed for and while you may be OK it may break the bolt - sooner or later. Hard to say when it will break and also depends on the quality of your parts.
8208 is unforgiving once it gets compressed and 105% is definitely compressed. The pressure curve gets steep real quick.
I don't think 8208 is suitable for the heavier bullets and also not the most efficient for that long barrel. You'd be better off with 4895 - no more than 27gn if you want peace of mind. If you don't mind the idea of replacing parts if they break then you can experiment with hotter.
New gun, different barrel length, different chamber dimensions = new work-up.
Welcome to the forum Banjo! I dont think you can make a blanket statement on accuracy on a new build, especially with one hand load. Further testing might reveal your gas block is hitting the hand guard under recoil and affecting accuracy or some other anomaly. It could be the AA barrel just doesnt shoot the 123 grain SST bullet well.
It is not uncommon to have manufacturing difference to where seating the bullet at 2.260 C.O.A.L. is in the lands of one barrel and off the lands by a couple thousandths in another barrel.
Your current load is hot. Your actual case volume will be slightly different to Quickload's default but it is showing 105% case full at 28.2gn/8208 and 2.250" OAL with that bullet. The pressure is up around 63.4K lbs. It is more than the light action is designed for and while you may be OK it may break the bolt - sooner or later. Hard to say when it will break and also depends on the quality of your parts.
8208 is unforgiving once it gets compressed and 105% is definitely compressed. The pressure curve gets steep real quick.
How are you determining your muzzle velocity?
Thanks for the informed reply, I havent used quickload. I went off of the load chart from hodgdon reloadings website. Starting load of 25.5, max load of 28.5. Worked up from 26.0 iirc and never saw any pressure signs with 8208 all the way up to the max load. I did see pressure with AR-comp and primers were starting to back out. All loads chronographed with my RCBS ammomaster chrono. At 28.2gn I can still hear powder shaking around in the case, although I dont know if thats a scientific way to check.
At any rate, I appreciate the reply and will report back with what works out to be an accurate load for this barrel.
VASCAR2 Wrote:Welcome to the forum Banjo! I dont think you can make a blanket statement on accuracy on a new build, especially with one hand load. Further testing might reveal your gas block is hitting the hand guard under recoil and affecting accuracy or some other anomaly. It could be the AA barrel just doesnt shoot the 123 grain SST bullet well.
It is not uncommon to have manufacturing difference to where seating the bullet at 2.260 C.O.A.L. is in the lands of one barrel and off the lands by a couple thousandths in another barrel.
I had to cut the handguard down short of the gas block because it actually WAS hitting inside the large ID tube handguard. I cut it down before I took it to the range for the first time. I may have to breakdown and get a (seating depth) OAL gauge so I can check this chamber out. Cant be wasting powder or primers in the current climate. Thanks for the warm welcome!
Welcome to the forum from another New Mexican. I'm in Albuquerque & do all my shootin' at the Zia R & P club. From the pic of your 24" Grendel, it looks like you might be in northern New Mexico. This site is an education... learned a lot here.
I refuse to be victimized by notions of virtuous behavior.
Welcome to the clan, B, from your neighbor on the east. Not all over-pressure symptoms become evident prior to critical failure, It isn't worth it - start from scratch. You did well with the long stick, no reason you won't have good luck with the shorter one. But, start slowly.
Something is not right. 28.2/8208 is 105% full and you can shake it around like there's an air pocket? At 103% full is where I start to feel crunching when you seat the bullet. At 105%
Your velocity is also low for the load.
Are you quite comfortable all that info in your earlier post is accurate?
Entering 2551fps into JBM ballistics has a 123SST going subsonic at 1100yards. Having shot F Class for many years I can tell you no-one will be shooting a target as small as a milk jug at 1200 with any confidence. Transonic (1,350fps) is where groups start to blow out and is reached at 800yds with your load. From 800 to 1200 yds is a lot of range for a group to get bigger and bigger and bigger as it goes wobbly. How many rounds did it take to hit that jug? Did any go through on an angle (elongated holes)? Are you at a high altitude?
Something is not right. 28.2/8208 is 105% full and you can shake it around like there's an air pocket? At 103% full is where I start to feel crunching when you seat the bullet. At 105%
Your velocity is also low for the load.
Are you quite comfortable all that info in your earlier post is accurate?
Entering 2551fps into JBM ballistics has a 123SST going subsonic at 1100yards. Having shot F Class for many years I can tell you no-one will be shooting a target as small as a milk jug at 1200 with any confidence. Transonic (1,350fps) is where groups start to blow out and is reached at 800yds with your load. From 800 to 1200 yds is a lot of range for a group to get bigger and bigger and bigger as it goes wobbly. How many rounds did it take to hit that jug? Did any go through on an angle (elongated holes)? Are you at a high altitude?
Yes sir, Im at 6900 and shoot at the High Power range in Capitan, NM. I give myself 10 shots per jug and loosely follow the LRSU rules for shooting jugs at 1000yds plus. Link to a shorter video below. The bullet impacts at a downward descending angle on the jug, but isnt key holing the entry hole.
Old Bob Wrote:Welcome to the forum from another New Mexican. I'm in Albuquerque & do all my shootin' at the Zia R & P club. From the pic of your 24" Grendel, it looks like you might be in northern New Mexico. This site is an education... learned a lot here.
Im down in Ruidoso. Hunt hogs in west Texas and thats where one of those pictures is from. Thanks for the warm welcome.
Banjo Wrote:Yes sir, Im at 6900 and shoot at the High Power range in Capitan, NM. I give myself 10 shots per jug and loosely follow the LRSU rules for shooting jugs at 1000yds plus. Link to a shorter video below. The bullet impacts at a downward descending angle on the jug, but isnt key holing the entry hole.
That is fantastic shooting, well done. Love the video. So, half a mil low is 50cm I think. Then you go high 50cm Were you offsetting (adjusting for the previous shot) or keeping the same POA and expecting it to hit at some stage in the group?
6,900ft makes a huge difference to ballistics. It goes subsonic at 1,400yds. The transonic blow-out starts a lot closer to the target so the group is proportionally smaller than at sea level. Also realised that a US milk jug is 3.75litres - our standard milk jug is 2 litres.
Thanks Klem. I was surprised when I walked it in on the first jug I hit. Then the second jug impact was a little easier given I already had the dope. I was keeping the same POA and expecting it to find the target. I figured the variance in elevation of impact was due to my breathing timing. The jugs I was shooting are approximately 6 wide x 9.5 tall. Hoping this new barrel makes tiny groups and puts down lots of hogs.
