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Posted: 11/16/2021 12:17:27 PM EDT
As mentioned in my other thread my new GA Precision rifle arrived and I picked it up yesterday. The first bullet I am going to test in it is the 139 Scenar. Using the coal tool per my standard routine I discovered this chamber is different. When I push the bullet forward I hit resistance and that’s where I stopped. The measurement was really short and the bullet was very deep in the case. So I grabbed another bullet and tried again. This time when I hit the resistance I pushed a little harder and it slid in to a solid stop on the lands. I did this with 10 more rounds and came up with very consistent measurements at 2.2491 ogive length giving an approximate 2.75 oal.
The question is do I load to this length or load to the short length and give it “freebore?” FWIW, I’ve been hand loading for 25 years and this is the first time I have encountered this. Thanks for your input. 
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CA, USA
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Posted: 11/16/2021 12:48:28 PM EDT
[Last Edit: ballisticxlr]
[#1]
I always start my precision rifle match loads at .010 off the lands with anything from .22-.30cal and am usually rewarded with not having to fuck around with jump tuning. YMMV. Don't jam. That only ever leads to trouble. Benchrest guys and some few others do it but jamming into the lands makes unloading without firing a great way to spill powder in your action and chamber.
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Posted: 11/16/2021 1:28:16 PM EDT
[Last Edit: SpeyRod]
[#2]
Quote HistoryOriginally Posted By ballisticxlr: I always start my precision rifle match loads at .010 off the lands with anything from .22-.30cal and am usually rewarded with not having to fuck around with jump tuning. YMMV. Don't jam. That only ever leads to trouble. Benchrest guys and some few others do it but jamming into the lands makes unloading without firing a great way to spill powder in your action and chamber. I normally start all my load work ups at .01 off the lands. To achieve that I need to seat into the friction fit of the throat. It may be that it will listen up as I break the rifle in. I’m just in unknown territory with this tight throat. |
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CA, USA
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Posted: 11/16/2021 1:59:50 PM EDT
[#3]
It'll definitely loosen up as you shoot it. That what throat erosion is doing, ablating material from the throat. IIRC hornady makes a tool with a specially threaded case that makes finding the right jump distance a lot easier.
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Posted: 11/16/2021 2:22:06 PM EDT
[#4]
Quote HistoryOriginally Posted By ballisticxlr: It'll definitely loosen up as you shoot it. That what throat erosion is doing, ablating material from the throat. IIRC hornady makes a tool with a specially threaded case that makes finding the right jump distance a lot easier. That’s the tool I use for all my work ups. |
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Posted: 11/16/2021 5:20:40 PM EDT
[#5]
What chamber they use for it for freebore?
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Posted: 11/16/2021 5:51:04 PM EDT
[#6]
Quote HistoryOriginally Posted By Rob01: What chamber they use for it for freebore? I didn’t ask that. I can give them a call to try and find out. |
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Posted: 11/16/2021 6:20:34 PM EDT
[#7]
Quote HistoryOriginally Posted By SpeyRod: I didn’t ask that. I can give them a call to try and find out. Might want to as that is pretty short. The SAAMI chamber for the Creedmoor is .199 freebore. With a 140 ELD I am at 2.870" touching the lands. You shouldn't be down at 2.750" with a 139 Scenar unless it's a non SAAMI chamber. |
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Posted: 11/16/2021 6:48:37 PM EDT
[#8]
Quote HistoryOriginally Posted By Rob01: Might want to as that is pretty short. The SAAMI chamber for the Creedmoor is .199 freebore. With a 140 ELD I am at 2.870" touching the lands. You shouldn't be down at 2.750" with a 139 Scenar unless it's a non SAAMI chamber. Understood. I am going to measure the point where the throat touches the bullet and compare that to the land measurements. That should give me a freebore length. For now, I am going to do my normal load work up starting.01 off the lands. If the pressure starts spiking early I’ll know I need to reconsider my procedures. |
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Posted: 11/17/2021 5:02:13 PM EDT
[#9]
Quote HistoryOriginally Posted By Rob01: Might want to as that is pretty short. The SAAMI chamber for the Creedmoor is .199 freebore. With a 140 ELD I am at 2.870" touching the lands. You shouldn't be down at 2.750" with a 139 Scenar unless it's a non SAAMI chamber. Spoke with GAP and they said the chamber was cut to minimum SAAMI dimensions. They tested the throat with a 140 eldm and it was fine. Could be my technique with the coal tool. I am going to do my normal load work up and watch for pressure signs. |
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Posted: 11/17/2021 5:15:42 PM EDT
[#10]
Quote HistoryOriginally Posted By SpeyRod: Spoke with GAP and they said the chamber was cut to minimum SAAMI dimensions. They tested the throat with a 140 eldm and it was fine. Could be my technique with the coal tool. I am going to do my normal load work up and watch for pressure signs. Could be. I would try and load to 2.800" oal with a dummy round and see if it chambers. |
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Posted: 11/18/2021 1:07:13 AM EDT
[#11]
Quote HistoryOriginally Posted By Rob01: Could be. I would try and load to 2.800" oal with a dummy round and see if it chambers. I’ll give it a try. I hate not knowing or worse, not doing something properly. |
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Posted: 11/18/2021 6:16:13 AM EDT
[#12]
Quote HistoryOriginally Posted By SpeyRod: I’ll give it a try. I hate not knowing or worse, not doing something properly. Meh, if its short, take it to a competent smith and have them throat it for the bullets you want to shoot at the OAL you need... 
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Posted: 11/18/2021 10:02:58 AM EDT
[#13]
Quote HistoryOriginally Posted By AKSnowRider: Meh, if its short, take it to a competent smith and have them throat it for the bullets you want to shoot at the OAL you need... That's what I would do too. I wouldn't live with it being short. I am sure GAP would do it for you and if you had the tools you could ship just the barrel back. |
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Posted: 11/18/2021 9:55:58 PM EDT
[#14]
Well the good news is after talking with GA Precision I loaded work up loads for the 140 eldm and for the 139 Scenar. The great news is that when seated .01” off the lands the 140 is precisely 2.80” coal the 139 is 2.795” coal. This must not be their first rodeo….
Plan is to sight in with factory 143 eldx while following their break in routine. Then I will switch to my handloads and never look back! |
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Posted: 11/18/2021 10:27:07 PM EDT
[#15]
Quote HistoryOriginally Posted By SpeyRod: Well the good news is after talking with GA Precision I loaded work up loads for the 140 eldm and for the 139 Scenar. The great news is that when seated .01” off the lands the 140 is precisely 2.80” coal the 139 is 2.795” coal. This must not be their first rodeo…. Plan is to sight in with factory 143 eldx while following their break in routine. Then I will switch to my handloads and never look back! That’s fine but far off SAAMI. Will be close if shooting factory ammo but should be ok. |
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Posted: 11/21/2021 3:11:19 AM EDT
[Last Edit: SpeyRod]
[#16]
I am more than a little happy with the results today. I followed GAP’s break in procedure precisely. Shot one and clean. Repeat until the barrel shows minimal copper. That took 10 rounds and 3 1/2 hours. Then I shot the workup load with the 140 eldm. Started at 39.1 gr H4350 and stepped up .2 gr to 40.9 gr. First five rounds of the eldm’s:
 Attached FileI cleaned the barrel, adjusted up .2 and left .2 and shot the last 5 rounds.  Attached FileI think this will work… 
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Posted: 11/21/2021 10:55:50 AM EDT
[#17]
Could have saved you 3.5 hours if you asked but done now. LOL Yup looks like it will work great for you. Load them up and go have fun. What was the velocity?
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Posted: 11/21/2021 11:38:55 AM EDT
[#18]
Quote HistoryOriginally Posted By Rob01: Could have saved you 3.5 hours if you asked but done now. LOL Yup looks like it will work great for you. Load them up and go have fun. What was the velocity? The 139 Scenar’s hit 2,654 at 40.9. The eldm’s were tracking with the Scenar’s but I forgot to plug the crony back in for the last 5.  I am going out again today and will get that data.
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Posted: 11/21/2021 11:49:45 AM EDT
[#19]
Quote HistoryOriginally Posted By SpeyRod: The 139 Scenar’s hit 2,654 at 40.9. The eldm’s were tracking with the Scenar’s but I forgot to plug the crony back in for the last 5. I am going out again today and will get that data.Sounds good. Not bad for a 22". Any pressure at the 40.9 of H4350? If not you can try and work up if you wanted. |
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Posted: 11/21/2021 3:54:11 PM EDT
[Last Edit: SpeyRod]
[#20]
Quote HistoryOriginally Posted By Rob01: Sounds good. Not bad for a 22". Any pressure at the 40.9 of H4350? If not you can try and work up if you wanted. Five rounds 40.9 H4350 2,680 sd 6.8. The group is the upper right and I threw one high. Just starting to see a little shine on the base, primers are good and interesting enough the cases look new other than minimal powder at the neck. Not getting any powder from the should back. The 40.5 gr load was the most accurate and was running 2,657 with an sd of 13.8 and a .5” group. What I am finding is I need to work on my position and patience. I threw three shots which throws my data points off.  Attached File |
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Posted: 11/23/2021 12:21:03 PM EDT
[#21]
I start Sierra Match Kings .020 " to .025" off the lands. Sierra bullets jump just fine. You might want to try the 123 and 130 grain bullets. They are very accurate and can achieve high velocities.
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Posted: 11/23/2021 12:56:53 PM EDT
[#22]
Quote HistoryOriginally Posted By borderpatrol: I start Sierra Match Kings .020 " to .025" off the lands. Sierra bullets jump just fine. You might want to try the 123 and 130 grain bullets. They are very accurate and can achieve high velocities. Thanks for reminding me! I do have some 130 Berger’s that shot lights out from my LaRue. I think I’ll load some and see what they do. |
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