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Discussion Starter #1
Afternoon y'all, I am fairly new to the Swiss rifle club but have been enjoying it maybe a bit too much. I picked up a Schmidt Rubin 1911 with some West German Anschutz target sights on it a couple months back and am now a familiar face at my local range. Now with the current GP-11(or any ammo for that matter) situation I am starting to consider getting into hand loading when primers start showing up again. I've read across a couple of forums about people being worried about shooting GP-11 out of a 1911 and swearing they'd only shoot it out of a K-31 and use a lighter load for their 1911. The reasoning behind this is that the 1911's locking lugs are located in the middle of the bolt (supposedly weaker) compared to the k-31 (front lugs). Does anyone know of any comparisons in bolt strength/ideal pressure dependent on lug position? Even just personal experience would be appreciated. In an ideal world I'd love to recreate the performance of GP-11 in my rifle or at the very least be able to shoot a moderate power round without worrying about the longevity of my gun too much.
 

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The K11 was designed to shoot GP11. If you remove the bolt from both a K31 and K11, you may observe that the locking lugs of the K11's bolt sleeve are dimensionally larger than the K31's. In other words, more steel keeps the K11 bolt closed than the K31's.
 

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The Swiss certainly shot millions of rounds of GP11 thru 96/11s, 1911 rifles and carbines over the last 100 plus years. I think any strength limitations would be very obvious to us all by now.
 

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Discussion Starter #4
Sirs, thank y'all very much for the input. I had a notion in my mind that some of the talk of no GP11 in G11s was being a tad overly cautious but as a research oriented individual I wanted some more data. Going forward when I do end up designing or adapting a hand load I will feel safe using the GP-11's pressure as a target or upper limit.
 

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Nothing to do with Swiss rifles, but you asked for examples. The Mark III British service rifle is a prime example of lug placement causing problems. The Savage model 99 is a rear locking lever rifle. When rifles have a locking area towards the rear of the rifle, the receiver tends to "Spring" under a heavy load. This means the receiver actually stretches and then returns to the original position when cleared. I actually experienced this with a 99 Savage in .243. I had bought three different brands of ammo to set up the scope. The Federal and Winchester were hot and all over the target. The lever was really sticky on extraction and the brass stretched out quite a bit. The Remington were smooth extraction and you could cover the group with a quarter. Apparently the receiver went back to original size, as head space gauges were fine in it. Keep in mind that this was factory ammunition.
 

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It is not a coincidence that the rifle is a G11 and the ammunition is GP11. They were DESIGNED to work together.

No problems using GP11 at all.
 

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Discussion Starter #7
The general conclusion I'm gathering is that Gp-11 level pressures are completely safe, higher pressure doesn't mean a better round and there will need to be a good deal of experimentation, and safety should be the number one goal as always.
 

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Nothing to do with Swiss rifles, but you asked for examples. The Mark III British service rifle is a prime example of lug placement causing problems. The Savage model 99 is a rear locking lever rifle. When rifles have a locking area towards the rear of the rifle, the receiver tends to "Spring" under a heavy load. This means the receiver actually stretches and then returns to the original position when cleared. I actually experienced this with a 99 Savage in .243. I had bought three different brands of ammo to set up the scope. The Federal and Winchester were hot and all over the target. The lever was really sticky on extraction and the brass stretched out quite a bit. The Remington were smooth extraction and you could cover the group with a quarter. Apparently the receiver went back to original size, as head space gauges were fine in it. Keep in mind that this was factory ammunition.
The K31 can also suffer "stretching" or, more accurately, lug set back. There is a difference between receiver stretching, which is transient, as "Deerhound" described, and set back, which is permanent. BTW there are specific numbered bolt heads for the Enfield No 4 intended to close up excess head space resulting from set back.

Similarly, there are "orthotic" bolt heads for the K31. If you remove the extractor from the bolt head, you may find a small stamped number 5 or 10. These are for correcting headspace growth resulting from lug set back.

A number of years ago Graf's was selling small parts for the K31 including the #5 and #10 bolt heads. A friend was having problems with excessive case stretching with his 7.5x55 reloads. I suggested he get the "orthotic" bolt heads - they were not at all expensive - and try them. He did and solved his problem.
 
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