2 years ago worked up a load that shoots very well for my TRG-42 with Lapua Brass, using 92.5gr of H1000 and 300gr SMKs. When I was working it up I didn't notice the bolt operating hard at all. However recently when I've shot it the bolt will lift very easy untill it comes to the final part of the cam where the bolt cocks. It is very hard and doesn't move easily. I don't notice any extractor marsk on the brass and the primers look normal. I don't want to re develop the load but will if I'm on the warm side. Is this the case from your previous experiences? Any suggestions will be greatly appreciated.
oTRG-42, 300gr SMKs, H1000, Lapua Brass a question
- Thread starter Heman
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Re: oTRG-42, 300gr SMKs, H1000, Lapua Brass a question
Could you quantify "very difficult"? Sounds to me like you don't have classic over-pressure difficult bolt lift issues. Sounds to me like something is causing your cocking functionality to stick or be difficult...?
If you were over pressure, I would expect the entire bolt lift to be difficult, because the case is "pinched" between the shoulder in the chamber and the bolt face. If that is in fact the situation, any rotation of the bolt is made difficult, because the bolt face and ejector are rubbing the casehead.
You didn't mention how your primers look? Do they still have a radius on their edge? Temperature differences between load development and as of late?
Could you quantify "very difficult"? Sounds to me like you don't have classic over-pressure difficult bolt lift issues. Sounds to me like something is causing your cocking functionality to stick or be difficult...?
If you were over pressure, I would expect the entire bolt lift to be difficult, because the case is "pinched" between the shoulder in the chamber and the bolt face. If that is in fact the situation, any rotation of the bolt is made difficult, because the bolt face and ejector are rubbing the casehead.
You didn't mention how your primers look? Do they still have a radius on their edge? Temperature differences between load development and as of late?
Re: oTRG-42, 300gr SMKs, H1000, Lapua Brass a question
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Heman</div><div class="ubbcode-body">2 years ago worked up a load that shoots very well for my TRG-42 with Lapua Brass, using 92.5gr of H1000 and 300gr SMKs. When I was working it up I didn't notice the bolt operating hard at all. However recently when I've shot it the bolt will lift very easy untill it comes to the final part of the cam where the bolt cocks. It is very hard and doesn't move easily. I don't notice any extractor marsk on the brass and the primers look normal. I don't want to re develop the load but will if I'm on the warm side. Is this the case from your previous experiences? Any suggestions will be greatly appreciated. </div></div>
I run a TRGs action in 338LM and get the same thing with 91 - 92 gr of H1000 with 300 gr SMK's. I'm pretty sure our actions are the same. It's hard to describe; the bolt lifts easily until the last part if the lift and then it is tight. I wouldn't call it 'very hard' in mine, but tight/stiff. I usually just kind of bump it with my palm when I open it. Like you, I haven't had any ejector marks, blown primers, cratered primers, or any other signs of over pressure. I would consider the primers to be slightly flattened, but not overly flattened. I also get it with other loads, not just that one. I have to really load down to make the lift go away. Have you tried re-shooting the load with virgin brass? I have suspected for some time that this was the reason that it didn't do it for me when I first worked up the load, but I haven't ponied up for a new lot of brass to try my theory. Also I'm on the same lot of powder that I started out with.
Having played with the bolt a lot, if you open the bolt without a round in it and with it already cocked, you can feel the bolt lift in two phases... one straight up to the point where it is normally hard to lift, then it goes loose briefly, then the final part of the lift, which in this case is about equal in pressure/resistance to the first part of the lift. This second phase of the lift is about where the action at the stem of the bolt takes a ~ 45 degree angle back towards the stock and where the bolt first begins to move rearward. I have always suspected that the bolt lift is a quirk of this particular action, but have no way to prove my suspicion.
FWIW, I know that in my rifle at least, that 92 gr of H1000 is on the warm side. I can tell that it works the brass pretty well, in that I have to bump the shoulder every time I load or I have trouble chambering the round and I have to trim the necks more frequently with this load to keep them in spec.
That said, it is an awsome load and I have fired 494 rounds of it without incident. Both ES and SD are single digit and it consistently groups under 1/2 moa.
I'm watching this thread with great interest, hoping for some informative and experienced replies.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Heman</div><div class="ubbcode-body">2 years ago worked up a load that shoots very well for my TRG-42 with Lapua Brass, using 92.5gr of H1000 and 300gr SMKs. When I was working it up I didn't notice the bolt operating hard at all. However recently when I've shot it the bolt will lift very easy untill it comes to the final part of the cam where the bolt cocks. It is very hard and doesn't move easily. I don't notice any extractor marsk on the brass and the primers look normal. I don't want to re develop the load but will if I'm on the warm side. Is this the case from your previous experiences? Any suggestions will be greatly appreciated. </div></div>
I run a TRGs action in 338LM and get the same thing with 91 - 92 gr of H1000 with 300 gr SMK's. I'm pretty sure our actions are the same. It's hard to describe; the bolt lifts easily until the last part if the lift and then it is tight. I wouldn't call it 'very hard' in mine, but tight/stiff. I usually just kind of bump it with my palm when I open it. Like you, I haven't had any ejector marks, blown primers, cratered primers, or any other signs of over pressure. I would consider the primers to be slightly flattened, but not overly flattened. I also get it with other loads, not just that one. I have to really load down to make the lift go away. Have you tried re-shooting the load with virgin brass? I have suspected for some time that this was the reason that it didn't do it for me when I first worked up the load, but I haven't ponied up for a new lot of brass to try my theory. Also I'm on the same lot of powder that I started out with.
Having played with the bolt a lot, if you open the bolt without a round in it and with it already cocked, you can feel the bolt lift in two phases... one straight up to the point where it is normally hard to lift, then it goes loose briefly, then the final part of the lift, which in this case is about equal in pressure/resistance to the first part of the lift. This second phase of the lift is about where the action at the stem of the bolt takes a ~ 45 degree angle back towards the stock and where the bolt first begins to move rearward. I have always suspected that the bolt lift is a quirk of this particular action, but have no way to prove my suspicion.
FWIW, I know that in my rifle at least, that 92 gr of H1000 is on the warm side. I can tell that it works the brass pretty well, in that I have to bump the shoulder every time I load or I have trouble chambering the round and I have to trim the necks more frequently with this load to keep them in spec.
That said, it is an awsome load and I have fired 494 rounds of it without incident. Both ES and SD are single digit and it consistently groups under 1/2 moa.
I'm watching this thread with great interest, hoping for some informative and experienced replies.
Re: oTRG-42, 300gr SMKs, H1000, Lapua Brass a question
How you described your primers is exactly how mine look they still have a radius on them, and yes I did use Virgin brass when I worked the load up. And hitting it with my hand does the trick also.
When I proofed the load I did it at a 3x600 fun match and they allowed me to shoot with my muzzle break 200-14X clean and there was little to no vertical deviation so if it's just a quirk of the action that is fine with me as this load really shoots.
How you described your primers is exactly how mine look they still have a radius on them, and yes I did use Virgin brass when I worked the load up. And hitting it with my hand does the trick also.
When I proofed the load I did it at a 3x600 fun match and they allowed me to shoot with my muzzle break 200-14X clean and there was little to no vertical deviation so if it's just a quirk of the action that is fine with me as this load really shoots.
